+ {{ if .ShowPrev }}
+ {{ t "Previous" }}
+ {{ else }}
+ {{ t "Previous" }}
+ {{ end }}
+
+
+
+ {{ if .ShowNext }}
+ {{ t "Next" }}
+ {{ else }}
+ {{ t "Next" }}
+ {{ end }}
+
+
+{{ end }}
+`,
+}
+
+var templateCommonMapChecksums = map[string]string{
+ "entry_pagination": "f1465fa70f585ae8043b200ec9de5bf437ffbb0c19fb7aefc015c3555614ee27",
+ "layout": "8be69cc93fdc99eb36841ae645f58488bd675670507dcdb2de0e593602893178",
+ "pagination": "6ff462c2b2a53bc5448b651da017f40a39f1d4f16cef4b2f09784f0797286924",
+}
diff --git a/server/template/helper/LICENSE b/server/template/helper/LICENSE
new file mode 100644
index 00000000..036a2a16
--- /dev/null
+++ b/server/template/helper/LICENSE
@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2017 Hervé GOUCHET
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/server/template/helper/elapsed.go b/server/template/helper/elapsed.go
new file mode 100644
index 00000000..bc312062
--- /dev/null
+++ b/server/template/helper/elapsed.go
@@ -0,0 +1,61 @@
+// Copyright (c) 2017 Hervé Gouchet. All rights reserved.
+// Use of this source code is governed by the MIT License
+// that can be found in the LICENSE file.
+
+package helper
+
+import (
+ "github.com/miniflux/miniflux2/locale"
+ "math"
+ "time"
+)
+
+// Texts to be translated if necessary.
+var (
+ NotYet = `not yet`
+ JustNow = `just now`
+ LastMinute = `1 minute ago`
+ Minutes = `%d minutes ago`
+ LastHour = `1 hour ago`
+ Hours = `%d hours ago`
+ Yesterday = `yesterday`
+ Days = `%d days ago`
+ Weeks = `%d weeks ago`
+ Months = `%d months ago`
+ Years = `%d years ago`
+)
+
+// GetElapsedTime returns in a human readable format the elapsed time
+// since the given datetime.
+func GetElapsedTime(translator *locale.Language, t time.Time) string {
+ if t.IsZero() || time.Now().Before(t) {
+ return translator.Get(NotYet)
+ }
+ diff := time.Since(t)
+ // Duration in seconds
+ s := diff.Seconds()
+ // Duration in days
+ d := int(s / 86400)
+ switch {
+ case s < 60:
+ return translator.Get(JustNow)
+ case s < 120:
+ return translator.Get(LastMinute)
+ case s < 3600:
+ return translator.Get(Minutes, int(diff.Minutes()))
+ case s < 7200:
+ return translator.Get(LastHour)
+ case s < 86400:
+ return translator.Get(Hours, int(diff.Hours()))
+ case d == 1:
+ return translator.Get(Yesterday)
+ case d < 7:
+ return translator.Get(Days, d)
+ case d < 31:
+ return translator.Get(Weeks, int(math.Ceil(float64(d)/7)))
+ case d < 365:
+ return translator.Get(Months, int(math.Ceil(float64(d)/30)))
+ default:
+ return translator.Get(Years, int(math.Ceil(float64(d)/365)))
+ }
+}
diff --git a/server/template/helper/elapsed_test.go b/server/template/helper/elapsed_test.go
new file mode 100644
index 00000000..67b8d6b7
--- /dev/null
+++ b/server/template/helper/elapsed_test.go
@@ -0,0 +1,37 @@
+// Copyright (c) 2017 Hervé Gouchet. All rights reserved.
+// Use of this source code is governed by the MIT License
+// that can be found in the LICENSE file.
+
+package helper
+
+import (
+ "fmt"
+ "github.com/miniflux/miniflux2/locale"
+ "testing"
+ "time"
+)
+
+func TestElapsedTime(t *testing.T) {
+ var dt = []struct {
+ in time.Time
+ out string
+ }{
+ {time.Time{}, NotYet},
+ {time.Now().Add(time.Hour), NotYet},
+ {time.Now(), JustNow},
+ {time.Now().Add(-time.Minute), LastMinute},
+ {time.Now().Add(-time.Minute * 40), fmt.Sprintf(Minutes, 40)},
+ {time.Now().Add(-time.Hour), LastHour},
+ {time.Now().Add(-time.Hour * 3), fmt.Sprintf(Hours, 3)},
+ {time.Now().Add(-time.Hour * 32), Yesterday},
+ {time.Now().Add(-time.Hour * 24 * 3), fmt.Sprintf(Days, 3)},
+ {time.Now().Add(-time.Hour * 24 * 14), fmt.Sprintf(Weeks, 2)},
+ {time.Now().Add(-time.Hour * 24 * 60), fmt.Sprintf(Months, 2)},
+ {time.Now().Add(-time.Hour * 24 * 365 * 3), fmt.Sprintf(Years, 3)},
+ }
+ for i, tt := range dt {
+ if out := GetElapsedTime(&locale.Language{}, tt.in); out != tt.out {
+ t.Errorf("%d. content mismatch for %v:exp=%q got=%q", i, tt.in, tt.out, out)
+ }
+ }
+}
diff --git a/server/template/html/about.html b/server/template/html/about.html
new file mode 100644
index 00000000..3596327f
--- /dev/null
+++ b/server/template/html/about.html
@@ -0,0 +1,37 @@
+{{ define "title"}}{{ t "About" }}{{ end }}
+
+{{ define "content"}}
+
+
+{{ else }}
+ {{ if ne .feed.ParsingErrorCount 0 }}
+
+
{{ t "Last Parsing Error" }}
+ {{ .feed.ParsingErrorMsg }}
+
+ {{ end }}
+
+
+{{ end }}
+
+{{ end }}
\ No newline at end of file
diff --git a/server/template/html/edit_user.html b/server/template/html/edit_user.html
new file mode 100644
index 00000000..8f63307d
--- /dev/null
+++ b/server/template/html/edit_user.html
@@ -0,0 +1,44 @@
+{{ define "title"}}{{ t "Edit user: %s" .selected_user.Username }}{{ end }}
+
+{{ define "content"}}
+
+
"
+ q.SetText(repl)
+
+ assertLength(t, doc.Find("#replace").Nodes, 0)
+ assertLength(t, doc.Find("#main, #foot").Nodes, 2)
+
+ if q.Text() != (repl + repl) {
+ t.Errorf("Expected text to be %v, found %v", (repl + repl), q.Text())
+ }
+
+ h, err := q.Html()
+ if err != nil {
+ t.Errorf("Error: %v", err)
+ }
+ esc := "<div id="replace">test</div>"
+ if h != esc {
+ t.Errorf("Expected html to be %v, found %v", esc, h)
+ }
+
+ printSel(t, doc.Selection)
+}
+
+func TestReplaceWithSelection(t *testing.T) {
+ doc := Doc2Clone()
+ sel := doc.Find("#nf6").ReplaceWithSelection(doc.Find("#nf5"))
+
+ assertSelectionIs(t, sel, "#nf6")
+ assertLength(t, doc.Find("#nf6").Nodes, 0)
+ assertLength(t, doc.Find("#nf5").Nodes, 1)
+
+ printSel(t, doc.Selection)
+}
+
+func TestUnwrap(t *testing.T) {
+ doc := Doc2Clone()
+
+ doc.Find("#nf5").Unwrap()
+ assertLength(t, doc.Find("#foot").Nodes, 0)
+ assertLength(t, doc.Find("body > #nf1").Nodes, 1)
+ assertLength(t, doc.Find("body > #nf5").Nodes, 1)
+
+ printSel(t, doc.Selection)
+
+ doc = Doc2Clone()
+
+ doc.Find("#nf5, #n1").Unwrap()
+ assertLength(t, doc.Find("#foot").Nodes, 0)
+ assertLength(t, doc.Find("#main").Nodes, 0)
+ assertLength(t, doc.Find("body > #n1").Nodes, 1)
+ assertLength(t, doc.Find("body > #nf5").Nodes, 1)
+
+ printSel(t, doc.Selection)
+}
+
+func TestUnwrapBody(t *testing.T) {
+ doc := Doc2Clone()
+
+ doc.Find("#main").Unwrap()
+ assertLength(t, doc.Find("body").Nodes, 1)
+ assertLength(t, doc.Find("body > #main").Nodes, 1)
+
+ printSel(t, doc.Selection)
+}
+
+func TestUnwrapHead(t *testing.T) {
+ doc := Doc2Clone()
+
+ doc.Find("title").Unwrap()
+ assertLength(t, doc.Find("head").Nodes, 0)
+ assertLength(t, doc.Find("head > title").Nodes, 0)
+ assertLength(t, doc.Find("title").Nodes, 1)
+
+ printSel(t, doc.Selection)
+}
+
+func TestUnwrapHtml(t *testing.T) {
+ doc := Doc2Clone()
+
+ doc.Find("head").Unwrap()
+ assertLength(t, doc.Find("html").Nodes, 0)
+ assertLength(t, doc.Find("html head").Nodes, 0)
+ assertLength(t, doc.Find("head").Nodes, 1)
+
+ printSel(t, doc.Selection)
+}
+
+func TestWrap(t *testing.T) {
+ doc := Doc2Clone()
+ doc.Find("#nf1").Wrap("#nf2")
+ nf1 := doc.Find("#foot #nf2 #nf1")
+ assertLength(t, nf1.Nodes, 1)
+
+ nf2 := doc.Find("#nf2")
+ assertLength(t, nf2.Nodes, 2)
+
+ printSel(t, doc.Selection)
+}
+
+func TestWrapEmpty(t *testing.T) {
+ doc := Doc2Clone()
+ doc.Find("#nf1").Wrap("#doesnt-exist")
+
+ origHtml, _ := Doc2().Html()
+ newHtml, _ := doc.Html()
+
+ if origHtml != newHtml {
+ t.Error("Expected the two documents to be identical.")
+ }
+
+ printSel(t, doc.Selection)
+}
+
+func TestWrapHtml(t *testing.T) {
+ doc := Doc2Clone()
+ doc.Find(".odd").WrapHtml(wrapHtml)
+ nf2 := doc.Find("#ins #nf2")
+ assertLength(t, nf2.Nodes, 1)
+ printSel(t, doc.Selection)
+}
+
+func TestWrapSelection(t *testing.T) {
+ doc := Doc2Clone()
+ doc.Find("#nf1").WrapSelection(doc.Find("#nf2"))
+ nf1 := doc.Find("#foot #nf2 #nf1")
+ assertLength(t, nf1.Nodes, 1)
+
+ nf2 := doc.Find("#nf2")
+ assertLength(t, nf2.Nodes, 2)
+
+ printSel(t, doc.Selection)
+}
+
+func TestWrapAll(t *testing.T) {
+ doc := Doc2Clone()
+ doc.Find(".odd").WrapAll("#nf1")
+ nf1 := doc.Find("#main #nf1")
+ assertLength(t, nf1.Nodes, 1)
+
+ sel := nf1.Find("#n2 ~ #n4 ~ #n6 ~ #nf2 ~ #nf4 ~ #nf6")
+ assertLength(t, sel.Nodes, 1)
+
+ printSel(t, doc.Selection)
+}
+
+func TestWrapAllHtml(t *testing.T) {
+ doc := Doc2Clone()
+ doc.Find(".odd").WrapAllHtml(wrapHtml)
+ nf1 := doc.Find("#main div#ins div p em b #n2 ~ #n4 ~ #n6 ~ #nf2 ~ #nf4 ~ #nf6")
+ assertLength(t, nf1.Nodes, 1)
+ printSel(t, doc.Selection)
+}
+
+func TestWrapInnerNoContent(t *testing.T) {
+ doc := Doc2Clone()
+ doc.Find(".one").WrapInner(".two")
+
+ twos := doc.Find(".two")
+ assertLength(t, twos.Nodes, 4)
+ assertLength(t, doc.Find(".one .two").Nodes, 2)
+
+ printSel(t, doc.Selection)
+}
+
+func TestWrapInnerWithContent(t *testing.T) {
+ doc := Doc3Clone()
+ doc.Find(".one").WrapInner(".two")
+
+ twos := doc.Find(".two")
+ assertLength(t, twos.Nodes, 4)
+ assertLength(t, doc.Find(".one .two").Nodes, 2)
+
+ printSel(t, doc.Selection)
+}
+
+func TestWrapInnerNoWrapper(t *testing.T) {
+ doc := Doc2Clone()
+ doc.Find(".one").WrapInner(".not-exist")
+
+ twos := doc.Find(".two")
+ assertLength(t, twos.Nodes, 2)
+ assertLength(t, doc.Find(".one").Nodes, 2)
+ assertLength(t, doc.Find(".one .two").Nodes, 0)
+
+ printSel(t, doc.Selection)
+}
+
+func TestWrapInnerHtml(t *testing.T) {
+ doc := Doc2Clone()
+ doc.Find("#foot").WrapInnerHtml(wrapHtml)
+
+ foot := doc.Find("#foot div#ins div p em b #nf1 ~ #nf2 ~ #nf3")
+ assertLength(t, foot.Nodes, 1)
+
+ printSel(t, doc.Selection)
+}
diff --git a/vendor/github.com/PuerkitoBio/goquery/misc/git/pre-commit b/vendor/github.com/PuerkitoBio/goquery/misc/git/pre-commit
new file mode 100755
index 00000000..6a3d7984
--- /dev/null
+++ b/vendor/github.com/PuerkitoBio/goquery/misc/git/pre-commit
@@ -0,0 +1,52 @@
+#!/bin/sh
+
+echo ">>> golint"
+for dir in $(go list ./... | grep -v /vendor/)
+do
+ golint "${dir}"
+done
+echo "<<< golint"
+echo
+
+echo ">>> go vet"
+go vet $(go list ./... | grep -v /vendor/)
+echo "<<< go vet"
+echo
+
+echo ">>> gosimple"
+gosimple $(go list ./... | grep -v /vendor/)
+echo "<<< gosimple"
+echo
+
+echo ">>> staticcheck"
+staticcheck $(go list ./... | grep -v /vendor/)
+echo "<<< staticcheck"
+echo
+
+echo ">>> unused"
+unused $(go list ./... | grep -v /vendor/)
+echo "<<< unused"
+echo
+
+echo ">>> gas"
+gas $(find . -name "*.go" | grep -v /vendor/ | grep -v '_test.go$')
+echo "<<< gas"
+echo
+
+# Check for gofmt problems and report if any.
+gofiles=$(git diff --cached --name-only --diff-filter=ACM | grep '.go$' | grep -v /vendor/)
+[ -z "$gofiles" ] && echo "EXIT $vetres" && exit $vetres
+
+if [ -n "$gofiles" ]; then
+ unformatted=$(gofmt -l $gofiles)
+
+ if [ -n "$unformatted" ]; then
+ # Some files are not gofmt'd.
+ echo >&2 "Go files must be formatted with gofmt. Please run:"
+ for fn in $unformatted; do
+ echo >&2 " gofmt -w $PWD/$fn"
+ done
+ fi
+fi
+echo
+
diff --git a/vendor/github.com/PuerkitoBio/goquery/property.go b/vendor/github.com/PuerkitoBio/goquery/property.go
new file mode 100644
index 00000000..411126db
--- /dev/null
+++ b/vendor/github.com/PuerkitoBio/goquery/property.go
@@ -0,0 +1,275 @@
+package goquery
+
+import (
+ "bytes"
+ "regexp"
+ "strings"
+
+ "golang.org/x/net/html"
+)
+
+var rxClassTrim = regexp.MustCompile("[\t\r\n]")
+
+// Attr gets the specified attribute's value for the first element in the
+// Selection. To get the value for each element individually, use a looping
+// construct such as Each or Map method.
+func (s *Selection) Attr(attrName string) (val string, exists bool) {
+ if len(s.Nodes) == 0 {
+ return
+ }
+ return getAttributeValue(attrName, s.Nodes[0])
+}
+
+// AttrOr works like Attr but returns default value if attribute is not present.
+func (s *Selection) AttrOr(attrName, defaultValue string) string {
+ if len(s.Nodes) == 0 {
+ return defaultValue
+ }
+
+ val, exists := getAttributeValue(attrName, s.Nodes[0])
+ if !exists {
+ return defaultValue
+ }
+
+ return val
+}
+
+// RemoveAttr removes the named attribute from each element in the set of matched elements.
+func (s *Selection) RemoveAttr(attrName string) *Selection {
+ for _, n := range s.Nodes {
+ removeAttr(n, attrName)
+ }
+
+ return s
+}
+
+// SetAttr sets the given attribute on each element in the set of matched elements.
+func (s *Selection) SetAttr(attrName, val string) *Selection {
+ for _, n := range s.Nodes {
+ attr := getAttributePtr(attrName, n)
+ if attr == nil {
+ n.Attr = append(n.Attr, html.Attribute{Key: attrName, Val: val})
+ } else {
+ attr.Val = val
+ }
+ }
+
+ return s
+}
+
+// Text gets the combined text contents of each element in the set of matched
+// elements, including their descendants.
+func (s *Selection) Text() string {
+ var buf bytes.Buffer
+
+ // Slightly optimized vs calling Each: no single selection object created
+ var f func(*html.Node)
+ f = func(n *html.Node) {
+ if n.Type == html.TextNode {
+ // Keep newlines and spaces, like jQuery
+ buf.WriteString(n.Data)
+ }
+ if n.FirstChild != nil {
+ for c := n.FirstChild; c != nil; c = c.NextSibling {
+ f(c)
+ }
+ }
+ }
+ for _, n := range s.Nodes {
+ f(n)
+ }
+
+ return buf.String()
+}
+
+// Size is an alias for Length.
+func (s *Selection) Size() int {
+ return s.Length()
+}
+
+// Length returns the number of elements in the Selection object.
+func (s *Selection) Length() int {
+ return len(s.Nodes)
+}
+
+// Html gets the HTML contents of the first element in the set of matched
+// elements. It includes text and comment nodes.
+func (s *Selection) Html() (ret string, e error) {
+ // Since there is no .innerHtml, the HTML content must be re-created from
+ // the nodes using html.Render.
+ var buf bytes.Buffer
+
+ if len(s.Nodes) > 0 {
+ for c := s.Nodes[0].FirstChild; c != nil; c = c.NextSibling {
+ e = html.Render(&buf, c)
+ if e != nil {
+ return
+ }
+ }
+ ret = buf.String()
+ }
+
+ return
+}
+
+// AddClass adds the given class(es) to each element in the set of matched elements.
+// Multiple class names can be specified, separated by a space or via multiple arguments.
+func (s *Selection) AddClass(class ...string) *Selection {
+ classStr := strings.TrimSpace(strings.Join(class, " "))
+
+ if classStr == "" {
+ return s
+ }
+
+ tcls := getClassesSlice(classStr)
+ for _, n := range s.Nodes {
+ curClasses, attr := getClassesAndAttr(n, true)
+ for _, newClass := range tcls {
+ if !strings.Contains(curClasses, " "+newClass+" ") {
+ curClasses += newClass + " "
+ }
+ }
+
+ setClasses(n, attr, curClasses)
+ }
+
+ return s
+}
+
+// HasClass determines whether any of the matched elements are assigned the
+// given class.
+func (s *Selection) HasClass(class string) bool {
+ class = " " + class + " "
+ for _, n := range s.Nodes {
+ classes, _ := getClassesAndAttr(n, false)
+ if strings.Contains(classes, class) {
+ return true
+ }
+ }
+ return false
+}
+
+// RemoveClass removes the given class(es) from each element in the set of matched elements.
+// Multiple class names can be specified, separated by a space or via multiple arguments.
+// If no class name is provided, all classes are removed.
+func (s *Selection) RemoveClass(class ...string) *Selection {
+ var rclasses []string
+
+ classStr := strings.TrimSpace(strings.Join(class, " "))
+ remove := classStr == ""
+
+ if !remove {
+ rclasses = getClassesSlice(classStr)
+ }
+
+ for _, n := range s.Nodes {
+ if remove {
+ removeAttr(n, "class")
+ } else {
+ classes, attr := getClassesAndAttr(n, true)
+ for _, rcl := range rclasses {
+ classes = strings.Replace(classes, " "+rcl+" ", " ", -1)
+ }
+
+ setClasses(n, attr, classes)
+ }
+ }
+
+ return s
+}
+
+// ToggleClass adds or removes the given class(es) for each element in the set of matched elements.
+// Multiple class names can be specified, separated by a space or via multiple arguments.
+func (s *Selection) ToggleClass(class ...string) *Selection {
+ classStr := strings.TrimSpace(strings.Join(class, " "))
+
+ if classStr == "" {
+ return s
+ }
+
+ tcls := getClassesSlice(classStr)
+
+ for _, n := range s.Nodes {
+ classes, attr := getClassesAndAttr(n, true)
+ for _, tcl := range tcls {
+ if strings.Contains(classes, " "+tcl+" ") {
+ classes = strings.Replace(classes, " "+tcl+" ", " ", -1)
+ } else {
+ classes += tcl + " "
+ }
+ }
+
+ setClasses(n, attr, classes)
+ }
+
+ return s
+}
+
+func getAttributePtr(attrName string, n *html.Node) *html.Attribute {
+ if n == nil {
+ return nil
+ }
+
+ for i, a := range n.Attr {
+ if a.Key == attrName {
+ return &n.Attr[i]
+ }
+ }
+ return nil
+}
+
+// Private function to get the specified attribute's value from a node.
+func getAttributeValue(attrName string, n *html.Node) (val string, exists bool) {
+ if a := getAttributePtr(attrName, n); a != nil {
+ val = a.Val
+ exists = true
+ }
+ return
+}
+
+// Get and normalize the "class" attribute from the node.
+func getClassesAndAttr(n *html.Node, create bool) (classes string, attr *html.Attribute) {
+ // Applies only to element nodes
+ if n.Type == html.ElementNode {
+ attr = getAttributePtr("class", n)
+ if attr == nil && create {
+ n.Attr = append(n.Attr, html.Attribute{
+ Key: "class",
+ Val: "",
+ })
+ attr = &n.Attr[len(n.Attr)-1]
+ }
+ }
+
+ if attr == nil {
+ classes = " "
+ } else {
+ classes = rxClassTrim.ReplaceAllString(" "+attr.Val+" ", " ")
+ }
+
+ return
+}
+
+func getClassesSlice(classes string) []string {
+ return strings.Split(rxClassTrim.ReplaceAllString(" "+classes+" ", " "), " ")
+}
+
+func removeAttr(n *html.Node, attrName string) {
+ for i, a := range n.Attr {
+ if a.Key == attrName {
+ n.Attr[i], n.Attr[len(n.Attr)-1], n.Attr =
+ n.Attr[len(n.Attr)-1], html.Attribute{}, n.Attr[:len(n.Attr)-1]
+ return
+ }
+ }
+}
+
+func setClasses(n *html.Node, attr *html.Attribute, classes string) {
+ classes = strings.TrimSpace(classes)
+ if classes == "" {
+ removeAttr(n, "class")
+ return
+ }
+
+ attr.Val = classes
+}
diff --git a/vendor/github.com/PuerkitoBio/goquery/property_test.go b/vendor/github.com/PuerkitoBio/goquery/property_test.go
new file mode 100644
index 00000000..1095dcc8
--- /dev/null
+++ b/vendor/github.com/PuerkitoBio/goquery/property_test.go
@@ -0,0 +1,252 @@
+package goquery
+
+import (
+ "regexp"
+ "strings"
+ "testing"
+)
+
+func TestAttrExists(t *testing.T) {
+ if val, ok := Doc().Find("a").Attr("href"); !ok {
+ t.Error("Expected a value for the href attribute.")
+ } else {
+ t.Logf("Href of first anchor: %v.", val)
+ }
+}
+
+func TestAttrOr(t *testing.T) {
+ if val := Doc().Find("a").AttrOr("fake-attribute", "alternative"); val != "alternative" {
+ t.Error("Expected an alternative value for 'fake-attribute' attribute.")
+ } else {
+ t.Logf("Value returned for not existing attribute: %v.", val)
+ }
+ if val := Doc().Find("zz").AttrOr("fake-attribute", "alternative"); val != "alternative" {
+ t.Error("Expected an alternative value for 'fake-attribute' on an empty selection.")
+ } else {
+ t.Logf("Value returned for empty selection: %v.", val)
+ }
+}
+
+func TestAttrNotExist(t *testing.T) {
+ if val, ok := Doc().Find("div.row-fluid").Attr("href"); ok {
+ t.Errorf("Expected no value for the href attribute, got %v.", val)
+ }
+}
+
+func TestRemoveAttr(t *testing.T) {
+ sel := Doc2Clone().Find("div")
+
+ sel.RemoveAttr("id")
+
+ _, ok := sel.Attr("id")
+ if ok {
+ t.Error("Expected there to be no id attributes set")
+ }
+}
+
+func TestSetAttr(t *testing.T) {
+ sel := Doc2Clone().Find("#main")
+
+ sel.SetAttr("id", "not-main")
+
+ val, ok := sel.Attr("id")
+ if !ok {
+ t.Error("Expected an id attribute on main")
+ }
+
+ if val != "not-main" {
+ t.Errorf("Expected an attribute id to be not-main, got %s", val)
+ }
+}
+
+func TestSetAttr2(t *testing.T) {
+ sel := Doc2Clone().Find("#main")
+
+ sel.SetAttr("foo", "bar")
+
+ val, ok := sel.Attr("foo")
+ if !ok {
+ t.Error("Expected an 'foo' attribute on main")
+ }
+
+ if val != "bar" {
+ t.Errorf("Expected an attribute 'foo' to be 'bar', got '%s'", val)
+ }
+}
+
+func TestText(t *testing.T) {
+ txt := Doc().Find("h1").Text()
+ if strings.Trim(txt, " \n\r\t") != "Provok.in" {
+ t.Errorf("Expected text to be Provok.in, found %s.", txt)
+ }
+}
+
+func TestText2(t *testing.T) {
+ txt := Doc().Find(".hero-unit .container-fluid .row-fluid:nth-child(1)").Text()
+ if ok, e := regexp.MatchString(`^\s+Provok\.in\s+Prove your point.\s+$`, txt); !ok || e != nil {
+ t.Errorf("Expected text to be Provok.in Prove your point., found %s.", txt)
+ if e != nil {
+ t.Logf("Error: %s.", e.Error())
+ }
+ }
+}
+
+func TestText3(t *testing.T) {
+ txt := Doc().Find(".pvk-gutter").First().Text()
+ // There's an character in there...
+ if ok, e := regexp.MatchString(`^[\s\x{00A0}]+$`, txt); !ok || e != nil {
+ t.Errorf("Expected spaces, found <%v>.", txt)
+ if e != nil {
+ t.Logf("Error: %s.", e.Error())
+ }
+ }
+}
+
+func TestHtml(t *testing.T) {
+ txt, e := Doc().Find("h1").Html()
+ if e != nil {
+ t.Errorf("Error: %s.", e)
+ }
+
+ if ok, e := regexp.MatchString(`^\s*Provok\.in\s*$`, txt); !ok || e != nil {
+ t.Errorf("Unexpected HTML content, found %s.", txt)
+ if e != nil {
+ t.Logf("Error: %s.", e.Error())
+ }
+ }
+}
+
+func TestNbsp(t *testing.T) {
+ src := `
Some text
`
+ d, err := NewDocumentFromReader(strings.NewReader(src))
+ if err != nil {
+ t.Fatal(err)
+ }
+ txt := d.Find("p").Text()
+ ix := strings.Index(txt, "\u00a0")
+ if ix != 4 {
+ t.Errorf("Text: expected a non-breaking space at index 4, got %d", ix)
+ }
+
+ h, err := d.Find("p").Html()
+ if err != nil {
+ t.Fatal(err)
+ }
+ ix = strings.Index(h, "\u00a0")
+ if ix != 4 {
+ t.Errorf("Html: expected a non-breaking space at index 4, got %d", ix)
+ }
+}
+
+func TestAddClass(t *testing.T) {
+ sel := Doc2Clone().Find("#main")
+ sel.AddClass("main main main")
+
+ // Make sure that class was only added once
+ if a, ok := sel.Attr("class"); !ok || a != "main" {
+ t.Error("Expected #main to have class main")
+ }
+}
+
+func TestAddClassSimilar(t *testing.T) {
+ sel := Doc2Clone().Find("#nf5")
+ sel.AddClass("odd")
+
+ assertClass(t, sel, "odd")
+ assertClass(t, sel, "odder")
+ printSel(t, sel.Parent())
+}
+
+func TestAddEmptyClass(t *testing.T) {
+ sel := Doc2Clone().Find("#main")
+ sel.AddClass("")
+
+ // Make sure that class was only added once
+ if a, ok := sel.Attr("class"); ok {
+ t.Errorf("Expected #main to not to have a class, have: %s", a)
+ }
+}
+
+func TestAddClasses(t *testing.T) {
+ sel := Doc2Clone().Find("#main")
+ sel.AddClass("a b")
+
+ // Make sure that class was only added once
+ if !sel.HasClass("a") || !sel.HasClass("b") {
+ t.Errorf("#main does not have classes")
+ }
+}
+
+func TestHasClass(t *testing.T) {
+ sel := Doc().Find("div")
+ if !sel.HasClass("span12") {
+ t.Error("Expected at least one div to have class span12.")
+ }
+}
+
+func TestHasClassNone(t *testing.T) {
+ sel := Doc().Find("h2")
+ if sel.HasClass("toto") {
+ t.Error("Expected h1 to have no class.")
+ }
+}
+
+func TestHasClassNotFirst(t *testing.T) {
+ sel := Doc().Find(".alert")
+ if !sel.HasClass("alert-error") {
+ t.Error("Expected .alert to also have class .alert-error.")
+ }
+}
+
+func TestRemoveClass(t *testing.T) {
+ sel := Doc2Clone().Find("#nf1")
+ sel.RemoveClass("one row")
+
+ if !sel.HasClass("even") || sel.HasClass("one") || sel.HasClass("row") {
+ classes, _ := sel.Attr("class")
+ t.Error("Expected #nf1 to have class even, has ", classes)
+ }
+}
+
+func TestRemoveClassSimilar(t *testing.T) {
+ sel := Doc2Clone().Find("#nf5, #nf6")
+ assertLength(t, sel.Nodes, 2)
+
+ sel.RemoveClass("odd")
+ assertClass(t, sel.Eq(0), "odder")
+ printSel(t, sel)
+}
+
+func TestRemoveAllClasses(t *testing.T) {
+ sel := Doc2Clone().Find("#nf1")
+ sel.RemoveClass()
+
+ if a, ok := sel.Attr("class"); ok {
+ t.Error("All classes were not removed, has ", a)
+ }
+
+ sel = Doc2Clone().Find("#main")
+ sel.RemoveClass()
+ if a, ok := sel.Attr("class"); ok {
+ t.Error("All classes were not removed, has ", a)
+ }
+}
+
+func TestToggleClass(t *testing.T) {
+ sel := Doc2Clone().Find("#nf1")
+
+ sel.ToggleClass("one")
+ if sel.HasClass("one") {
+ t.Error("Expected #nf1 to not have class one")
+ }
+
+ sel.ToggleClass("one")
+ if !sel.HasClass("one") {
+ t.Error("Expected #nf1 to have class one")
+ }
+
+ sel.ToggleClass("one even row")
+ if a, ok := sel.Attr("class"); ok {
+ t.Errorf("Expected #nf1 to have no classes, have %q", a)
+ }
+}
diff --git a/vendor/github.com/PuerkitoBio/goquery/query.go b/vendor/github.com/PuerkitoBio/goquery/query.go
new file mode 100644
index 00000000..1a7f8732
--- /dev/null
+++ b/vendor/github.com/PuerkitoBio/goquery/query.go
@@ -0,0 +1,53 @@
+package goquery
+
+import "golang.org/x/net/html"
+
+// Is checks the current matched set of elements against a selector and
+// returns true if at least one of these elements matches.
+func (s *Selection) Is(selector string) bool {
+ if len(s.Nodes) > 0 {
+ return s.IsMatcher(compileMatcher(selector))
+ }
+
+ return false
+}
+
+// IsMatcher checks the current matched set of elements against a matcher and
+// returns true if at least one of these elements matches.
+func (s *Selection) IsMatcher(m Matcher) bool {
+ if len(s.Nodes) > 0 {
+ if len(s.Nodes) == 1 {
+ return m.Match(s.Nodes[0])
+ }
+ return len(m.Filter(s.Nodes)) > 0
+ }
+
+ return false
+}
+
+// IsFunction checks the current matched set of elements against a predicate and
+// returns true if at least one of these elements matches.
+func (s *Selection) IsFunction(f func(int, *Selection) bool) bool {
+ return s.FilterFunction(f).Length() > 0
+}
+
+// IsSelection checks the current matched set of elements against a Selection object
+// and returns true if at least one of these elements matches.
+func (s *Selection) IsSelection(sel *Selection) bool {
+ return s.FilterSelection(sel).Length() > 0
+}
+
+// IsNodes checks the current matched set of elements against the specified nodes
+// and returns true if at least one of these elements matches.
+func (s *Selection) IsNodes(nodes ...*html.Node) bool {
+ return s.FilterNodes(nodes...).Length() > 0
+}
+
+// Contains returns true if the specified Node is within,
+// at any depth, one of the nodes in the Selection object.
+// It is NOT inclusive, to behave like jQuery's implementation, and
+// unlike Javascript's .contains, so if the contained
+// node is itself in the selection, it returns false.
+func (s *Selection) Contains(n *html.Node) bool {
+ return sliceContains(s.Nodes, n)
+}
diff --git a/vendor/github.com/PuerkitoBio/goquery/query_test.go b/vendor/github.com/PuerkitoBio/goquery/query_test.go
new file mode 100644
index 00000000..54b2a2e0
--- /dev/null
+++ b/vendor/github.com/PuerkitoBio/goquery/query_test.go
@@ -0,0 +1,103 @@
+package goquery
+
+import (
+ "testing"
+)
+
+func TestIs(t *testing.T) {
+ sel := Doc().Find(".footer p:nth-child(1)")
+ if !sel.Is("p") {
+ t.Error("Expected .footer p:nth-child(1) to be p.")
+ }
+}
+
+func TestIsInvalid(t *testing.T) {
+ sel := Doc().Find(".footer p:nth-child(1)")
+ if sel.Is("") {
+ t.Error("Is should not succeed with invalid selector string")
+ }
+}
+
+func TestIsPositional(t *testing.T) {
+ sel := Doc().Find(".footer p:nth-child(2)")
+ if !sel.Is("p:nth-child(2)") {
+ t.Error("Expected .footer p:nth-child(2) to be p:nth-child(2).")
+ }
+}
+
+func TestIsPositionalNot(t *testing.T) {
+ sel := Doc().Find(".footer p:nth-child(1)")
+ if sel.Is("p:nth-child(2)") {
+ t.Error("Expected .footer p:nth-child(1) NOT to be p:nth-child(2).")
+ }
+}
+
+func TestIsFunction(t *testing.T) {
+ ok := Doc().Find("div").IsFunction(func(i int, s *Selection) bool {
+ return s.HasClass("container-fluid")
+ })
+
+ if !ok {
+ t.Error("Expected some div to have a container-fluid class.")
+ }
+}
+
+func TestIsFunctionRollback(t *testing.T) {
+ ok := Doc().Find("div").IsFunction(func(i int, s *Selection) bool {
+ return s.HasClass("container-fluid")
+ })
+
+ if !ok {
+ t.Error("Expected some div to have a container-fluid class.")
+ }
+}
+
+func TestIsSelection(t *testing.T) {
+ sel := Doc().Find("div")
+ sel2 := Doc().Find(".pvk-gutter")
+
+ if !sel.IsSelection(sel2) {
+ t.Error("Expected some div to have a pvk-gutter class.")
+ }
+}
+
+func TestIsSelectionNot(t *testing.T) {
+ sel := Doc().Find("div")
+ sel2 := Doc().Find("a")
+
+ if sel.IsSelection(sel2) {
+ t.Error("Expected some div NOT to be an anchor.")
+ }
+}
+
+func TestIsNodes(t *testing.T) {
+ sel := Doc().Find("div")
+ sel2 := Doc().Find(".footer")
+
+ if !sel.IsNodes(sel2.Nodes[0]) {
+ t.Error("Expected some div to have a footer class.")
+ }
+}
+
+func TestDocContains(t *testing.T) {
+ sel := Doc().Find("h1")
+ if !Doc().Contains(sel.Nodes[0]) {
+ t.Error("Expected document to contain H1 tag.")
+ }
+}
+
+func TestSelContains(t *testing.T) {
+ sel := Doc().Find(".row-fluid")
+ sel2 := Doc().Find("a[ng-click]")
+ if !sel.Contains(sel2.Nodes[0]) {
+ t.Error("Expected .row-fluid to contain a[ng-click] tag.")
+ }
+}
+
+func TestSelNotContains(t *testing.T) {
+ sel := Doc().Find("a.link")
+ sel2 := Doc().Find("span")
+ if sel.Contains(sel2.Nodes[0]) {
+ t.Error("Expected a.link to NOT contain span tag.")
+ }
+}
diff --git a/vendor/github.com/PuerkitoBio/goquery/testdata/gotesting.html b/vendor/github.com/PuerkitoBio/goquery/testdata/gotesting.html
new file mode 100644
index 00000000..ba5348fd
--- /dev/null
+++ b/vendor/github.com/PuerkitoBio/goquery/testdata/gotesting.html
@@ -0,0 +1,855 @@
+
+
+
+
+
+ testing - The Go Programming Language
+
+
+
+
+
+
+
+
+
+
+
+Package testing provides support for automated testing of Go packages.
+It is intended to be used in concert with the “go test” command, which automates
+execution of any function of the form
+
+
func TestXxx(*testing.T)
+
+
+where Xxx can be any alphanumeric string (but the first letter must not be in
+[a-z]) and serves to identify the test routine.
+These TestXxx routines should be declared within the package they are testing.
+
+
+Functions of the form
+
+
func BenchmarkXxx(*testing.B)
+
+
+are considered benchmarks, and are executed by the "go test" command when
+the -test.bench flag is provided.
+
+
+A sample benchmark function looks like this:
+
+
func BenchmarkHello(b *testing.B) {
+ for i := 0; i < b.N; i++ {
+ fmt.Sprintf("hello")
+ }
+}
+
+
+The benchmark package will vary b.N until the benchmark function lasts
+long enough to be timed reliably. The output
+
+
testing.BenchmarkHello 10000000 282 ns/op
+
+
+means that the loop ran 10000000 times at a speed of 282 ns per loop.
+
+
+If a benchmark needs some expensive setup before running, the timer
+may be stopped:
+
+
func BenchmarkBigLen(b *testing.B) {
+ b.StopTimer()
+ big := NewBig()
+ b.StartTimer()
+ for i := 0; i < b.N; i++ {
+ big.Len()
+ }
+}
+
+
+The package also runs and verifies example code. Example functions may
+include a concluding comment that begins with "Output:" and is compared with
+the standard output of the function when the tests are run, as in these
+examples of an example:
+
+Multiple example functions for a type/function/method may be provided by
+appending a distinct suffix to the name. The suffix must start with a
+lower-case letter.
+
+The entire test file is presented as the example when it contains a single
+example function, at least one other function, type, variable, or constant
+declaration, and no test or benchmark functions.
+
+StartTimer starts timing a test. This function is called automatically
+before a benchmark starts, but it can also used to resume timing after
+a call to StopTimer.
+
type BenchmarkResult struct {
+ N int // The number of iterations.
+ T time.Duration // The total time taken.
+ Bytes int64 // Bytes processed in one iteration.
+}
type T struct {
+ // contains filtered or unexported fields
+}
+
+T is a type passed to Test functions to manage test state and support formatted test logs.
+Logs are accumulated during execution and dumped to standard error when done.
+
The syntax of Go is broadly similar to that of C: blocks of code are surrounded with curly braces; common control flow structures include for, switch, and if. Unlike C, line-ending semicolons are optional, variable declarations are written differently and are usually optional, type conversions must be made explicit, and new go and select control keywords have been introduced to support concurrent programming. New built-in types include maps, Unicode strings, array slices, and channels for inter-thread communication.
+
Go is designed for exceptionally fast compiling times, even on modest hardware.[10] The language requires garbage collection. Certain concurrency-related structural conventions of Go (channels and alternative channel inputs) are borrowed from Tony Hoare'sCSP. Unlike previous concurrent programming languages such as occam or Limbo, Go does not provide any built-in notion of safe or verifiable concurrency.[11]
+
Of features found in C++ or Java, Go does not include type inheritance, generic programming, assertions, method overloading, or pointer arithmetic.[2] Of these, the Go authors express an openness to generic programming, explicitly argue against assertions and pointer arithmetic, while defending the choice to omit type inheritance as giving a more useful language, encouraging heavy use of interfaces instead.[2] Initially, the language did not include exception handling, but in March 2010 a mechanism known as panic/recover was implemented to handle exceptional errors while avoiding some of the problems the Go authors find with exceptions.[12][13]
Go allows a programmer to write functions that can operate on inputs of arbitrary type, provided that the type implements the functions defined by a given interface.
+
Unlike Java, the interfaces a type supports do not need to be specified at the point at which the type is defined, and Go interfaces do not participate in a type hierarchy. A Go interface is best described as a set of methods, each identified by a name and signature. A type is considered to implement an interface if all the required methods have been defined for that type. An interface can be declared to "embed" other interfaces, meaning the declared interface includes the methods defined in the other interfaces.[11]
+
Unlike Java, the in-memory representation of an object does not contain a pointer to a virtual method table. Instead a value of interface type is implemented as a pair of a pointer to the object, and a pointer to a dictionary containing implementations of the interface methods for that type.
These four definitions could have been placed in separate files, in different parts of the program. Notably, the programmer who defined the Sequence type did not need to declare that the type implemented HasLength, and the person who implemented the Len method for Sequence did not need to specify that this method was part of HasLength.
Visibility of structures, structure fields, variables, constants, methods, top-level types and functions outside their defining package is defined implicitly according to the capitalization of their identifier.[14]
Go provides goroutines, small lightweight threads; the name alludes to coroutines. Goroutines are created with the go statement from anonymous or named functions.
+
Goroutines are executed in parallel with other goroutines, including their caller. They do not necessarily run in separate threads, but a group of goroutines are multiplexed onto multiple threads — execution control is moved between them by blocking them when sending or receiving messages over channels.
6g/8g/5g (the compilers for AMD64, x86, and ARM respectively) with their supporting tools (collectively known as "gc") based on Ken's previous work on Plan 9's C toolchain.
+
gccgo, a GCC frontend written in C++,[15] and now officially supported as of version 4.6, albeit not part of the standard binary for gcc.[16]
+
+
Both compilers work on Unix-like systems, and a port to Microsoft Windows of the gc compiler and runtime have been integrated in the main distribution. Most of the standard libraries also work on Windows.
+
There is also an unmaintained "tiny" runtime environment that allows Go programs to run on bare hardware.[17]
Go's automatic semicolon insertion feature requires that opening braces not be placed on their own lines, and this is thus the preferred brace style; the examples shown comply with this style.[18]
Michele Simionato wrote in an article for artima.com:[20]
+
+
Here I just wanted to point out the design choices about interfaces and inheritance. Such ideas are not new and it is a shame that no popular language has followed such particular route in the design space. I hope Go will become popular; if not, I hope such ideas will finally enter in a popular language, we are already 10 or 20 years too late :-(
Go is extremely easy to dive into. There are a minimal number of fundamental language concepts and the syntax is clean and designed to be clear and unambiguous. Go is still experimental and still a little rough around the edges.
+
+
Ars Technica interviewed Rob Pike, one of the authors of Go, and asked why a new language was needed. He replied that:[22]
+
+
It wasn't enough to just add features to existing programming languages, because sometimes you can get more in the long run by taking things away. They wanted to start from scratch and rethink everything. ... [But they did not want] to deviate too much from what developers already knew because they wanted to avoid alienating Go's target audience.
The complexity of C++ (even more complexity has been added in the new C++), and the resulting impact on productivity, is no longer justified. All the hoops that the C++ programmer had to jump through in order to use a C-compatible language make no sense anymore -- they're just a waste of time and effort. Now, Go makes much more sense for the class of problems that C++ was originally intended to solve.
On the day of the general release of the language, Francis McCabe, developer of the Go! programming language (note the exclamation point), requested a name change of Google's language to prevent confusion with his language.[25] The issue was closed by a Google developer on 12 October 2010 with the custom status "Unfortunate", with a comment that "there are many computing products and services named Go. In the 11 months since our release, there has been minimal confusion of the two languages."[26]
^"A Tutorial for the Go Programming Language". The Go Programming Language. Google. http://golang.org/doc/go_tutorial.html. Retrieved 10 March 2010. "In Go the rule about visibility of information is simple: if a name (of a top-level type, function, method, constant or variable, or of a structure field or method) is capitalized, users of the package may see it. Otherwise, the name and hence the thing being named is visible only inside the package in which it is declared."
^"A Tutorial for the Go Programming Language". The Go Programming Language. Google. http://golang.org/doc/go_tutorial.html. Retrieved 10 March 2010. "The one surprise is that it's important to put the opening brace of a construct such as an if statement on the same line as the if; however, if you don't, there are situations that may not compile or may give the wrong result. The language forces the brace style to some extent."
+
+
\ No newline at end of file
diff --git a/vendor/github.com/PuerkitoBio/goquery/testdata/page2.html b/vendor/github.com/PuerkitoBio/goquery/testdata/page2.html
new file mode 100644
index 00000000..4c2f92f4
--- /dev/null
+++ b/vendor/github.com/PuerkitoBio/goquery/testdata/page2.html
@@ -0,0 +1,24 @@
+
+
+
+ Tests for siblings
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/vendor/github.com/PuerkitoBio/goquery/testdata/page3.html b/vendor/github.com/PuerkitoBio/goquery/testdata/page3.html
new file mode 100644
index 00000000..17e86241
--- /dev/null
+++ b/vendor/github.com/PuerkitoBio/goquery/testdata/page3.html
@@ -0,0 +1,24 @@
+
+
+
+ Tests for siblings
+
+
+
+
hello
+
+
+
+
+
+
+
+
text
+
+
+
+
+
+
+
+
diff --git a/vendor/github.com/PuerkitoBio/goquery/traversal.go b/vendor/github.com/PuerkitoBio/goquery/traversal.go
new file mode 100644
index 00000000..5fa5315a
--- /dev/null
+++ b/vendor/github.com/PuerkitoBio/goquery/traversal.go
@@ -0,0 +1,698 @@
+package goquery
+
+import "golang.org/x/net/html"
+
+type siblingType int
+
+// Sibling type, used internally when iterating over children at the same
+// level (siblings) to specify which nodes are requested.
+const (
+ siblingPrevUntil siblingType = iota - 3
+ siblingPrevAll
+ siblingPrev
+ siblingAll
+ siblingNext
+ siblingNextAll
+ siblingNextUntil
+ siblingAllIncludingNonElements
+)
+
+// Find gets the descendants of each element in the current set of matched
+// elements, filtered by a selector. It returns a new Selection object
+// containing these matched elements.
+func (s *Selection) Find(selector string) *Selection {
+ return pushStack(s, findWithMatcher(s.Nodes, compileMatcher(selector)))
+}
+
+// FindMatcher gets the descendants of each element in the current set of matched
+// elements, filtered by the matcher. It returns a new Selection object
+// containing these matched elements.
+func (s *Selection) FindMatcher(m Matcher) *Selection {
+ return pushStack(s, findWithMatcher(s.Nodes, m))
+}
+
+// FindSelection gets the descendants of each element in the current
+// Selection, filtered by a Selection. It returns a new Selection object
+// containing these matched elements.
+func (s *Selection) FindSelection(sel *Selection) *Selection {
+ if sel == nil {
+ return pushStack(s, nil)
+ }
+ return s.FindNodes(sel.Nodes...)
+}
+
+// FindNodes gets the descendants of each element in the current
+// Selection, filtered by some nodes. It returns a new Selection object
+// containing these matched elements.
+func (s *Selection) FindNodes(nodes ...*html.Node) *Selection {
+ return pushStack(s, mapNodes(nodes, func(i int, n *html.Node) []*html.Node {
+ if sliceContains(s.Nodes, n) {
+ return []*html.Node{n}
+ }
+ return nil
+ }))
+}
+
+// Contents gets the children of each element in the Selection,
+// including text and comment nodes. It returns a new Selection object
+// containing these elements.
+func (s *Selection) Contents() *Selection {
+ return pushStack(s, getChildrenNodes(s.Nodes, siblingAllIncludingNonElements))
+}
+
+// ContentsFiltered gets the children of each element in the Selection,
+// filtered by the specified selector. It returns a new Selection
+// object containing these elements. Since selectors only act on Element nodes,
+// this function is an alias to ChildrenFiltered unless the selector is empty,
+// in which case it is an alias to Contents.
+func (s *Selection) ContentsFiltered(selector string) *Selection {
+ if selector != "" {
+ return s.ChildrenFiltered(selector)
+ }
+ return s.Contents()
+}
+
+// ContentsMatcher gets the children of each element in the Selection,
+// filtered by the specified matcher. It returns a new Selection
+// object containing these elements. Since matchers only act on Element nodes,
+// this function is an alias to ChildrenMatcher.
+func (s *Selection) ContentsMatcher(m Matcher) *Selection {
+ return s.ChildrenMatcher(m)
+}
+
+// Children gets the child elements of each element in the Selection.
+// It returns a new Selection object containing these elements.
+func (s *Selection) Children() *Selection {
+ return pushStack(s, getChildrenNodes(s.Nodes, siblingAll))
+}
+
+// ChildrenFiltered gets the child elements of each element in the Selection,
+// filtered by the specified selector. It returns a new
+// Selection object containing these elements.
+func (s *Selection) ChildrenFiltered(selector string) *Selection {
+ return filterAndPush(s, getChildrenNodes(s.Nodes, siblingAll), compileMatcher(selector))
+}
+
+// ChildrenMatcher gets the child elements of each element in the Selection,
+// filtered by the specified matcher. It returns a new
+// Selection object containing these elements.
+func (s *Selection) ChildrenMatcher(m Matcher) *Selection {
+ return filterAndPush(s, getChildrenNodes(s.Nodes, siblingAll), m)
+}
+
+// Parent gets the parent of each element in the Selection. It returns a
+// new Selection object containing the matched elements.
+func (s *Selection) Parent() *Selection {
+ return pushStack(s, getParentNodes(s.Nodes))
+}
+
+// ParentFiltered gets the parent of each element in the Selection filtered by a
+// selector. It returns a new Selection object containing the matched elements.
+func (s *Selection) ParentFiltered(selector string) *Selection {
+ return filterAndPush(s, getParentNodes(s.Nodes), compileMatcher(selector))
+}
+
+// ParentMatcher gets the parent of each element in the Selection filtered by a
+// matcher. It returns a new Selection object containing the matched elements.
+func (s *Selection) ParentMatcher(m Matcher) *Selection {
+ return filterAndPush(s, getParentNodes(s.Nodes), m)
+}
+
+// Closest gets the first element that matches the selector by testing the
+// element itself and traversing up through its ancestors in the DOM tree.
+func (s *Selection) Closest(selector string) *Selection {
+ cs := compileMatcher(selector)
+ return s.ClosestMatcher(cs)
+}
+
+// ClosestMatcher gets the first element that matches the matcher by testing the
+// element itself and traversing up through its ancestors in the DOM tree.
+func (s *Selection) ClosestMatcher(m Matcher) *Selection {
+ return pushStack(s, mapNodes(s.Nodes, func(i int, n *html.Node) []*html.Node {
+ // For each node in the selection, test the node itself, then each parent
+ // until a match is found.
+ for ; n != nil; n = n.Parent {
+ if m.Match(n) {
+ return []*html.Node{n}
+ }
+ }
+ return nil
+ }))
+}
+
+// ClosestNodes gets the first element that matches one of the nodes by testing the
+// element itself and traversing up through its ancestors in the DOM tree.
+func (s *Selection) ClosestNodes(nodes ...*html.Node) *Selection {
+ set := make(map[*html.Node]bool)
+ for _, n := range nodes {
+ set[n] = true
+ }
+ return pushStack(s, mapNodes(s.Nodes, func(i int, n *html.Node) []*html.Node {
+ // For each node in the selection, test the node itself, then each parent
+ // until a match is found.
+ for ; n != nil; n = n.Parent {
+ if set[n] {
+ return []*html.Node{n}
+ }
+ }
+ return nil
+ }))
+}
+
+// ClosestSelection gets the first element that matches one of the nodes in the
+// Selection by testing the element itself and traversing up through its ancestors
+// in the DOM tree.
+func (s *Selection) ClosestSelection(sel *Selection) *Selection {
+ if sel == nil {
+ return pushStack(s, nil)
+ }
+ return s.ClosestNodes(sel.Nodes...)
+}
+
+// Parents gets the ancestors of each element in the current Selection. It
+// returns a new Selection object with the matched elements.
+func (s *Selection) Parents() *Selection {
+ return pushStack(s, getParentsNodes(s.Nodes, nil, nil))
+}
+
+// ParentsFiltered gets the ancestors of each element in the current
+// Selection. It returns a new Selection object with the matched elements.
+func (s *Selection) ParentsFiltered(selector string) *Selection {
+ return filterAndPush(s, getParentsNodes(s.Nodes, nil, nil), compileMatcher(selector))
+}
+
+// ParentsMatcher gets the ancestors of each element in the current
+// Selection. It returns a new Selection object with the matched elements.
+func (s *Selection) ParentsMatcher(m Matcher) *Selection {
+ return filterAndPush(s, getParentsNodes(s.Nodes, nil, nil), m)
+}
+
+// ParentsUntil gets the ancestors of each element in the Selection, up to but
+// not including the element matched by the selector. It returns a new Selection
+// object containing the matched elements.
+func (s *Selection) ParentsUntil(selector string) *Selection {
+ return pushStack(s, getParentsNodes(s.Nodes, compileMatcher(selector), nil))
+}
+
+// ParentsUntilMatcher gets the ancestors of each element in the Selection, up to but
+// not including the element matched by the matcher. It returns a new Selection
+// object containing the matched elements.
+func (s *Selection) ParentsUntilMatcher(m Matcher) *Selection {
+ return pushStack(s, getParentsNodes(s.Nodes, m, nil))
+}
+
+// ParentsUntilSelection gets the ancestors of each element in the Selection,
+// up to but not including the elements in the specified Selection. It returns a
+// new Selection object containing the matched elements.
+func (s *Selection) ParentsUntilSelection(sel *Selection) *Selection {
+ if sel == nil {
+ return s.Parents()
+ }
+ return s.ParentsUntilNodes(sel.Nodes...)
+}
+
+// ParentsUntilNodes gets the ancestors of each element in the Selection,
+// up to but not including the specified nodes. It returns a
+// new Selection object containing the matched elements.
+func (s *Selection) ParentsUntilNodes(nodes ...*html.Node) *Selection {
+ return pushStack(s, getParentsNodes(s.Nodes, nil, nodes))
+}
+
+// ParentsFilteredUntil is like ParentsUntil, with the option to filter the
+// results based on a selector string. It returns a new Selection
+// object containing the matched elements.
+func (s *Selection) ParentsFilteredUntil(filterSelector, untilSelector string) *Selection {
+ return filterAndPush(s, getParentsNodes(s.Nodes, compileMatcher(untilSelector), nil), compileMatcher(filterSelector))
+}
+
+// ParentsFilteredUntilMatcher is like ParentsUntilMatcher, with the option to filter the
+// results based on a matcher. It returns a new Selection object containing the matched elements.
+func (s *Selection) ParentsFilteredUntilMatcher(filter, until Matcher) *Selection {
+ return filterAndPush(s, getParentsNodes(s.Nodes, until, nil), filter)
+}
+
+// ParentsFilteredUntilSelection is like ParentsUntilSelection, with the
+// option to filter the results based on a selector string. It returns a new
+// Selection object containing the matched elements.
+func (s *Selection) ParentsFilteredUntilSelection(filterSelector string, sel *Selection) *Selection {
+ return s.ParentsMatcherUntilSelection(compileMatcher(filterSelector), sel)
+}
+
+// ParentsMatcherUntilSelection is like ParentsUntilSelection, with the
+// option to filter the results based on a matcher. It returns a new
+// Selection object containing the matched elements.
+func (s *Selection) ParentsMatcherUntilSelection(filter Matcher, sel *Selection) *Selection {
+ if sel == nil {
+ return s.ParentsMatcher(filter)
+ }
+ return s.ParentsMatcherUntilNodes(filter, sel.Nodes...)
+}
+
+// ParentsFilteredUntilNodes is like ParentsUntilNodes, with the
+// option to filter the results based on a selector string. It returns a new
+// Selection object containing the matched elements.
+func (s *Selection) ParentsFilteredUntilNodes(filterSelector string, nodes ...*html.Node) *Selection {
+ return filterAndPush(s, getParentsNodes(s.Nodes, nil, nodes), compileMatcher(filterSelector))
+}
+
+// ParentsMatcherUntilNodes is like ParentsUntilNodes, with the
+// option to filter the results based on a matcher. It returns a new
+// Selection object containing the matched elements.
+func (s *Selection) ParentsMatcherUntilNodes(filter Matcher, nodes ...*html.Node) *Selection {
+ return filterAndPush(s, getParentsNodes(s.Nodes, nil, nodes), filter)
+}
+
+// Siblings gets the siblings of each element in the Selection. It returns
+// a new Selection object containing the matched elements.
+func (s *Selection) Siblings() *Selection {
+ return pushStack(s, getSiblingNodes(s.Nodes, siblingAll, nil, nil))
+}
+
+// SiblingsFiltered gets the siblings of each element in the Selection
+// filtered by a selector. It returns a new Selection object containing the
+// matched elements.
+func (s *Selection) SiblingsFiltered(selector string) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingAll, nil, nil), compileMatcher(selector))
+}
+
+// SiblingsMatcher gets the siblings of each element in the Selection
+// filtered by a matcher. It returns a new Selection object containing the
+// matched elements.
+func (s *Selection) SiblingsMatcher(m Matcher) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingAll, nil, nil), m)
+}
+
+// Next gets the immediately following sibling of each element in the
+// Selection. It returns a new Selection object containing the matched elements.
+func (s *Selection) Next() *Selection {
+ return pushStack(s, getSiblingNodes(s.Nodes, siblingNext, nil, nil))
+}
+
+// NextFiltered gets the immediately following sibling of each element in the
+// Selection filtered by a selector. It returns a new Selection object
+// containing the matched elements.
+func (s *Selection) NextFiltered(selector string) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingNext, nil, nil), compileMatcher(selector))
+}
+
+// NextMatcher gets the immediately following sibling of each element in the
+// Selection filtered by a matcher. It returns a new Selection object
+// containing the matched elements.
+func (s *Selection) NextMatcher(m Matcher) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingNext, nil, nil), m)
+}
+
+// NextAll gets all the following siblings of each element in the
+// Selection. It returns a new Selection object containing the matched elements.
+func (s *Selection) NextAll() *Selection {
+ return pushStack(s, getSiblingNodes(s.Nodes, siblingNextAll, nil, nil))
+}
+
+// NextAllFiltered gets all the following siblings of each element in the
+// Selection filtered by a selector. It returns a new Selection object
+// containing the matched elements.
+func (s *Selection) NextAllFiltered(selector string) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingNextAll, nil, nil), compileMatcher(selector))
+}
+
+// NextAllMatcher gets all the following siblings of each element in the
+// Selection filtered by a matcher. It returns a new Selection object
+// containing the matched elements.
+func (s *Selection) NextAllMatcher(m Matcher) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingNextAll, nil, nil), m)
+}
+
+// Prev gets the immediately preceding sibling of each element in the
+// Selection. It returns a new Selection object containing the matched elements.
+func (s *Selection) Prev() *Selection {
+ return pushStack(s, getSiblingNodes(s.Nodes, siblingPrev, nil, nil))
+}
+
+// PrevFiltered gets the immediately preceding sibling of each element in the
+// Selection filtered by a selector. It returns a new Selection object
+// containing the matched elements.
+func (s *Selection) PrevFiltered(selector string) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingPrev, nil, nil), compileMatcher(selector))
+}
+
+// PrevMatcher gets the immediately preceding sibling of each element in the
+// Selection filtered by a matcher. It returns a new Selection object
+// containing the matched elements.
+func (s *Selection) PrevMatcher(m Matcher) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingPrev, nil, nil), m)
+}
+
+// PrevAll gets all the preceding siblings of each element in the
+// Selection. It returns a new Selection object containing the matched elements.
+func (s *Selection) PrevAll() *Selection {
+ return pushStack(s, getSiblingNodes(s.Nodes, siblingPrevAll, nil, nil))
+}
+
+// PrevAllFiltered gets all the preceding siblings of each element in the
+// Selection filtered by a selector. It returns a new Selection object
+// containing the matched elements.
+func (s *Selection) PrevAllFiltered(selector string) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingPrevAll, nil, nil), compileMatcher(selector))
+}
+
+// PrevAllMatcher gets all the preceding siblings of each element in the
+// Selection filtered by a matcher. It returns a new Selection object
+// containing the matched elements.
+func (s *Selection) PrevAllMatcher(m Matcher) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingPrevAll, nil, nil), m)
+}
+
+// NextUntil gets all following siblings of each element up to but not
+// including the element matched by the selector. It returns a new Selection
+// object containing the matched elements.
+func (s *Selection) NextUntil(selector string) *Selection {
+ return pushStack(s, getSiblingNodes(s.Nodes, siblingNextUntil,
+ compileMatcher(selector), nil))
+}
+
+// NextUntilMatcher gets all following siblings of each element up to but not
+// including the element matched by the matcher. It returns a new Selection
+// object containing the matched elements.
+func (s *Selection) NextUntilMatcher(m Matcher) *Selection {
+ return pushStack(s, getSiblingNodes(s.Nodes, siblingNextUntil,
+ m, nil))
+}
+
+// NextUntilSelection gets all following siblings of each element up to but not
+// including the element matched by the Selection. It returns a new Selection
+// object containing the matched elements.
+func (s *Selection) NextUntilSelection(sel *Selection) *Selection {
+ if sel == nil {
+ return s.NextAll()
+ }
+ return s.NextUntilNodes(sel.Nodes...)
+}
+
+// NextUntilNodes gets all following siblings of each element up to but not
+// including the element matched by the nodes. It returns a new Selection
+// object containing the matched elements.
+func (s *Selection) NextUntilNodes(nodes ...*html.Node) *Selection {
+ return pushStack(s, getSiblingNodes(s.Nodes, siblingNextUntil,
+ nil, nodes))
+}
+
+// PrevUntil gets all preceding siblings of each element up to but not
+// including the element matched by the selector. It returns a new Selection
+// object containing the matched elements.
+func (s *Selection) PrevUntil(selector string) *Selection {
+ return pushStack(s, getSiblingNodes(s.Nodes, siblingPrevUntil,
+ compileMatcher(selector), nil))
+}
+
+// PrevUntilMatcher gets all preceding siblings of each element up to but not
+// including the element matched by the matcher. It returns a new Selection
+// object containing the matched elements.
+func (s *Selection) PrevUntilMatcher(m Matcher) *Selection {
+ return pushStack(s, getSiblingNodes(s.Nodes, siblingPrevUntil,
+ m, nil))
+}
+
+// PrevUntilSelection gets all preceding siblings of each element up to but not
+// including the element matched by the Selection. It returns a new Selection
+// object containing the matched elements.
+func (s *Selection) PrevUntilSelection(sel *Selection) *Selection {
+ if sel == nil {
+ return s.PrevAll()
+ }
+ return s.PrevUntilNodes(sel.Nodes...)
+}
+
+// PrevUntilNodes gets all preceding siblings of each element up to but not
+// including the element matched by the nodes. It returns a new Selection
+// object containing the matched elements.
+func (s *Selection) PrevUntilNodes(nodes ...*html.Node) *Selection {
+ return pushStack(s, getSiblingNodes(s.Nodes, siblingPrevUntil,
+ nil, nodes))
+}
+
+// NextFilteredUntil is like NextUntil, with the option to filter
+// the results based on a selector string.
+// It returns a new Selection object containing the matched elements.
+func (s *Selection) NextFilteredUntil(filterSelector, untilSelector string) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingNextUntil,
+ compileMatcher(untilSelector), nil), compileMatcher(filterSelector))
+}
+
+// NextFilteredUntilMatcher is like NextUntilMatcher, with the option to filter
+// the results based on a matcher.
+// It returns a new Selection object containing the matched elements.
+func (s *Selection) NextFilteredUntilMatcher(filter, until Matcher) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingNextUntil,
+ until, nil), filter)
+}
+
+// NextFilteredUntilSelection is like NextUntilSelection, with the
+// option to filter the results based on a selector string. It returns a new
+// Selection object containing the matched elements.
+func (s *Selection) NextFilteredUntilSelection(filterSelector string, sel *Selection) *Selection {
+ return s.NextMatcherUntilSelection(compileMatcher(filterSelector), sel)
+}
+
+// NextMatcherUntilSelection is like NextUntilSelection, with the
+// option to filter the results based on a matcher. It returns a new
+// Selection object containing the matched elements.
+func (s *Selection) NextMatcherUntilSelection(filter Matcher, sel *Selection) *Selection {
+ if sel == nil {
+ return s.NextMatcher(filter)
+ }
+ return s.NextMatcherUntilNodes(filter, sel.Nodes...)
+}
+
+// NextFilteredUntilNodes is like NextUntilNodes, with the
+// option to filter the results based on a selector string. It returns a new
+// Selection object containing the matched elements.
+func (s *Selection) NextFilteredUntilNodes(filterSelector string, nodes ...*html.Node) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingNextUntil,
+ nil, nodes), compileMatcher(filterSelector))
+}
+
+// NextMatcherUntilNodes is like NextUntilNodes, with the
+// option to filter the results based on a matcher. It returns a new
+// Selection object containing the matched elements.
+func (s *Selection) NextMatcherUntilNodes(filter Matcher, nodes ...*html.Node) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingNextUntil,
+ nil, nodes), filter)
+}
+
+// PrevFilteredUntil is like PrevUntil, with the option to filter
+// the results based on a selector string.
+// It returns a new Selection object containing the matched elements.
+func (s *Selection) PrevFilteredUntil(filterSelector, untilSelector string) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingPrevUntil,
+ compileMatcher(untilSelector), nil), compileMatcher(filterSelector))
+}
+
+// PrevFilteredUntilMatcher is like PrevUntilMatcher, with the option to filter
+// the results based on a matcher.
+// It returns a new Selection object containing the matched elements.
+func (s *Selection) PrevFilteredUntilMatcher(filter, until Matcher) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingPrevUntil,
+ until, nil), filter)
+}
+
+// PrevFilteredUntilSelection is like PrevUntilSelection, with the
+// option to filter the results based on a selector string. It returns a new
+// Selection object containing the matched elements.
+func (s *Selection) PrevFilteredUntilSelection(filterSelector string, sel *Selection) *Selection {
+ return s.PrevMatcherUntilSelection(compileMatcher(filterSelector), sel)
+}
+
+// PrevMatcherUntilSelection is like PrevUntilSelection, with the
+// option to filter the results based on a matcher. It returns a new
+// Selection object containing the matched elements.
+func (s *Selection) PrevMatcherUntilSelection(filter Matcher, sel *Selection) *Selection {
+ if sel == nil {
+ return s.PrevMatcher(filter)
+ }
+ return s.PrevMatcherUntilNodes(filter, sel.Nodes...)
+}
+
+// PrevFilteredUntilNodes is like PrevUntilNodes, with the
+// option to filter the results based on a selector string. It returns a new
+// Selection object containing the matched elements.
+func (s *Selection) PrevFilteredUntilNodes(filterSelector string, nodes ...*html.Node) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingPrevUntil,
+ nil, nodes), compileMatcher(filterSelector))
+}
+
+// PrevMatcherUntilNodes is like PrevUntilNodes, with the
+// option to filter the results based on a matcher. It returns a new
+// Selection object containing the matched elements.
+func (s *Selection) PrevMatcherUntilNodes(filter Matcher, nodes ...*html.Node) *Selection {
+ return filterAndPush(s, getSiblingNodes(s.Nodes, siblingPrevUntil,
+ nil, nodes), filter)
+}
+
+// Filter and push filters the nodes based on a matcher, and pushes the results
+// on the stack, with the srcSel as previous selection.
+func filterAndPush(srcSel *Selection, nodes []*html.Node, m Matcher) *Selection {
+ // Create a temporary Selection with the specified nodes to filter using winnow
+ sel := &Selection{nodes, srcSel.document, nil}
+ // Filter based on matcher and push on stack
+ return pushStack(srcSel, winnow(sel, m, true))
+}
+
+// Internal implementation of Find that return raw nodes.
+func findWithMatcher(nodes []*html.Node, m Matcher) []*html.Node {
+ // Map nodes to find the matches within the children of each node
+ return mapNodes(nodes, func(i int, n *html.Node) (result []*html.Node) {
+ // Go down one level, becausejQuery's Find selects only within descendants
+ for c := n.FirstChild; c != nil; c = c.NextSibling {
+ if c.Type == html.ElementNode {
+ result = append(result, m.MatchAll(c)...)
+ }
+ }
+ return
+ })
+}
+
+// Internal implementation to get all parent nodes, stopping at the specified
+// node (or nil if no stop).
+func getParentsNodes(nodes []*html.Node, stopm Matcher, stopNodes []*html.Node) []*html.Node {
+ return mapNodes(nodes, func(i int, n *html.Node) (result []*html.Node) {
+ for p := n.Parent; p != nil; p = p.Parent {
+ sel := newSingleSelection(p, nil)
+ if stopm != nil {
+ if sel.IsMatcher(stopm) {
+ break
+ }
+ } else if len(stopNodes) > 0 {
+ if sel.IsNodes(stopNodes...) {
+ break
+ }
+ }
+ if p.Type == html.ElementNode {
+ result = append(result, p)
+ }
+ }
+ return
+ })
+}
+
+// Internal implementation of sibling nodes that return a raw slice of matches.
+func getSiblingNodes(nodes []*html.Node, st siblingType, untilm Matcher, untilNodes []*html.Node) []*html.Node {
+ var f func(*html.Node) bool
+
+ // If the requested siblings are ...Until, create the test function to
+ // determine if the until condition is reached (returns true if it is)
+ if st == siblingNextUntil || st == siblingPrevUntil {
+ f = func(n *html.Node) bool {
+ if untilm != nil {
+ // Matcher-based condition
+ sel := newSingleSelection(n, nil)
+ return sel.IsMatcher(untilm)
+ } else if len(untilNodes) > 0 {
+ // Nodes-based condition
+ sel := newSingleSelection(n, nil)
+ return sel.IsNodes(untilNodes...)
+ }
+ return false
+ }
+ }
+
+ return mapNodes(nodes, func(i int, n *html.Node) []*html.Node {
+ return getChildrenWithSiblingType(n.Parent, st, n, f)
+ })
+}
+
+// Gets the children nodes of each node in the specified slice of nodes,
+// based on the sibling type request.
+func getChildrenNodes(nodes []*html.Node, st siblingType) []*html.Node {
+ return mapNodes(nodes, func(i int, n *html.Node) []*html.Node {
+ return getChildrenWithSiblingType(n, st, nil, nil)
+ })
+}
+
+// Gets the children of the specified parent, based on the requested sibling
+// type, skipping a specified node if required.
+func getChildrenWithSiblingType(parent *html.Node, st siblingType, skipNode *html.Node,
+ untilFunc func(*html.Node) bool) (result []*html.Node) {
+
+ // Create the iterator function
+ var iter = func(cur *html.Node) (ret *html.Node) {
+ // Based on the sibling type requested, iterate the right way
+ for {
+ switch st {
+ case siblingAll, siblingAllIncludingNonElements:
+ if cur == nil {
+ // First iteration, start with first child of parent
+ // Skip node if required
+ if ret = parent.FirstChild; ret == skipNode && skipNode != nil {
+ ret = skipNode.NextSibling
+ }
+ } else {
+ // Skip node if required
+ if ret = cur.NextSibling; ret == skipNode && skipNode != nil {
+ ret = skipNode.NextSibling
+ }
+ }
+ case siblingPrev, siblingPrevAll, siblingPrevUntil:
+ if cur == nil {
+ // Start with previous sibling of the skip node
+ ret = skipNode.PrevSibling
+ } else {
+ ret = cur.PrevSibling
+ }
+ case siblingNext, siblingNextAll, siblingNextUntil:
+ if cur == nil {
+ // Start with next sibling of the skip node
+ ret = skipNode.NextSibling
+ } else {
+ ret = cur.NextSibling
+ }
+ default:
+ panic("Invalid sibling type.")
+ }
+ if ret == nil || ret.Type == html.ElementNode || st == siblingAllIncludingNonElements {
+ return
+ }
+ // Not a valid node, try again from this one
+ cur = ret
+ }
+ }
+
+ for c := iter(nil); c != nil; c = iter(c) {
+ // If this is an ...Until case, test before append (returns true
+ // if the until condition is reached)
+ if st == siblingNextUntil || st == siblingPrevUntil {
+ if untilFunc(c) {
+ return
+ }
+ }
+ result = append(result, c)
+ if st == siblingNext || st == siblingPrev {
+ // Only one node was requested (immediate next or previous), so exit
+ return
+ }
+ }
+ return
+}
+
+// Internal implementation of parent nodes that return a raw slice of Nodes.
+func getParentNodes(nodes []*html.Node) []*html.Node {
+ return mapNodes(nodes, func(i int, n *html.Node) []*html.Node {
+ if n.Parent != nil && n.Parent.Type == html.ElementNode {
+ return []*html.Node{n.Parent}
+ }
+ return nil
+ })
+}
+
+// Internal map function used by many traversing methods. Takes the source nodes
+// to iterate on and the mapping function that returns an array of nodes.
+// Returns an array of nodes mapped by calling the callback function once for
+// each node in the source nodes.
+func mapNodes(nodes []*html.Node, f func(int, *html.Node) []*html.Node) (result []*html.Node) {
+ set := make(map[*html.Node]bool)
+ for i, n := range nodes {
+ if vals := f(i, n); len(vals) > 0 {
+ result = appendWithoutDuplicates(result, vals, set)
+ }
+ }
+ return result
+}
diff --git a/vendor/github.com/PuerkitoBio/goquery/traversal_test.go b/vendor/github.com/PuerkitoBio/goquery/traversal_test.go
new file mode 100644
index 00000000..04383a41
--- /dev/null
+++ b/vendor/github.com/PuerkitoBio/goquery/traversal_test.go
@@ -0,0 +1,793 @@
+package goquery
+
+import (
+ "strings"
+ "testing"
+)
+
+func TestFind(t *testing.T) {
+ sel := Doc().Find("div.row-fluid")
+ assertLength(t, sel.Nodes, 9)
+}
+
+func TestFindRollback(t *testing.T) {
+ sel := Doc().Find("div.row-fluid")
+ sel2 := sel.Find("a").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestFindNotSelf(t *testing.T) {
+ sel := Doc().Find("h1").Find("h1")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestFindInvalid(t *testing.T) {
+ sel := Doc().Find(":+ ^")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestFindBig(t *testing.T) {
+ doc := DocW()
+ sel := doc.Find("li")
+ assertLength(t, sel.Nodes, 373)
+ sel2 := doc.Find("span")
+ assertLength(t, sel2.Nodes, 448)
+ sel3 := sel.FindSelection(sel2)
+ assertLength(t, sel3.Nodes, 248)
+}
+
+func TestChainedFind(t *testing.T) {
+ sel := Doc().Find("div.hero-unit").Find(".row-fluid")
+ assertLength(t, sel.Nodes, 4)
+}
+
+func TestChainedFindInvalid(t *testing.T) {
+ sel := Doc().Find("div.hero-unit").Find("")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestChildren(t *testing.T) {
+ sel := Doc().Find(".pvk-content").Children()
+ assertLength(t, sel.Nodes, 5)
+}
+
+func TestChildrenRollback(t *testing.T) {
+ sel := Doc().Find(".pvk-content")
+ sel2 := sel.Children().End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestContents(t *testing.T) {
+ sel := Doc().Find(".pvk-content").Contents()
+ assertLength(t, sel.Nodes, 13)
+}
+
+func TestContentsRollback(t *testing.T) {
+ sel := Doc().Find(".pvk-content")
+ sel2 := sel.Contents().End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestChildrenFiltered(t *testing.T) {
+ sel := Doc().Find(".pvk-content").ChildrenFiltered(".hero-unit")
+ assertLength(t, sel.Nodes, 1)
+}
+
+func TestChildrenFilteredInvalid(t *testing.T) {
+ sel := Doc().Find(".pvk-content").ChildrenFiltered("")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestChildrenFilteredRollback(t *testing.T) {
+ sel := Doc().Find(".pvk-content")
+ sel2 := sel.ChildrenFiltered(".hero-unit").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestContentsFiltered(t *testing.T) {
+ sel := Doc().Find(".pvk-content").ContentsFiltered(".hero-unit")
+ assertLength(t, sel.Nodes, 1)
+}
+
+func TestContentsFilteredInvalid(t *testing.T) {
+ sel := Doc().Find(".pvk-content").ContentsFiltered("~")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestContentsFilteredRollback(t *testing.T) {
+ sel := Doc().Find(".pvk-content")
+ sel2 := sel.ContentsFiltered(".hero-unit").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestChildrenFilteredNone(t *testing.T) {
+ sel := Doc().Find(".pvk-content").ChildrenFiltered("a.btn")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestParent(t *testing.T) {
+ sel := Doc().Find(".container-fluid").Parent()
+ assertLength(t, sel.Nodes, 3)
+}
+
+func TestParentRollback(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := sel.Parent().End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestParentBody(t *testing.T) {
+ sel := Doc().Find("body").Parent()
+ assertLength(t, sel.Nodes, 1)
+}
+
+func TestParentFiltered(t *testing.T) {
+ sel := Doc().Find(".container-fluid").ParentFiltered(".hero-unit")
+ assertLength(t, sel.Nodes, 1)
+ assertClass(t, sel, "hero-unit")
+}
+
+func TestParentFilteredInvalid(t *testing.T) {
+ sel := Doc().Find(".container-fluid").ParentFiltered("")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestParentFilteredRollback(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := sel.ParentFiltered(".hero-unit").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestParents(t *testing.T) {
+ sel := Doc().Find(".container-fluid").Parents()
+ assertLength(t, sel.Nodes, 8)
+}
+
+func TestParentsOrder(t *testing.T) {
+ sel := Doc().Find("#cf2").Parents()
+ assertLength(t, sel.Nodes, 6)
+ assertSelectionIs(t, sel, ".hero-unit", ".pvk-content", "div.row-fluid", "#cf1", "body", "html")
+}
+
+func TestParentsRollback(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := sel.Parents().End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestParentsFiltered(t *testing.T) {
+ sel := Doc().Find(".container-fluid").ParentsFiltered("body")
+ assertLength(t, sel.Nodes, 1)
+}
+
+func TestParentsFilteredInvalid(t *testing.T) {
+ sel := Doc().Find(".container-fluid").ParentsFiltered("")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestParentsFilteredRollback(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := sel.ParentsFiltered("body").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestParentsUntil(t *testing.T) {
+ sel := Doc().Find(".container-fluid").ParentsUntil("body")
+ assertLength(t, sel.Nodes, 6)
+}
+
+func TestParentsUntilInvalid(t *testing.T) {
+ sel := Doc().Find(".container-fluid").ParentsUntil("")
+ assertLength(t, sel.Nodes, 8)
+}
+
+func TestParentsUntilRollback(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := sel.ParentsUntil("body").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestParentsUntilSelection(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := Doc().Find(".pvk-content")
+ sel = sel.ParentsUntilSelection(sel2)
+ assertLength(t, sel.Nodes, 3)
+}
+
+func TestParentsUntilSelectionRollback(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := Doc().Find(".pvk-content")
+ sel2 = sel.ParentsUntilSelection(sel2).End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestParentsUntilNodes(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := Doc().Find(".pvk-content, .hero-unit")
+ sel = sel.ParentsUntilNodes(sel2.Nodes...)
+ assertLength(t, sel.Nodes, 2)
+}
+
+func TestParentsUntilNodesRollback(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := Doc().Find(".pvk-content, .hero-unit")
+ sel2 = sel.ParentsUntilNodes(sel2.Nodes...).End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestParentsFilteredUntil(t *testing.T) {
+ sel := Doc().Find(".container-fluid").ParentsFilteredUntil(".pvk-content", "body")
+ assertLength(t, sel.Nodes, 2)
+}
+
+func TestParentsFilteredUntilInvalid(t *testing.T) {
+ sel := Doc().Find(".container-fluid").ParentsFilteredUntil("", "")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestParentsFilteredUntilRollback(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := sel.ParentsFilteredUntil(".pvk-content", "body").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestParentsFilteredUntilSelection(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := Doc().Find(".row-fluid")
+ sel = sel.ParentsFilteredUntilSelection("div", sel2)
+ assertLength(t, sel.Nodes, 3)
+}
+
+func TestParentsFilteredUntilSelectionRollback(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := Doc().Find(".row-fluid")
+ sel2 = sel.ParentsFilteredUntilSelection("div", sel2).End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestParentsFilteredUntilNodes(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := Doc().Find(".row-fluid")
+ sel = sel.ParentsFilteredUntilNodes("body", sel2.Nodes...)
+ assertLength(t, sel.Nodes, 1)
+}
+
+func TestParentsFilteredUntilNodesRollback(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := Doc().Find(".row-fluid")
+ sel2 = sel.ParentsFilteredUntilNodes("body", sel2.Nodes...).End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestSiblings(t *testing.T) {
+ sel := Doc().Find("h1").Siblings()
+ assertLength(t, sel.Nodes, 1)
+}
+
+func TestSiblingsRollback(t *testing.T) {
+ sel := Doc().Find("h1")
+ sel2 := sel.Siblings().End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestSiblings2(t *testing.T) {
+ sel := Doc().Find(".pvk-gutter").Siblings()
+ assertLength(t, sel.Nodes, 9)
+}
+
+func TestSiblings3(t *testing.T) {
+ sel := Doc().Find("body>.container-fluid").Siblings()
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestSiblingsFiltered(t *testing.T) {
+ sel := Doc().Find(".pvk-gutter").SiblingsFiltered(".pvk-content")
+ assertLength(t, sel.Nodes, 3)
+}
+
+func TestSiblingsFilteredInvalid(t *testing.T) {
+ sel := Doc().Find(".pvk-gutter").SiblingsFiltered("")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestSiblingsFilteredRollback(t *testing.T) {
+ sel := Doc().Find(".pvk-gutter")
+ sel2 := sel.SiblingsFiltered(".pvk-content").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestNext(t *testing.T) {
+ sel := Doc().Find("h1").Next()
+ assertLength(t, sel.Nodes, 1)
+}
+
+func TestNextRollback(t *testing.T) {
+ sel := Doc().Find("h1")
+ sel2 := sel.Next().End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestNext2(t *testing.T) {
+ sel := Doc().Find(".close").Next()
+ assertLength(t, sel.Nodes, 1)
+}
+
+func TestNextNone(t *testing.T) {
+ sel := Doc().Find("small").Next()
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestNextFiltered(t *testing.T) {
+ sel := Doc().Find(".container-fluid").NextFiltered("div")
+ assertLength(t, sel.Nodes, 2)
+}
+
+func TestNextFilteredInvalid(t *testing.T) {
+ sel := Doc().Find(".container-fluid").NextFiltered("")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestNextFilteredRollback(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := sel.NextFiltered("div").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestNextFiltered2(t *testing.T) {
+ sel := Doc().Find(".container-fluid").NextFiltered("[ng-view]")
+ assertLength(t, sel.Nodes, 1)
+}
+
+func TestPrev(t *testing.T) {
+ sel := Doc().Find(".red").Prev()
+ assertLength(t, sel.Nodes, 1)
+ assertClass(t, sel, "green")
+}
+
+func TestPrevRollback(t *testing.T) {
+ sel := Doc().Find(".red")
+ sel2 := sel.Prev().End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestPrev2(t *testing.T) {
+ sel := Doc().Find(".row-fluid").Prev()
+ assertLength(t, sel.Nodes, 5)
+}
+
+func TestPrevNone(t *testing.T) {
+ sel := Doc().Find("h2").Prev()
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestPrevFiltered(t *testing.T) {
+ sel := Doc().Find(".row-fluid").PrevFiltered(".row-fluid")
+ assertLength(t, sel.Nodes, 5)
+}
+
+func TestPrevFilteredInvalid(t *testing.T) {
+ sel := Doc().Find(".row-fluid").PrevFiltered("")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestPrevFilteredRollback(t *testing.T) {
+ sel := Doc().Find(".row-fluid")
+ sel2 := sel.PrevFiltered(".row-fluid").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestNextAll(t *testing.T) {
+ sel := Doc().Find("#cf2 div:nth-child(1)").NextAll()
+ assertLength(t, sel.Nodes, 3)
+}
+
+func TestNextAllRollback(t *testing.T) {
+ sel := Doc().Find("#cf2 div:nth-child(1)")
+ sel2 := sel.NextAll().End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestNextAll2(t *testing.T) {
+ sel := Doc().Find("div[ng-cloak]").NextAll()
+ assertLength(t, sel.Nodes, 1)
+}
+
+func TestNextAllNone(t *testing.T) {
+ sel := Doc().Find(".footer").NextAll()
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestNextAllFiltered(t *testing.T) {
+ sel := Doc().Find("#cf2 .row-fluid").NextAllFiltered("[ng-cloak]")
+ assertLength(t, sel.Nodes, 2)
+}
+
+func TestNextAllFilteredInvalid(t *testing.T) {
+ sel := Doc().Find("#cf2 .row-fluid").NextAllFiltered("")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestNextAllFilteredRollback(t *testing.T) {
+ sel := Doc().Find("#cf2 .row-fluid")
+ sel2 := sel.NextAllFiltered("[ng-cloak]").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestNextAllFiltered2(t *testing.T) {
+ sel := Doc().Find(".close").NextAllFiltered("h4")
+ assertLength(t, sel.Nodes, 1)
+}
+
+func TestPrevAll(t *testing.T) {
+ sel := Doc().Find("[ng-view]").PrevAll()
+ assertLength(t, sel.Nodes, 2)
+}
+
+func TestPrevAllOrder(t *testing.T) {
+ sel := Doc().Find("[ng-view]").PrevAll()
+ assertLength(t, sel.Nodes, 2)
+ assertSelectionIs(t, sel, "#cf4", "#cf3")
+}
+
+func TestPrevAllRollback(t *testing.T) {
+ sel := Doc().Find("[ng-view]")
+ sel2 := sel.PrevAll().End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestPrevAll2(t *testing.T) {
+ sel := Doc().Find(".pvk-gutter").PrevAll()
+ assertLength(t, sel.Nodes, 6)
+}
+
+func TestPrevAllFiltered(t *testing.T) {
+ sel := Doc().Find(".pvk-gutter").PrevAllFiltered(".pvk-content")
+ assertLength(t, sel.Nodes, 3)
+}
+
+func TestPrevAllFilteredInvalid(t *testing.T) {
+ sel := Doc().Find(".pvk-gutter").PrevAllFiltered("")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestPrevAllFilteredRollback(t *testing.T) {
+ sel := Doc().Find(".pvk-gutter")
+ sel2 := sel.PrevAllFiltered(".pvk-content").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestNextUntil(t *testing.T) {
+ sel := Doc().Find(".alert a").NextUntil("p")
+ assertLength(t, sel.Nodes, 1)
+ assertSelectionIs(t, sel, "h4")
+}
+
+func TestNextUntilInvalid(t *testing.T) {
+ sel := Doc().Find(".alert a").NextUntil("")
+ assertLength(t, sel.Nodes, 2)
+}
+
+func TestNextUntil2(t *testing.T) {
+ sel := Doc().Find("#cf2-1").NextUntil("[ng-cloak]")
+ assertLength(t, sel.Nodes, 1)
+ assertSelectionIs(t, sel, "#cf2-2")
+}
+
+func TestNextUntilOrder(t *testing.T) {
+ sel := Doc().Find("#cf2-1").NextUntil("#cf2-4")
+ assertLength(t, sel.Nodes, 2)
+ assertSelectionIs(t, sel, "#cf2-2", "#cf2-3")
+}
+
+func TestNextUntilRollback(t *testing.T) {
+ sel := Doc().Find("#cf2-1")
+ sel2 := sel.PrevUntil("#cf2-4").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestNextUntilSelection(t *testing.T) {
+ sel := Doc2().Find("#n2")
+ sel2 := Doc2().Find("#n4")
+ sel2 = sel.NextUntilSelection(sel2)
+ assertLength(t, sel2.Nodes, 1)
+ assertSelectionIs(t, sel2, "#n3")
+}
+
+func TestNextUntilSelectionRollback(t *testing.T) {
+ sel := Doc2().Find("#n2")
+ sel2 := Doc2().Find("#n4")
+ sel2 = sel.NextUntilSelection(sel2).End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestNextUntilNodes(t *testing.T) {
+ sel := Doc2().Find("#n2")
+ sel2 := Doc2().Find("#n5")
+ sel2 = sel.NextUntilNodes(sel2.Nodes...)
+ assertLength(t, sel2.Nodes, 2)
+ assertSelectionIs(t, sel2, "#n3", "#n4")
+}
+
+func TestNextUntilNodesRollback(t *testing.T) {
+ sel := Doc2().Find("#n2")
+ sel2 := Doc2().Find("#n5")
+ sel2 = sel.NextUntilNodes(sel2.Nodes...).End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestPrevUntil(t *testing.T) {
+ sel := Doc().Find(".alert p").PrevUntil("a")
+ assertLength(t, sel.Nodes, 1)
+ assertSelectionIs(t, sel, "h4")
+}
+
+func TestPrevUntilInvalid(t *testing.T) {
+ sel := Doc().Find(".alert p").PrevUntil("")
+ assertLength(t, sel.Nodes, 2)
+}
+
+func TestPrevUntil2(t *testing.T) {
+ sel := Doc().Find("[ng-cloak]").PrevUntil(":not([ng-cloak])")
+ assertLength(t, sel.Nodes, 1)
+ assertSelectionIs(t, sel, "[ng-cloak]")
+}
+
+func TestPrevUntilOrder(t *testing.T) {
+ sel := Doc().Find("#cf2-4").PrevUntil("#cf2-1")
+ assertLength(t, sel.Nodes, 2)
+ assertSelectionIs(t, sel, "#cf2-3", "#cf2-2")
+}
+
+func TestPrevUntilRollback(t *testing.T) {
+ sel := Doc().Find("#cf2-4")
+ sel2 := sel.PrevUntil("#cf2-1").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestPrevUntilSelection(t *testing.T) {
+ sel := Doc2().Find("#n4")
+ sel2 := Doc2().Find("#n2")
+ sel2 = sel.PrevUntilSelection(sel2)
+ assertLength(t, sel2.Nodes, 1)
+ assertSelectionIs(t, sel2, "#n3")
+}
+
+func TestPrevUntilSelectionRollback(t *testing.T) {
+ sel := Doc2().Find("#n4")
+ sel2 := Doc2().Find("#n2")
+ sel2 = sel.PrevUntilSelection(sel2).End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestPrevUntilNodes(t *testing.T) {
+ sel := Doc2().Find("#n5")
+ sel2 := Doc2().Find("#n2")
+ sel2 = sel.PrevUntilNodes(sel2.Nodes...)
+ assertLength(t, sel2.Nodes, 2)
+ assertSelectionIs(t, sel2, "#n4", "#n3")
+}
+
+func TestPrevUntilNodesRollback(t *testing.T) {
+ sel := Doc2().Find("#n5")
+ sel2 := Doc2().Find("#n2")
+ sel2 = sel.PrevUntilNodes(sel2.Nodes...).End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestNextFilteredUntil(t *testing.T) {
+ sel := Doc2().Find(".two").NextFilteredUntil(".even", ".six")
+ assertLength(t, sel.Nodes, 4)
+ assertSelectionIs(t, sel, "#n3", "#n5", "#nf3", "#nf5")
+}
+
+func TestNextFilteredUntilInvalid(t *testing.T) {
+ sel := Doc2().Find(".two").NextFilteredUntil("", "")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestNextFilteredUntilRollback(t *testing.T) {
+ sel := Doc2().Find(".two")
+ sel2 := sel.NextFilteredUntil(".even", ".six").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestNextFilteredUntilSelection(t *testing.T) {
+ sel := Doc2().Find(".even")
+ sel2 := Doc2().Find(".five")
+ sel = sel.NextFilteredUntilSelection(".even", sel2)
+ assertLength(t, sel.Nodes, 2)
+ assertSelectionIs(t, sel, "#n3", "#nf3")
+}
+
+func TestNextFilteredUntilSelectionRollback(t *testing.T) {
+ sel := Doc2().Find(".even")
+ sel2 := Doc2().Find(".five")
+ sel3 := sel.NextFilteredUntilSelection(".even", sel2).End()
+ assertEqual(t, sel, sel3)
+}
+
+func TestNextFilteredUntilNodes(t *testing.T) {
+ sel := Doc2().Find(".even")
+ sel2 := Doc2().Find(".four")
+ sel = sel.NextFilteredUntilNodes(".odd", sel2.Nodes...)
+ assertLength(t, sel.Nodes, 4)
+ assertSelectionIs(t, sel, "#n2", "#n6", "#nf2", "#nf6")
+}
+
+func TestNextFilteredUntilNodesRollback(t *testing.T) {
+ sel := Doc2().Find(".even")
+ sel2 := Doc2().Find(".four")
+ sel3 := sel.NextFilteredUntilNodes(".odd", sel2.Nodes...).End()
+ assertEqual(t, sel, sel3)
+}
+
+func TestPrevFilteredUntil(t *testing.T) {
+ sel := Doc2().Find(".five").PrevFilteredUntil(".odd", ".one")
+ assertLength(t, sel.Nodes, 4)
+ assertSelectionIs(t, sel, "#n4", "#n2", "#nf4", "#nf2")
+}
+
+func TestPrevFilteredUntilInvalid(t *testing.T) {
+ sel := Doc2().Find(".five").PrevFilteredUntil("", "")
+ assertLength(t, sel.Nodes, 0)
+}
+
+func TestPrevFilteredUntilRollback(t *testing.T) {
+ sel := Doc2().Find(".four")
+ sel2 := sel.PrevFilteredUntil(".odd", ".one").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestPrevFilteredUntilSelection(t *testing.T) {
+ sel := Doc2().Find(".odd")
+ sel2 := Doc2().Find(".two")
+ sel = sel.PrevFilteredUntilSelection(".odd", sel2)
+ assertLength(t, sel.Nodes, 2)
+ assertSelectionIs(t, sel, "#n4", "#nf4")
+}
+
+func TestPrevFilteredUntilSelectionRollback(t *testing.T) {
+ sel := Doc2().Find(".even")
+ sel2 := Doc2().Find(".five")
+ sel3 := sel.PrevFilteredUntilSelection(".even", sel2).End()
+ assertEqual(t, sel, sel3)
+}
+
+func TestPrevFilteredUntilNodes(t *testing.T) {
+ sel := Doc2().Find(".even")
+ sel2 := Doc2().Find(".four")
+ sel = sel.PrevFilteredUntilNodes(".odd", sel2.Nodes...)
+ assertLength(t, sel.Nodes, 2)
+ assertSelectionIs(t, sel, "#n2", "#nf2")
+}
+
+func TestPrevFilteredUntilNodesRollback(t *testing.T) {
+ sel := Doc2().Find(".even")
+ sel2 := Doc2().Find(".four")
+ sel3 := sel.PrevFilteredUntilNodes(".odd", sel2.Nodes...).End()
+ assertEqual(t, sel, sel3)
+}
+
+func TestClosestItself(t *testing.T) {
+ sel := Doc2().Find(".three")
+ sel2 := sel.Closest(".row")
+ assertLength(t, sel2.Nodes, sel.Length())
+ assertSelectionIs(t, sel2, "#n3", "#nf3")
+}
+
+func TestClosestNoDupes(t *testing.T) {
+ sel := Doc().Find(".span12")
+ sel2 := sel.Closest(".pvk-content")
+ assertLength(t, sel2.Nodes, 1)
+ assertClass(t, sel2, "pvk-content")
+}
+
+func TestClosestNone(t *testing.T) {
+ sel := Doc().Find("h4")
+ sel2 := sel.Closest("a")
+ assertLength(t, sel2.Nodes, 0)
+}
+
+func TestClosestInvalid(t *testing.T) {
+ sel := Doc().Find("h4")
+ sel2 := sel.Closest("")
+ assertLength(t, sel2.Nodes, 0)
+}
+
+func TestClosestMany(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := sel.Closest(".pvk-content")
+ assertLength(t, sel2.Nodes, 2)
+ assertSelectionIs(t, sel2, "#pc1", "#pc2")
+}
+
+func TestClosestRollback(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := sel.Closest(".pvk-content").End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestClosestSelectionItself(t *testing.T) {
+ sel := Doc2().Find(".three")
+ sel2 := sel.ClosestSelection(Doc2().Find(".row"))
+ assertLength(t, sel2.Nodes, sel.Length())
+}
+
+func TestClosestSelectionNoDupes(t *testing.T) {
+ sel := Doc().Find(".span12")
+ sel2 := sel.ClosestSelection(Doc().Find(".pvk-content"))
+ assertLength(t, sel2.Nodes, 1)
+ assertClass(t, sel2, "pvk-content")
+}
+
+func TestClosestSelectionNone(t *testing.T) {
+ sel := Doc().Find("h4")
+ sel2 := sel.ClosestSelection(Doc().Find("a"))
+ assertLength(t, sel2.Nodes, 0)
+}
+
+func TestClosestSelectionMany(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := sel.ClosestSelection(Doc().Find(".pvk-content"))
+ assertLength(t, sel2.Nodes, 2)
+ assertSelectionIs(t, sel2, "#pc1", "#pc2")
+}
+
+func TestClosestSelectionRollback(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := sel.ClosestSelection(Doc().Find(".pvk-content")).End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestClosestNodesItself(t *testing.T) {
+ sel := Doc2().Find(".three")
+ sel2 := sel.ClosestNodes(Doc2().Find(".row").Nodes...)
+ assertLength(t, sel2.Nodes, sel.Length())
+}
+
+func TestClosestNodesNoDupes(t *testing.T) {
+ sel := Doc().Find(".span12")
+ sel2 := sel.ClosestNodes(Doc().Find(".pvk-content").Nodes...)
+ assertLength(t, sel2.Nodes, 1)
+ assertClass(t, sel2, "pvk-content")
+}
+
+func TestClosestNodesNone(t *testing.T) {
+ sel := Doc().Find("h4")
+ sel2 := sel.ClosestNodes(Doc().Find("a").Nodes...)
+ assertLength(t, sel2.Nodes, 0)
+}
+
+func TestClosestNodesMany(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := sel.ClosestNodes(Doc().Find(".pvk-content").Nodes...)
+ assertLength(t, sel2.Nodes, 2)
+ assertSelectionIs(t, sel2, "#pc1", "#pc2")
+}
+
+func TestClosestNodesRollback(t *testing.T) {
+ sel := Doc().Find(".container-fluid")
+ sel2 := sel.ClosestNodes(Doc().Find(".pvk-content").Nodes...).End()
+ assertEqual(t, sel, sel2)
+}
+
+func TestIssue26(t *testing.T) {
+ img1 := ``
+ img2 := ``
+ cases := []struct {
+ s string
+ l int
+ }{
+ {s: img1 + img2, l: 2},
+ {s: img1, l: 1},
+ {s: img2, l: 1},
+ }
+ for _, c := range cases {
+ doc, err := NewDocumentFromReader(strings.NewReader(c.s))
+ if err != nil {
+ t.Fatal(err)
+ }
+ sel := doc.Find("img[src]")
+ assertLength(t, sel.Nodes, c.l)
+ }
+}
diff --git a/vendor/github.com/PuerkitoBio/goquery/type.go b/vendor/github.com/PuerkitoBio/goquery/type.go
new file mode 100644
index 00000000..e2169fa3
--- /dev/null
+++ b/vendor/github.com/PuerkitoBio/goquery/type.go
@@ -0,0 +1,135 @@
+package goquery
+
+import (
+ "errors"
+ "io"
+ "net/http"
+ "net/url"
+
+ "github.com/andybalholm/cascadia"
+
+ "golang.org/x/net/html"
+)
+
+// Document represents an HTML document to be manipulated. Unlike jQuery, which
+// is loaded as part of a DOM document, and thus acts upon its containing
+// document, GoQuery doesn't know which HTML document to act upon. So it needs
+// to be told, and that's what the Document class is for. It holds the root
+// document node to manipulate, and can make selections on this document.
+type Document struct {
+ *Selection
+ Url *url.URL
+ rootNode *html.Node
+}
+
+// NewDocumentFromNode is a Document constructor that takes a root html Node
+// as argument.
+func NewDocumentFromNode(root *html.Node) *Document {
+ return newDocument(root, nil)
+}
+
+// NewDocument is a Document constructor that takes a string URL as argument.
+// It loads the specified document, parses it, and stores the root Document
+// node, ready to be manipulated.
+func NewDocument(url string) (*Document, error) {
+ // Load the URL
+ res, e := http.Get(url)
+ if e != nil {
+ return nil, e
+ }
+ return NewDocumentFromResponse(res)
+}
+
+// NewDocumentFromReader returns a Document from a generic reader.
+// It returns an error as second value if the reader's data cannot be parsed
+// as html. It does *not* check if the reader is also an io.Closer, so the
+// provided reader is never closed by this call, it is the responsibility
+// of the caller to close it if required.
+func NewDocumentFromReader(r io.Reader) (*Document, error) {
+ root, e := html.Parse(r)
+ if e != nil {
+ return nil, e
+ }
+ return newDocument(root, nil), nil
+}
+
+// NewDocumentFromResponse is another Document constructor that takes an http response as argument.
+// It loads the specified response's document, parses it, and stores the root Document
+// node, ready to be manipulated. The response's body is closed on return.
+func NewDocumentFromResponse(res *http.Response) (*Document, error) {
+ if res == nil {
+ return nil, errors.New("Response is nil")
+ }
+ defer res.Body.Close()
+ if res.Request == nil {
+ return nil, errors.New("Response.Request is nil")
+ }
+
+ // Parse the HTML into nodes
+ root, e := html.Parse(res.Body)
+ if e != nil {
+ return nil, e
+ }
+
+ // Create and fill the document
+ return newDocument(root, res.Request.URL), nil
+}
+
+// CloneDocument creates a deep-clone of a document.
+func CloneDocument(doc *Document) *Document {
+ return newDocument(cloneNode(doc.rootNode), doc.Url)
+}
+
+// Private constructor, make sure all fields are correctly filled.
+func newDocument(root *html.Node, url *url.URL) *Document {
+ // Create and fill the document
+ d := &Document{nil, url, root}
+ d.Selection = newSingleSelection(root, d)
+ return d
+}
+
+// Selection represents a collection of nodes matching some criteria. The
+// initial Selection can be created by using Document.Find, and then
+// manipulated using the jQuery-like chainable syntax and methods.
+type Selection struct {
+ Nodes []*html.Node
+ document *Document
+ prevSel *Selection
+}
+
+// Helper constructor to create an empty selection
+func newEmptySelection(doc *Document) *Selection {
+ return &Selection{nil, doc, nil}
+}
+
+// Helper constructor to create a selection of only one node
+func newSingleSelection(node *html.Node, doc *Document) *Selection {
+ return &Selection{[]*html.Node{node}, doc, nil}
+}
+
+// Matcher is an interface that defines the methods to match
+// HTML nodes against a compiled selector string. Cascadia's
+// Selector implements this interface.
+type Matcher interface {
+ Match(*html.Node) bool
+ MatchAll(*html.Node) []*html.Node
+ Filter([]*html.Node) []*html.Node
+}
+
+// compileMatcher compiles the selector string s and returns
+// the corresponding Matcher. If s is an invalid selector string,
+// it returns a Matcher that fails all matches.
+func compileMatcher(s string) Matcher {
+ cs, err := cascadia.Compile(s)
+ if err != nil {
+ return invalidMatcher{}
+ }
+ return cs
+}
+
+// invalidMatcher is a Matcher that always fails to match.
+type invalidMatcher struct{}
+
+func (invalidMatcher) Match(n *html.Node) bool { return false }
+func (invalidMatcher) MatchAll(n *html.Node) []*html.Node { return nil }
+func (invalidMatcher) Filter(ns []*html.Node) []*html.Node { return nil }
diff --git a/vendor/github.com/PuerkitoBio/goquery/type_test.go b/vendor/github.com/PuerkitoBio/goquery/type_test.go
new file mode 100644
index 00000000..1e82d5ee
--- /dev/null
+++ b/vendor/github.com/PuerkitoBio/goquery/type_test.go
@@ -0,0 +1,202 @@
+package goquery
+
+import (
+ "bytes"
+ "fmt"
+ "os"
+ "strings"
+ "testing"
+
+ "golang.org/x/net/html"
+)
+
+// Test helper functions and members
+var doc *Document
+var doc2 *Document
+var doc3 *Document
+var docB *Document
+var docW *Document
+
+func Doc() *Document {
+ if doc == nil {
+ doc = loadDoc("page.html")
+ }
+ return doc
+}
+
+func Doc2() *Document {
+ if doc2 == nil {
+ doc2 = loadDoc("page2.html")
+ }
+ return doc2
+}
+
+func Doc2Clone() *Document {
+ return CloneDocument(Doc2())
+}
+
+func Doc3() *Document {
+ if doc3 == nil {
+ doc3 = loadDoc("page3.html")
+ }
+ return doc3
+}
+
+func Doc3Clone() *Document {
+ return CloneDocument(Doc3())
+}
+
+func DocB() *Document {
+ if docB == nil {
+ docB = loadDoc("gotesting.html")
+ }
+ return docB
+}
+
+func DocW() *Document {
+ if docW == nil {
+ docW = loadDoc("gowiki.html")
+ }
+ return docW
+}
+
+func assertLength(t *testing.T, nodes []*html.Node, length int) {
+ if len(nodes) != length {
+ t.Errorf("Expected %d nodes, found %d.", length, len(nodes))
+ for i, n := range nodes {
+ t.Logf("Node %d: %+v.", i, n)
+ }
+ }
+}
+
+func assertClass(t *testing.T, sel *Selection, class string) {
+ if !sel.HasClass(class) {
+ t.Errorf("Expected node to have class %s, found %+v.", class, sel.Get(0))
+ }
+}
+
+func assertPanic(t *testing.T) {
+ if e := recover(); e == nil {
+ t.Error("Expected a panic.")
+ }
+}
+
+func assertEqual(t *testing.T, s1 *Selection, s2 *Selection) {
+ if s1 != s2 {
+ t.Error("Expected selection objects to be the same.")
+ }
+}
+
+func assertSelectionIs(t *testing.T, sel *Selection, is ...string) {
+ for i := 0; i < sel.Length(); i++ {
+ if !sel.Eq(i).Is(is[i]) {
+ t.Errorf("Expected node %d to be %s, found %+v", i, is[i], sel.Get(i))
+ }
+ }
+}
+
+func printSel(t *testing.T, sel *Selection) {
+ if testing.Verbose() {
+ h, err := sel.Html()
+ if err != nil {
+ t.Fatal(err)
+ }
+ t.Log(h)
+ }
+}
+
+func loadDoc(page string) *Document {
+ var f *os.File
+ var e error
+
+ if f, e = os.Open(fmt.Sprintf("./testdata/%s", page)); e != nil {
+ panic(e.Error())
+ }
+ defer f.Close()
+
+ var node *html.Node
+ if node, e = html.Parse(f); e != nil {
+ panic(e.Error())
+ }
+ return NewDocumentFromNode(node)
+}
+
+func TestNewDocument(t *testing.T) {
+ if f, e := os.Open("./testdata/page.html"); e != nil {
+ t.Error(e.Error())
+ } else {
+ defer f.Close()
+ if node, e := html.Parse(f); e != nil {
+ t.Error(e.Error())
+ } else {
+ doc = NewDocumentFromNode(node)
+ }
+ }
+}
+
+func TestNewDocumentFromReader(t *testing.T) {
+ cases := []struct {
+ src string
+ err bool
+ sel string
+ cnt int
+ }{
+ 0: {
+ src: `
+
+
+Test
+
+
Hi
+
+`,
+ sel: "h1",
+ cnt: 1,
+ },
+ 1: {
+ // Actually pretty hard to make html.Parse return an error
+ // based on content...
+ src: `>>qq>`,
+ },
+ }
+ buf := bytes.NewBuffer(nil)
+
+ for i, c := range cases {
+ buf.Reset()
+ buf.WriteString(c.src)
+
+ d, e := NewDocumentFromReader(buf)
+ if (e != nil) != c.err {
+ if c.err {
+ t.Errorf("[%d] - expected error, got none", i)
+ } else {
+ t.Errorf("[%d] - expected no error, got %s", i, e)
+ }
+ }
+ if c.sel != "" {
+ s := d.Find(c.sel)
+ if s.Length() != c.cnt {
+ t.Errorf("[%d] - expected %d nodes, found %d", i, c.cnt, s.Length())
+ }
+ }
+ }
+}
+
+func TestNewDocumentFromResponseNil(t *testing.T) {
+ _, e := NewDocumentFromResponse(nil)
+ if e == nil {
+ t.Error("Expected error, got none")
+ }
+}
+
+func TestIssue103(t *testing.T) {
+ d, err := NewDocumentFromReader(strings.NewReader("Scientists Stored These Images in DNA—Then Flawlessly Retrieved Them"))
+ if err != nil {
+ t.Error(err)
+ }
+ text := d.Find("title").Text()
+ for i, r := range text {
+ t.Logf("%d: %d - %q\n", i, r, string(r))
+ }
+ t.Log(text)
+}
diff --git a/vendor/github.com/PuerkitoBio/goquery/utilities.go b/vendor/github.com/PuerkitoBio/goquery/utilities.go
new file mode 100644
index 00000000..b4c061a4
--- /dev/null
+++ b/vendor/github.com/PuerkitoBio/goquery/utilities.go
@@ -0,0 +1,161 @@
+package goquery
+
+import (
+ "bytes"
+
+ "golang.org/x/net/html"
+)
+
+// used to determine if a set (map[*html.Node]bool) should be used
+// instead of iterating over a slice. The set uses more memory and
+// is slower than slice iteration for small N.
+const minNodesForSet = 1000
+
+var nodeNames = []string{
+ html.ErrorNode: "#error",
+ html.TextNode: "#text",
+ html.DocumentNode: "#document",
+ html.CommentNode: "#comment",
+}
+
+// NodeName returns the node name of the first element in the selection.
+// It tries to behave in a similar way as the DOM's nodeName property
+// (https://developer.mozilla.org/en-US/docs/Web/API/Node/nodeName).
+//
+// Go's net/html package defines the following node types, listed with
+// the corresponding returned value from this function:
+//
+// ErrorNode : #error
+// TextNode : #text
+// DocumentNode : #document
+// ElementNode : the element's tag name
+// CommentNode : #comment
+// DoctypeNode : the name of the document type
+//
+func NodeName(s *Selection) string {
+ if s.Length() == 0 {
+ return ""
+ }
+ switch n := s.Get(0); n.Type {
+ case html.ElementNode, html.DoctypeNode:
+ return n.Data
+ default:
+ if n.Type >= 0 && int(n.Type) < len(nodeNames) {
+ return nodeNames[n.Type]
+ }
+ return ""
+ }
+}
+
+// OuterHtml returns the outer HTML rendering of the first item in
+// the selection - that is, the HTML including the first element's
+// tag and attributes.
+//
+// Unlike InnerHtml, this is a function and not a method on the Selection,
+// because this is not a jQuery method (in javascript-land, this is
+// a property provided by the DOM).
+func OuterHtml(s *Selection) (string, error) {
+ var buf bytes.Buffer
+
+ if s.Length() == 0 {
+ return "", nil
+ }
+ n := s.Get(0)
+ if err := html.Render(&buf, n); err != nil {
+ return "", err
+ }
+ return buf.String(), nil
+}
+
+// Loop through all container nodes to search for the target node.
+func sliceContains(container []*html.Node, contained *html.Node) bool {
+ for _, n := range container {
+ if nodeContains(n, contained) {
+ return true
+ }
+ }
+
+ return false
+}
+
+// Checks if the contained node is within the container node.
+func nodeContains(container *html.Node, contained *html.Node) bool {
+ // Check if the parent of the contained node is the container node, traversing
+ // upward until the top is reached, or the container is found.
+ for contained = contained.Parent; contained != nil; contained = contained.Parent {
+ if container == contained {
+ return true
+ }
+ }
+ return false
+}
+
+// Checks if the target node is in the slice of nodes.
+func isInSlice(slice []*html.Node, node *html.Node) bool {
+ return indexInSlice(slice, node) > -1
+}
+
+// Returns the index of the target node in the slice, or -1.
+func indexInSlice(slice []*html.Node, node *html.Node) int {
+ if node != nil {
+ for i, n := range slice {
+ if n == node {
+ return i
+ }
+ }
+ }
+ return -1
+}
+
+// Appends the new nodes to the target slice, making sure no duplicate is added.
+// There is no check to the original state of the target slice, so it may still
+// contain duplicates. The target slice is returned because append() may create
+// a new underlying array. If targetSet is nil, a local set is created with the
+// target if len(target) + len(nodes) is greater than minNodesForSet.
+func appendWithoutDuplicates(target []*html.Node, nodes []*html.Node, targetSet map[*html.Node]bool) []*html.Node {
+ // if there are not that many nodes, don't use the map, faster to just use nested loops
+ // (unless a non-nil targetSet is passed, in which case the caller knows better).
+ if targetSet == nil && len(target)+len(nodes) < minNodesForSet {
+ for _, n := range nodes {
+ if !isInSlice(target, n) {
+ target = append(target, n)
+ }
+ }
+ return target
+ }
+
+ // if a targetSet is passed, then assume it is reliable, otherwise create one
+ // and initialize it with the current target contents.
+ if targetSet == nil {
+ targetSet = make(map[*html.Node]bool, len(target))
+ for _, n := range target {
+ targetSet[n] = true
+ }
+ }
+ for _, n := range nodes {
+ if !targetSet[n] {
+ target = append(target, n)
+ targetSet[n] = true
+ }
+ }
+
+ return target
+}
+
+// Loop through a selection, returning only those nodes that pass the predicate
+// function.
+func grep(sel *Selection, predicate func(i int, s *Selection) bool) (result []*html.Node) {
+ for i, n := range sel.Nodes {
+ if predicate(i, newSingleSelection(n, sel.document)) {
+ result = append(result, n)
+ }
+ }
+ return result
+}
+
+// Creates a new Selection object based on the specified nodes, and keeps the
+// source Selection object on the stack (linked list).
+func pushStack(fromSel *Selection, nodes []*html.Node) *Selection {
+ result := &Selection{nodes, fromSel.document, fromSel}
+ return result
+}
diff --git a/vendor/github.com/PuerkitoBio/goquery/utilities_test.go b/vendor/github.com/PuerkitoBio/goquery/utilities_test.go
new file mode 100644
index 00000000..c8e9d540
--- /dev/null
+++ b/vendor/github.com/PuerkitoBio/goquery/utilities_test.go
@@ -0,0 +1,128 @@
+package goquery
+
+import (
+ "reflect"
+ "sort"
+ "strings"
+ "testing"
+
+ "golang.org/x/net/html"
+)
+
+var allNodes = `
+
+
+
+
+
+
`},
+ {nComment, nil, ""},
+ {nText, nil, `
+ This is some text.
+ `},
+ {nil, sHeaders, ``},
+ }
+ for i, c := range cases {
+ if c.sel == nil {
+ c.sel = newSingleSelection(c.node, doc)
+ }
+ got, err := OuterHtml(c.sel)
+ if err != nil {
+ t.Fatal(err)
+ }
+
+ if got != c.want {
+ t.Errorf("%d: want %q, got %q", i, c.want, got)
+ }
+ }
+}
diff --git a/vendor/github.com/andybalholm/cascadia/.travis.yml b/vendor/github.com/andybalholm/cascadia/.travis.yml
new file mode 100644
index 00000000..6f227517
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/.travis.yml
@@ -0,0 +1,14 @@
+language: go
+
+go:
+ - 1.3
+ - 1.4
+
+install:
+ - go get github.com/andybalholm/cascadia
+
+script:
+ - go test -v
+
+notifications:
+ email: false
diff --git a/vendor/github.com/andybalholm/cascadia/LICENSE b/vendor/github.com/andybalholm/cascadia/LICENSE
new file mode 100755
index 00000000..ee5ad35a
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/LICENSE
@@ -0,0 +1,24 @@
+Copyright (c) 2011 Andy Balholm. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+ * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/vendor/github.com/andybalholm/cascadia/README.md b/vendor/github.com/andybalholm/cascadia/README.md
new file mode 100644
index 00000000..9021cb92
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/README.md
@@ -0,0 +1,7 @@
+# cascadia
+
+[![](https://travis-ci.org/andybalholm/cascadia.svg)](https://travis-ci.org/andybalholm/cascadia)
+
+The Cascadia package implements CSS selectors for use with the parse trees produced by the html package.
+
+To test CSS selectors without writing Go code, check out [cascadia](https://github.com/suntong/cascadia) the command line tool, a thin wrapper around this package.
diff --git a/vendor/github.com/andybalholm/cascadia/benchmark_test.go b/vendor/github.com/andybalholm/cascadia/benchmark_test.go
new file mode 100644
index 00000000..42bf5000
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/benchmark_test.go
@@ -0,0 +1,53 @@
+package cascadia
+
+import (
+ "strings"
+ "testing"
+
+ "golang.org/x/net/html"
+)
+
+func MustParseHTML(doc string) *html.Node {
+ dom, err := html.Parse(strings.NewReader(doc))
+ if err != nil {
+ panic(err)
+ }
+ return dom
+}
+
+var selector = MustCompile(`div.matched`)
+var doc = `
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+`
+var dom = MustParseHTML(doc)
+
+func BenchmarkMatchAll(b *testing.B) {
+ var matches []*html.Node
+ for i := 0; i < b.N; i++ {
+ matches = selector.MatchAll(dom)
+ }
+ _ = matches
+}
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test0 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test0
new file mode 100644
index 00000000..83a6561a
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test0
@@ -0,0 +1 @@
+address
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test1 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test1
new file mode 100644
index 00000000..f59ec20a
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test1
@@ -0,0 +1 @@
+*
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test10 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test10
new file mode 100644
index 00000000..0ee70eb0
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test10
@@ -0,0 +1 @@
+p[title]
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test11 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test11
new file mode 100644
index 00000000..66340c4a
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test11
@@ -0,0 +1 @@
+address[title="foo"]
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test12 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test12
new file mode 100644
index 00000000..6303f086
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test12
@@ -0,0 +1 @@
+[ title ~= foo ]
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test13 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test13
new file mode 100644
index 00000000..45d91eb6
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test13
@@ -0,0 +1 @@
+[title~="hello world"]
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test14 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test14
new file mode 100644
index 00000000..62e7d68a
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test14
@@ -0,0 +1 @@
+[lang|="en"]
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test15 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test15
new file mode 100644
index 00000000..fe9ab530
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test15
@@ -0,0 +1 @@
+[title^="foo"]
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test16 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test16
new file mode 100644
index 00000000..dbee7332
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test16
@@ -0,0 +1 @@
+[title$="bar"]
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test17 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test17
new file mode 100644
index 00000000..e4fb4032
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test17
@@ -0,0 +1 @@
+[title*="bar"]
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test18 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test18
new file mode 100644
index 00000000..60750143
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test18
@@ -0,0 +1 @@
+.t1:not(.t2)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test19 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test19
new file mode 100644
index 00000000..f04dfafd
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test19
@@ -0,0 +1 @@
+div:not(.t1)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test2 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test2
new file mode 100644
index 00000000..5529b9b4
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test2
@@ -0,0 +1 @@
+#foo
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test20 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test20
new file mode 100644
index 00000000..a1c88349
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test20
@@ -0,0 +1 @@
+li:nth-child(odd)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test21 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test21
new file mode 100644
index 00000000..b99fcb6a
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test21
@@ -0,0 +1 @@
+li:nth-child(even)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test22 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test22
new file mode 100644
index 00000000..a9ee2179
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test22
@@ -0,0 +1 @@
+li:nth-child(-n+2)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test23 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test23
new file mode 100644
index 00000000..aad519d5
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test23
@@ -0,0 +1 @@
+li:nth-child(3n+1)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test24 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test24
new file mode 100644
index 00000000..436a2191
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test24
@@ -0,0 +1 @@
+li:nth-last-child(odd)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test25 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test25
new file mode 100644
index 00000000..46f6cbc2
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test25
@@ -0,0 +1 @@
+li:nth-last-child(even)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test26 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test26
new file mode 100644
index 00000000..d18bf3b4
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test26
@@ -0,0 +1 @@
+li:nth-last-child(-n+2)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test27 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test27
new file mode 100644
index 00000000..d1d6eb31
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test27
@@ -0,0 +1 @@
+li:nth-last-child(3n+1)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test28 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test28
new file mode 100644
index 00000000..9a0c9493
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test28
@@ -0,0 +1 @@
+span:first-child
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test29 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test29
new file mode 100644
index 00000000..7058608e
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test29
@@ -0,0 +1 @@
+span:last-child
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test3 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test3
new file mode 100644
index 00000000..ee024825
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test3
@@ -0,0 +1 @@
+li#t1
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test30 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test30
new file mode 100644
index 00000000..536e6ffb
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test30
@@ -0,0 +1 @@
+p:nth-of-type(2)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test31 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test31
new file mode 100644
index 00000000..61c1fc75
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test31
@@ -0,0 +1 @@
+p:nth-last-of-type(2)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test32 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test32
new file mode 100644
index 00000000..d9a9dc54
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test32
@@ -0,0 +1 @@
+p:last-of-type
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test33 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test33
new file mode 100644
index 00000000..9052c419
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test33
@@ -0,0 +1 @@
+p:first-of-type
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test34 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test34
new file mode 100644
index 00000000..60bd1247
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test34
@@ -0,0 +1 @@
+p:only-child
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test35 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test35
new file mode 100644
index 00000000..87d9dbc6
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test35
@@ -0,0 +1 @@
+p:only-of-type
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test36 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test36
new file mode 100644
index 00000000..8e929542
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test36
@@ -0,0 +1 @@
+:empty
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test37 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test37
new file mode 100644
index 00000000..ba3455f5
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test37
@@ -0,0 +1 @@
+div p
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test38 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test38
new file mode 100644
index 00000000..d6f24c0a
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test38
@@ -0,0 +1 @@
+div table p
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test39 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test39
new file mode 100644
index 00000000..a72a605c
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test39
@@ -0,0 +1 @@
+div > p
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test4 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test4
new file mode 100644
index 00000000..7b253d3e
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test4
@@ -0,0 +1 @@
+*#t4
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test40 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test40
new file mode 100644
index 00000000..407ea3c4
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test40
@@ -0,0 +1 @@
+p ~ p
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test41 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test41
new file mode 100644
index 00000000..e36e0942
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test41
@@ -0,0 +1 @@
+p + p
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test42 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test42
new file mode 100644
index 00000000..fa59ada0
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test42
@@ -0,0 +1 @@
+li, p
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test43 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test43
new file mode 100644
index 00000000..e946ff3a
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test43
@@ -0,0 +1 @@
+p +/*This is a comment*/ p
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test44 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test44
new file mode 100644
index 00000000..df68954a
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test44
@@ -0,0 +1 @@
+p:contains("that wraps")
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test45 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test45
new file mode 100644
index 00000000..5c479a9a
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test45
@@ -0,0 +1 @@
+p:containsOwn("that wraps")
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test46 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test46
new file mode 100644
index 00000000..a189d03c
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test46
@@ -0,0 +1 @@
+:containsOwn("inner")
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test47 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test47
new file mode 100644
index 00000000..bfba3689
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test47
@@ -0,0 +1 @@
+p:containsOwn("block")
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test48 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test48
new file mode 100644
index 00000000..4a6abb3c
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test48
@@ -0,0 +1 @@
+div:has(#p1)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test49 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test49
new file mode 100644
index 00000000..2048a0cd
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test49
@@ -0,0 +1 @@
+div:has(:containsOwn("2"))
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test5 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test5
new file mode 100644
index 00000000..702c0f1e
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test5
@@ -0,0 +1 @@
+.t1
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test50 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test50
new file mode 100644
index 00000000..c062e4c1
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test50
@@ -0,0 +1 @@
+body :has(:containsOwn("2"))
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test51 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test51
new file mode 100644
index 00000000..15122604
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test51
@@ -0,0 +1 @@
+body :haschild(:containsOwn("2"))
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test52 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test52
new file mode 100644
index 00000000..c3dee62a
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test52
@@ -0,0 +1 @@
+p:matches([\d])
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test53 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test53
new file mode 100644
index 00000000..90f71d78
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test53
@@ -0,0 +1 @@
+p:matches([a-z])
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test54 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test54
new file mode 100644
index 00000000..88b4c283
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test54
@@ -0,0 +1 @@
+p:matches([a-zA-Z])
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test55 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test55
new file mode 100644
index 00000000..699b41ff
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test55
@@ -0,0 +1 @@
+p:matches([^\d])
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test56 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test56
new file mode 100644
index 00000000..83d4c474
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test56
@@ -0,0 +1 @@
+p:matches(^(0|a))
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test57 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test57
new file mode 100644
index 00000000..e8507ba6
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test57
@@ -0,0 +1 @@
+p:matches(^\d+$)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test58 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test58
new file mode 100644
index 00000000..e29dba9b
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test58
@@ -0,0 +1 @@
+p:not(:matches(^\d+$))
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test59 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test59
new file mode 100644
index 00000000..b5f72069
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test59
@@ -0,0 +1 @@
+div :matchesOwn(^\d+$)
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test6 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test6
new file mode 100644
index 00000000..cf58afcc
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test6
@@ -0,0 +1 @@
+p.t1
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test60 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test60
new file mode 100644
index 00000000..2154ba88
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test60
@@ -0,0 +1 @@
+[href#=(fina)]:not([href#=(\/\/[^\/]+untrusted)])
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test61 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test61
new file mode 100644
index 00000000..1c8f5258
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test61
@@ -0,0 +1 @@
+[href#=(^https:\/\/[^\/]*\/?news)]
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test7 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test7
new file mode 100644
index 00000000..9ad6c209
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test7
@@ -0,0 +1 @@
+div.teST
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test8 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test8
new file mode 100644
index 00000000..2ed12842
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test8
@@ -0,0 +1 @@
+.t1.fail
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test9 b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test9
new file mode 100644
index 00000000..8c1c2a27
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/corpus/test9
@@ -0,0 +1 @@
+p.t1.t2
\ No newline at end of file
diff --git a/vendor/github.com/andybalholm/cascadia/fuzz/fuzz.go b/vendor/github.com/andybalholm/cascadia/fuzz/fuzz.go
new file mode 100644
index 00000000..d1a46f8c
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/fuzz/fuzz.go
@@ -0,0 +1,15 @@
+package fuzz
+
+import "github.com/andybalholm/cascadia"
+
+// Fuzz is the entrypoint used by the go-fuzz framework
+func Fuzz(data []byte) int {
+ sel, err := cascadia.Compile(string(data))
+ if err != nil {
+ if sel != nil {
+ panic("sel != nil on error")
+ }
+ return 0
+ }
+ return 1
+}
diff --git a/vendor/github.com/andybalholm/cascadia/parser.go b/vendor/github.com/andybalholm/cascadia/parser.go
new file mode 100644
index 00000000..495db9cc
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/parser.go
@@ -0,0 +1,835 @@
+// Package cascadia is an implementation of CSS selectors.
+package cascadia
+
+import (
+ "errors"
+ "fmt"
+ "regexp"
+ "strconv"
+ "strings"
+
+ "golang.org/x/net/html"
+)
+
+// a parser for CSS selectors
+type parser struct {
+ s string // the source text
+ i int // the current position
+}
+
+// parseEscape parses a backslash escape.
+func (p *parser) parseEscape() (result string, err error) {
+ if len(p.s) < p.i+2 || p.s[p.i] != '\\' {
+ return "", errors.New("invalid escape sequence")
+ }
+
+ start := p.i + 1
+ c := p.s[start]
+ switch {
+ case c == '\r' || c == '\n' || c == '\f':
+ return "", errors.New("escaped line ending outside string")
+ case hexDigit(c):
+ // unicode escape (hex)
+ var i int
+ for i = start; i < p.i+6 && i < len(p.s) && hexDigit(p.s[i]); i++ {
+ // empty
+ }
+ v, _ := strconv.ParseUint(p.s[start:i], 16, 21)
+ if len(p.s) > i {
+ switch p.s[i] {
+ case '\r':
+ i++
+ if len(p.s) > i && p.s[i] == '\n' {
+ i++
+ }
+ case ' ', '\t', '\n', '\f':
+ i++
+ }
+ }
+ p.i = i
+ return string(rune(v)), nil
+ }
+
+ // Return the literal character after the backslash.
+ result = p.s[start : start+1]
+ p.i += 2
+ return result, nil
+}
+
+func hexDigit(c byte) bool {
+ return '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F'
+}
+
+// nameStart returns whether c can be the first character of an identifier
+// (not counting an initial hyphen, or an escape sequence).
+func nameStart(c byte) bool {
+ return 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || c == '_' || c > 127
+}
+
+// nameChar returns whether c can be a character within an identifier
+// (not counting an escape sequence).
+func nameChar(c byte) bool {
+ return 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || c == '_' || c > 127 ||
+ c == '-' || '0' <= c && c <= '9'
+}
+
+// parseIdentifier parses an identifier.
+func (p *parser) parseIdentifier() (result string, err error) {
+ startingDash := false
+ if len(p.s) > p.i && p.s[p.i] == '-' {
+ startingDash = true
+ p.i++
+ }
+
+ if len(p.s) <= p.i {
+ return "", errors.New("expected identifier, found EOF instead")
+ }
+
+ if c := p.s[p.i]; !(nameStart(c) || c == '\\') {
+ return "", fmt.Errorf("expected identifier, found %c instead", c)
+ }
+
+ result, err = p.parseName()
+ if startingDash && err == nil {
+ result = "-" + result
+ }
+ return
+}
+
+// parseName parses a name (which is like an identifier, but doesn't have
+// extra restrictions on the first character).
+func (p *parser) parseName() (result string, err error) {
+ i := p.i
+loop:
+ for i < len(p.s) {
+ c := p.s[i]
+ switch {
+ case nameChar(c):
+ start := i
+ for i < len(p.s) && nameChar(p.s[i]) {
+ i++
+ }
+ result += p.s[start:i]
+ case c == '\\':
+ p.i = i
+ val, err := p.parseEscape()
+ if err != nil {
+ return "", err
+ }
+ i = p.i
+ result += val
+ default:
+ break loop
+ }
+ }
+
+ if result == "" {
+ return "", errors.New("expected name, found EOF instead")
+ }
+
+ p.i = i
+ return result, nil
+}
+
+// parseString parses a single- or double-quoted string.
+func (p *parser) parseString() (result string, err error) {
+ i := p.i
+ if len(p.s) < i+2 {
+ return "", errors.New("expected string, found EOF instead")
+ }
+
+ quote := p.s[i]
+ i++
+
+loop:
+ for i < len(p.s) {
+ switch p.s[i] {
+ case '\\':
+ if len(p.s) > i+1 {
+ switch c := p.s[i+1]; c {
+ case '\r':
+ if len(p.s) > i+2 && p.s[i+2] == '\n' {
+ i += 3
+ continue loop
+ }
+ fallthrough
+ case '\n', '\f':
+ i += 2
+ continue loop
+ }
+ }
+ p.i = i
+ val, err := p.parseEscape()
+ if err != nil {
+ return "", err
+ }
+ i = p.i
+ result += val
+ case quote:
+ break loop
+ case '\r', '\n', '\f':
+ return "", errors.New("unexpected end of line in string")
+ default:
+ start := i
+ for i < len(p.s) {
+ if c := p.s[i]; c == quote || c == '\\' || c == '\r' || c == '\n' || c == '\f' {
+ break
+ }
+ i++
+ }
+ result += p.s[start:i]
+ }
+ }
+
+ if i >= len(p.s) {
+ return "", errors.New("EOF in string")
+ }
+
+ // Consume the final quote.
+ i++
+
+ p.i = i
+ return result, nil
+}
+
+// parseRegex parses a regular expression; the end is defined by encountering an
+// unmatched closing ')' or ']' which is not consumed
+func (p *parser) parseRegex() (rx *regexp.Regexp, err error) {
+ i := p.i
+ if len(p.s) < i+2 {
+ return nil, errors.New("expected regular expression, found EOF instead")
+ }
+
+ // number of open parens or brackets;
+ // when it becomes negative, finished parsing regex
+ open := 0
+
+loop:
+ for i < len(p.s) {
+ switch p.s[i] {
+ case '(', '[':
+ open++
+ case ')', ']':
+ open--
+ if open < 0 {
+ break loop
+ }
+ }
+ i++
+ }
+
+ if i >= len(p.s) {
+ return nil, errors.New("EOF in regular expression")
+ }
+ rx, err = regexp.Compile(p.s[p.i:i])
+ p.i = i
+ return rx, err
+}
+
+// skipWhitespace consumes whitespace characters and comments.
+// It returns true if there was actually anything to skip.
+func (p *parser) skipWhitespace() bool {
+ i := p.i
+ for i < len(p.s) {
+ switch p.s[i] {
+ case ' ', '\t', '\r', '\n', '\f':
+ i++
+ continue
+ case '/':
+ if strings.HasPrefix(p.s[i:], "/*") {
+ end := strings.Index(p.s[i+len("/*"):], "*/")
+ if end != -1 {
+ i += end + len("/**/")
+ continue
+ }
+ }
+ }
+ break
+ }
+
+ if i > p.i {
+ p.i = i
+ return true
+ }
+
+ return false
+}
+
+// consumeParenthesis consumes an opening parenthesis and any following
+// whitespace. It returns true if there was actually a parenthesis to skip.
+func (p *parser) consumeParenthesis() bool {
+ if p.i < len(p.s) && p.s[p.i] == '(' {
+ p.i++
+ p.skipWhitespace()
+ return true
+ }
+ return false
+}
+
+// consumeClosingParenthesis consumes a closing parenthesis and any preceding
+// whitespace. It returns true if there was actually a parenthesis to skip.
+func (p *parser) consumeClosingParenthesis() bool {
+ i := p.i
+ p.skipWhitespace()
+ if p.i < len(p.s) && p.s[p.i] == ')' {
+ p.i++
+ return true
+ }
+ p.i = i
+ return false
+}
+
+// parseTypeSelector parses a type selector (one that matches by tag name).
+func (p *parser) parseTypeSelector() (result Selector, err error) {
+ tag, err := p.parseIdentifier()
+ if err != nil {
+ return nil, err
+ }
+
+ return typeSelector(tag), nil
+}
+
+// parseIDSelector parses a selector that matches by id attribute.
+func (p *parser) parseIDSelector() (Selector, error) {
+ if p.i >= len(p.s) {
+ return nil, fmt.Errorf("expected id selector (#id), found EOF instead")
+ }
+ if p.s[p.i] != '#' {
+ return nil, fmt.Errorf("expected id selector (#id), found '%c' instead", p.s[p.i])
+ }
+
+ p.i++
+ id, err := p.parseName()
+ if err != nil {
+ return nil, err
+ }
+
+ return attributeEqualsSelector("id", id), nil
+}
+
+// parseClassSelector parses a selector that matches by class attribute.
+func (p *parser) parseClassSelector() (Selector, error) {
+ if p.i >= len(p.s) {
+ return nil, fmt.Errorf("expected class selector (.class), found EOF instead")
+ }
+ if p.s[p.i] != '.' {
+ return nil, fmt.Errorf("expected class selector (.class), found '%c' instead", p.s[p.i])
+ }
+
+ p.i++
+ class, err := p.parseIdentifier()
+ if err != nil {
+ return nil, err
+ }
+
+ return attributeIncludesSelector("class", class), nil
+}
+
+// parseAttributeSelector parses a selector that matches by attribute value.
+func (p *parser) parseAttributeSelector() (Selector, error) {
+ if p.i >= len(p.s) {
+ return nil, fmt.Errorf("expected attribute selector ([attribute]), found EOF instead")
+ }
+ if p.s[p.i] != '[' {
+ return nil, fmt.Errorf("expected attribute selector ([attribute]), found '%c' instead", p.s[p.i])
+ }
+
+ p.i++
+ p.skipWhitespace()
+ key, err := p.parseIdentifier()
+ if err != nil {
+ return nil, err
+ }
+
+ p.skipWhitespace()
+ if p.i >= len(p.s) {
+ return nil, errors.New("unexpected EOF in attribute selector")
+ }
+
+ if p.s[p.i] == ']' {
+ p.i++
+ return attributeExistsSelector(key), nil
+ }
+
+ if p.i+2 >= len(p.s) {
+ return nil, errors.New("unexpected EOF in attribute selector")
+ }
+
+ op := p.s[p.i : p.i+2]
+ if op[0] == '=' {
+ op = "="
+ } else if op[1] != '=' {
+ return nil, fmt.Errorf(`expected equality operator, found "%s" instead`, op)
+ }
+ p.i += len(op)
+
+ p.skipWhitespace()
+ if p.i >= len(p.s) {
+ return nil, errors.New("unexpected EOF in attribute selector")
+ }
+ var val string
+ var rx *regexp.Regexp
+ if op == "#=" {
+ rx, err = p.parseRegex()
+ } else {
+ switch p.s[p.i] {
+ case '\'', '"':
+ val, err = p.parseString()
+ default:
+ val, err = p.parseIdentifier()
+ }
+ }
+ if err != nil {
+ return nil, err
+ }
+
+ p.skipWhitespace()
+ if p.i >= len(p.s) {
+ return nil, errors.New("unexpected EOF in attribute selector")
+ }
+ if p.s[p.i] != ']' {
+ return nil, fmt.Errorf("expected ']', found '%c' instead", p.s[p.i])
+ }
+ p.i++
+
+ switch op {
+ case "=":
+ return attributeEqualsSelector(key, val), nil
+ case "!=":
+ return attributeNotEqualSelector(key, val), nil
+ case "~=":
+ return attributeIncludesSelector(key, val), nil
+ case "|=":
+ return attributeDashmatchSelector(key, val), nil
+ case "^=":
+ return attributePrefixSelector(key, val), nil
+ case "$=":
+ return attributeSuffixSelector(key, val), nil
+ case "*=":
+ return attributeSubstringSelector(key, val), nil
+ case "#=":
+ return attributeRegexSelector(key, rx), nil
+ }
+
+ return nil, fmt.Errorf("attribute operator %q is not supported", op)
+}
+
+var errExpectedParenthesis = errors.New("expected '(' but didn't find it")
+var errExpectedClosingParenthesis = errors.New("expected ')' but didn't find it")
+var errUnmatchedParenthesis = errors.New("unmatched '('")
+
+// parsePseudoclassSelector parses a pseudoclass selector like :not(p).
+func (p *parser) parsePseudoclassSelector() (Selector, error) {
+ if p.i >= len(p.s) {
+ return nil, fmt.Errorf("expected pseudoclass selector (:pseudoclass), found EOF instead")
+ }
+ if p.s[p.i] != ':' {
+ return nil, fmt.Errorf("expected attribute selector (:pseudoclass), found '%c' instead", p.s[p.i])
+ }
+
+ p.i++
+ name, err := p.parseIdentifier()
+ if err != nil {
+ return nil, err
+ }
+ name = toLowerASCII(name)
+
+ switch name {
+ case "not", "has", "haschild":
+ if !p.consumeParenthesis() {
+ return nil, errExpectedParenthesis
+ }
+ sel, parseErr := p.parseSelectorGroup()
+ if parseErr != nil {
+ return nil, parseErr
+ }
+ if !p.consumeClosingParenthesis() {
+ return nil, errExpectedClosingParenthesis
+ }
+
+ switch name {
+ case "not":
+ return negatedSelector(sel), nil
+ case "has":
+ return hasDescendantSelector(sel), nil
+ case "haschild":
+ return hasChildSelector(sel), nil
+ }
+
+ case "contains", "containsown":
+ if !p.consumeParenthesis() {
+ return nil, errExpectedParenthesis
+ }
+ if p.i == len(p.s) {
+ return nil, errUnmatchedParenthesis
+ }
+ var val string
+ switch p.s[p.i] {
+ case '\'', '"':
+ val, err = p.parseString()
+ default:
+ val, err = p.parseIdentifier()
+ }
+ if err != nil {
+ return nil, err
+ }
+ val = strings.ToLower(val)
+ p.skipWhitespace()
+ if p.i >= len(p.s) {
+ return nil, errors.New("unexpected EOF in pseudo selector")
+ }
+ if !p.consumeClosingParenthesis() {
+ return nil, errExpectedClosingParenthesis
+ }
+
+ switch name {
+ case "contains":
+ return textSubstrSelector(val), nil
+ case "containsown":
+ return ownTextSubstrSelector(val), nil
+ }
+
+ case "matches", "matchesown":
+ if !p.consumeParenthesis() {
+ return nil, errExpectedParenthesis
+ }
+ rx, err := p.parseRegex()
+ if err != nil {
+ return nil, err
+ }
+ if p.i >= len(p.s) {
+ return nil, errors.New("unexpected EOF in pseudo selector")
+ }
+ if !p.consumeClosingParenthesis() {
+ return nil, errExpectedClosingParenthesis
+ }
+
+ switch name {
+ case "matches":
+ return textRegexSelector(rx), nil
+ case "matchesown":
+ return ownTextRegexSelector(rx), nil
+ }
+
+ case "nth-child", "nth-last-child", "nth-of-type", "nth-last-of-type":
+ if !p.consumeParenthesis() {
+ return nil, errExpectedParenthesis
+ }
+ a, b, err := p.parseNth()
+ if err != nil {
+ return nil, err
+ }
+ if !p.consumeClosingParenthesis() {
+ return nil, errExpectedClosingParenthesis
+ }
+ if a == 0 {
+ switch name {
+ case "nth-child":
+ return simpleNthChildSelector(b, false), nil
+ case "nth-of-type":
+ return simpleNthChildSelector(b, true), nil
+ case "nth-last-child":
+ return simpleNthLastChildSelector(b, false), nil
+ case "nth-last-of-type":
+ return simpleNthLastChildSelector(b, true), nil
+ }
+ }
+ return nthChildSelector(a, b,
+ name == "nth-last-child" || name == "nth-last-of-type",
+ name == "nth-of-type" || name == "nth-last-of-type"),
+ nil
+
+ case "first-child":
+ return simpleNthChildSelector(1, false), nil
+ case "last-child":
+ return simpleNthLastChildSelector(1, false), nil
+ case "first-of-type":
+ return simpleNthChildSelector(1, true), nil
+ case "last-of-type":
+ return simpleNthLastChildSelector(1, true), nil
+ case "only-child":
+ return onlyChildSelector(false), nil
+ case "only-of-type":
+ return onlyChildSelector(true), nil
+ case "input":
+ return inputSelector, nil
+ case "empty":
+ return emptyElementSelector, nil
+ case "root":
+ return rootSelector, nil
+ }
+
+ return nil, fmt.Errorf("unknown pseudoclass :%s", name)
+}
+
+// parseInteger parses a decimal integer.
+func (p *parser) parseInteger() (int, error) {
+ i := p.i
+ start := i
+ for i < len(p.s) && '0' <= p.s[i] && p.s[i] <= '9' {
+ i++
+ }
+ if i == start {
+ return 0, errors.New("expected integer, but didn't find it")
+ }
+ p.i = i
+
+ val, err := strconv.Atoi(p.s[start:i])
+ if err != nil {
+ return 0, err
+ }
+
+ return val, nil
+}
+
+// parseNth parses the argument for :nth-child (normally of the form an+b).
+func (p *parser) parseNth() (a, b int, err error) {
+ // initial state
+ if p.i >= len(p.s) {
+ goto eof
+ }
+ switch p.s[p.i] {
+ case '-':
+ p.i++
+ goto negativeA
+ case '+':
+ p.i++
+ goto positiveA
+ case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+ goto positiveA
+ case 'n', 'N':
+ a = 1
+ p.i++
+ goto readN
+ case 'o', 'O', 'e', 'E':
+ id, nameErr := p.parseName()
+ if nameErr != nil {
+ return 0, 0, nameErr
+ }
+ id = toLowerASCII(id)
+ if id == "odd" {
+ return 2, 1, nil
+ }
+ if id == "even" {
+ return 2, 0, nil
+ }
+ return 0, 0, fmt.Errorf("expected 'odd' or 'even', but found '%s' instead", id)
+ default:
+ goto invalid
+ }
+
+positiveA:
+ if p.i >= len(p.s) {
+ goto eof
+ }
+ switch p.s[p.i] {
+ case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+ a, err = p.parseInteger()
+ if err != nil {
+ return 0, 0, err
+ }
+ goto readA
+ case 'n', 'N':
+ a = 1
+ p.i++
+ goto readN
+ default:
+ goto invalid
+ }
+
+negativeA:
+ if p.i >= len(p.s) {
+ goto eof
+ }
+ switch p.s[p.i] {
+ case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+ a, err = p.parseInteger()
+ if err != nil {
+ return 0, 0, err
+ }
+ a = -a
+ goto readA
+ case 'n', 'N':
+ a = -1
+ p.i++
+ goto readN
+ default:
+ goto invalid
+ }
+
+readA:
+ if p.i >= len(p.s) {
+ goto eof
+ }
+ switch p.s[p.i] {
+ case 'n', 'N':
+ p.i++
+ goto readN
+ default:
+ // The number we read as a is actually b.
+ return 0, a, nil
+ }
+
+readN:
+ p.skipWhitespace()
+ if p.i >= len(p.s) {
+ goto eof
+ }
+ switch p.s[p.i] {
+ case '+':
+ p.i++
+ p.skipWhitespace()
+ b, err = p.parseInteger()
+ if err != nil {
+ return 0, 0, err
+ }
+ return a, b, nil
+ case '-':
+ p.i++
+ p.skipWhitespace()
+ b, err = p.parseInteger()
+ if err != nil {
+ return 0, 0, err
+ }
+ return a, -b, nil
+ default:
+ return a, 0, nil
+ }
+
+eof:
+ return 0, 0, errors.New("unexpected EOF while attempting to parse expression of form an+b")
+
+invalid:
+ return 0, 0, errors.New("unexpected character while attempting to parse expression of form an+b")
+}
+
+// parseSimpleSelectorSequence parses a selector sequence that applies to
+// a single element.
+func (p *parser) parseSimpleSelectorSequence() (Selector, error) {
+ var result Selector
+
+ if p.i >= len(p.s) {
+ return nil, errors.New("expected selector, found EOF instead")
+ }
+
+ switch p.s[p.i] {
+ case '*':
+ // It's the universal selector. Just skip over it, since it doesn't affect the meaning.
+ p.i++
+ case '#', '.', '[', ':':
+ // There's no type selector. Wait to process the other till the main loop.
+ default:
+ r, err := p.parseTypeSelector()
+ if err != nil {
+ return nil, err
+ }
+ result = r
+ }
+
+loop:
+ for p.i < len(p.s) {
+ var ns Selector
+ var err error
+ switch p.s[p.i] {
+ case '#':
+ ns, err = p.parseIDSelector()
+ case '.':
+ ns, err = p.parseClassSelector()
+ case '[':
+ ns, err = p.parseAttributeSelector()
+ case ':':
+ ns, err = p.parsePseudoclassSelector()
+ default:
+ break loop
+ }
+ if err != nil {
+ return nil, err
+ }
+ if result == nil {
+ result = ns
+ } else {
+ result = intersectionSelector(result, ns)
+ }
+ }
+
+ if result == nil {
+ result = func(n *html.Node) bool {
+ return n.Type == html.ElementNode
+ }
+ }
+
+ return result, nil
+}
+
+// parseSelector parses a selector that may include combinators.
+func (p *parser) parseSelector() (result Selector, err error) {
+ p.skipWhitespace()
+ result, err = p.parseSimpleSelectorSequence()
+ if err != nil {
+ return
+ }
+
+ for {
+ var combinator byte
+ if p.skipWhitespace() {
+ combinator = ' '
+ }
+ if p.i >= len(p.s) {
+ return
+ }
+
+ switch p.s[p.i] {
+ case '+', '>', '~':
+ combinator = p.s[p.i]
+ p.i++
+ p.skipWhitespace()
+ case ',', ')':
+ // These characters can't begin a selector, but they can legally occur after one.
+ return
+ }
+
+ if combinator == 0 {
+ return
+ }
+
+ c, err := p.parseSimpleSelectorSequence()
+ if err != nil {
+ return nil, err
+ }
+
+ switch combinator {
+ case ' ':
+ result = descendantSelector(result, c)
+ case '>':
+ result = childSelector(result, c)
+ case '+':
+ result = siblingSelector(result, c, true)
+ case '~':
+ result = siblingSelector(result, c, false)
+ }
+ }
+
+ panic("unreachable")
+}
+
+// parseSelectorGroup parses a group of selectors, separated by commas.
+func (p *parser) parseSelectorGroup() (result Selector, err error) {
+ result, err = p.parseSelector()
+ if err != nil {
+ return
+ }
+
+ for p.i < len(p.s) {
+ if p.s[p.i] != ',' {
+ return result, nil
+ }
+ p.i++
+ c, err := p.parseSelector()
+ if err != nil {
+ return nil, err
+ }
+ result = unionSelector(result, c)
+ }
+
+ return
+}
diff --git a/vendor/github.com/andybalholm/cascadia/parser_test.go b/vendor/github.com/andybalholm/cascadia/parser_test.go
new file mode 100644
index 00000000..47dd4a69
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/parser_test.go
@@ -0,0 +1,86 @@
+package cascadia
+
+import (
+ "testing"
+)
+
+var identifierTests = map[string]string{
+ "x": "x",
+ "96": "",
+ "-x": "-x",
+ `r\e9 sumé`: "résumé",
+ `a\"b`: `a"b`,
+}
+
+func TestParseIdentifier(t *testing.T) {
+ for source, want := range identifierTests {
+ p := &parser{s: source}
+ got, err := p.parseIdentifier()
+
+ if err != nil {
+ if want == "" {
+ // It was supposed to be an error.
+ continue
+ }
+ t.Errorf("parsing %q: got error (%s), want %q", source, err, want)
+ continue
+ }
+
+ if want == "" {
+ if err == nil {
+ t.Errorf("parsing %q: got %q, want error", source, got)
+ }
+ continue
+ }
+
+ if p.i < len(source) {
+ t.Errorf("parsing %q: %d bytes left over", source, len(source)-p.i)
+ continue
+ }
+
+ if got != want {
+ t.Errorf("parsing %q: got %q, want %q", source, got, want)
+ }
+ }
+}
+
+var stringTests = map[string]string{
+ `"x"`: "x",
+ `'x'`: "x",
+ `'x`: "",
+ "'x\\\r\nx'": "xx",
+ `"r\e9 sumé"`: "résumé",
+ `"a\"b"`: `a"b`,
+}
+
+func TestParseString(t *testing.T) {
+ for source, want := range stringTests {
+ p := &parser{s: source}
+ got, err := p.parseString()
+
+ if err != nil {
+ if want == "" {
+ // It was supposed to be an error.
+ continue
+ }
+ t.Errorf("parsing %q: got error (%s), want %q", source, err, want)
+ continue
+ }
+
+ if want == "" {
+ if err == nil {
+ t.Errorf("parsing %q: got %q, want error", source, got)
+ }
+ continue
+ }
+
+ if p.i < len(source) {
+ t.Errorf("parsing %q: %d bytes left over", source, len(source)-p.i)
+ continue
+ }
+
+ if got != want {
+ t.Errorf("parsing %q: got %q, want %q", source, got, want)
+ }
+ }
+}
diff --git a/vendor/github.com/andybalholm/cascadia/selector.go b/vendor/github.com/andybalholm/cascadia/selector.go
new file mode 100644
index 00000000..9fb05ccb
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/selector.go
@@ -0,0 +1,622 @@
+package cascadia
+
+import (
+ "bytes"
+ "fmt"
+ "regexp"
+ "strings"
+
+ "golang.org/x/net/html"
+)
+
+// the Selector type, and functions for creating them
+
+// A Selector is a function which tells whether a node matches or not.
+type Selector func(*html.Node) bool
+
+// hasChildMatch returns whether n has any child that matches a.
+func hasChildMatch(n *html.Node, a Selector) bool {
+ for c := n.FirstChild; c != nil; c = c.NextSibling {
+ if a(c) {
+ return true
+ }
+ }
+ return false
+}
+
+// hasDescendantMatch performs a depth-first search of n's descendants,
+// testing whether any of them match a. It returns true as soon as a match is
+// found, or false if no match is found.
+func hasDescendantMatch(n *html.Node, a Selector) bool {
+ for c := n.FirstChild; c != nil; c = c.NextSibling {
+ if a(c) || (c.Type == html.ElementNode && hasDescendantMatch(c, a)) {
+ return true
+ }
+ }
+ return false
+}
+
+// Compile parses a selector and returns, if successful, a Selector object
+// that can be used to match against html.Node objects.
+func Compile(sel string) (Selector, error) {
+ p := &parser{s: sel}
+ compiled, err := p.parseSelectorGroup()
+ if err != nil {
+ return nil, err
+ }
+
+ if p.i < len(sel) {
+ return nil, fmt.Errorf("parsing %q: %d bytes left over", sel, len(sel)-p.i)
+ }
+
+ return compiled, nil
+}
+
+// MustCompile is like Compile, but panics instead of returning an error.
+func MustCompile(sel string) Selector {
+ compiled, err := Compile(sel)
+ if err != nil {
+ panic(err)
+ }
+ return compiled
+}
+
+// MatchAll returns a slice of the nodes that match the selector,
+// from n and its children.
+func (s Selector) MatchAll(n *html.Node) []*html.Node {
+ return s.matchAllInto(n, nil)
+}
+
+func (s Selector) matchAllInto(n *html.Node, storage []*html.Node) []*html.Node {
+ if s(n) {
+ storage = append(storage, n)
+ }
+
+ for child := n.FirstChild; child != nil; child = child.NextSibling {
+ storage = s.matchAllInto(child, storage)
+ }
+
+ return storage
+}
+
+// Match returns true if the node matches the selector.
+func (s Selector) Match(n *html.Node) bool {
+ return s(n)
+}
+
+// MatchFirst returns the first node that matches s, from n and its children.
+func (s Selector) MatchFirst(n *html.Node) *html.Node {
+ if s.Match(n) {
+ return n
+ }
+
+ for c := n.FirstChild; c != nil; c = c.NextSibling {
+ m := s.MatchFirst(c)
+ if m != nil {
+ return m
+ }
+ }
+ return nil
+}
+
+// Filter returns the nodes in nodes that match the selector.
+func (s Selector) Filter(nodes []*html.Node) (result []*html.Node) {
+ for _, n := range nodes {
+ if s(n) {
+ result = append(result, n)
+ }
+ }
+ return result
+}
+
+// typeSelector returns a Selector that matches elements with a given tag name.
+func typeSelector(tag string) Selector {
+ tag = toLowerASCII(tag)
+ return func(n *html.Node) bool {
+ return n.Type == html.ElementNode && n.Data == tag
+ }
+}
+
+// toLowerASCII returns s with all ASCII capital letters lowercased.
+func toLowerASCII(s string) string {
+ var b []byte
+ for i := 0; i < len(s); i++ {
+ if c := s[i]; 'A' <= c && c <= 'Z' {
+ if b == nil {
+ b = make([]byte, len(s))
+ copy(b, s)
+ }
+ b[i] = s[i] + ('a' - 'A')
+ }
+ }
+
+ if b == nil {
+ return s
+ }
+
+ return string(b)
+}
+
+// attributeSelector returns a Selector that matches elements
+// where the attribute named key satisifes the function f.
+func attributeSelector(key string, f func(string) bool) Selector {
+ key = toLowerASCII(key)
+ return func(n *html.Node) bool {
+ if n.Type != html.ElementNode {
+ return false
+ }
+ for _, a := range n.Attr {
+ if a.Key == key && f(a.Val) {
+ return true
+ }
+ }
+ return false
+ }
+}
+
+// attributeExistsSelector returns a Selector that matches elements that have
+// an attribute named key.
+func attributeExistsSelector(key string) Selector {
+ return attributeSelector(key, func(string) bool { return true })
+}
+
+// attributeEqualsSelector returns a Selector that matches elements where
+// the attribute named key has the value val.
+func attributeEqualsSelector(key, val string) Selector {
+ return attributeSelector(key,
+ func(s string) bool {
+ return s == val
+ })
+}
+
+// attributeNotEqualSelector returns a Selector that matches elements where
+// the attribute named key does not have the value val.
+func attributeNotEqualSelector(key, val string) Selector {
+ key = toLowerASCII(key)
+ return func(n *html.Node) bool {
+ if n.Type != html.ElementNode {
+ return false
+ }
+ for _, a := range n.Attr {
+ if a.Key == key && a.Val == val {
+ return false
+ }
+ }
+ return true
+ }
+}
+
+// attributeIncludesSelector returns a Selector that matches elements where
+// the attribute named key is a whitespace-separated list that includes val.
+func attributeIncludesSelector(key, val string) Selector {
+ return attributeSelector(key,
+ func(s string) bool {
+ for s != "" {
+ i := strings.IndexAny(s, " \t\r\n\f")
+ if i == -1 {
+ return s == val
+ }
+ if s[:i] == val {
+ return true
+ }
+ s = s[i+1:]
+ }
+ return false
+ })
+}
+
+// attributeDashmatchSelector returns a Selector that matches elements where
+// the attribute named key equals val or starts with val plus a hyphen.
+func attributeDashmatchSelector(key, val string) Selector {
+ return attributeSelector(key,
+ func(s string) bool {
+ if s == val {
+ return true
+ }
+ if len(s) <= len(val) {
+ return false
+ }
+ if s[:len(val)] == val && s[len(val)] == '-' {
+ return true
+ }
+ return false
+ })
+}
+
+// attributePrefixSelector returns a Selector that matches elements where
+// the attribute named key starts with val.
+func attributePrefixSelector(key, val string) Selector {
+ return attributeSelector(key,
+ func(s string) bool {
+ if strings.TrimSpace(s) == "" {
+ return false
+ }
+ return strings.HasPrefix(s, val)
+ })
+}
+
+// attributeSuffixSelector returns a Selector that matches elements where
+// the attribute named key ends with val.
+func attributeSuffixSelector(key, val string) Selector {
+ return attributeSelector(key,
+ func(s string) bool {
+ if strings.TrimSpace(s) == "" {
+ return false
+ }
+ return strings.HasSuffix(s, val)
+ })
+}
+
+// attributeSubstringSelector returns a Selector that matches nodes where
+// the attribute named key contains val.
+func attributeSubstringSelector(key, val string) Selector {
+ return attributeSelector(key,
+ func(s string) bool {
+ if strings.TrimSpace(s) == "" {
+ return false
+ }
+ return strings.Contains(s, val)
+ })
+}
+
+// attributeRegexSelector returns a Selector that matches nodes where
+// the attribute named key matches the regular expression rx
+func attributeRegexSelector(key string, rx *regexp.Regexp) Selector {
+ return attributeSelector(key,
+ func(s string) bool {
+ return rx.MatchString(s)
+ })
+}
+
+// intersectionSelector returns a selector that matches nodes that match
+// both a and b.
+func intersectionSelector(a, b Selector) Selector {
+ return func(n *html.Node) bool {
+ return a(n) && b(n)
+ }
+}
+
+// unionSelector returns a selector that matches elements that match
+// either a or b.
+func unionSelector(a, b Selector) Selector {
+ return func(n *html.Node) bool {
+ return a(n) || b(n)
+ }
+}
+
+// negatedSelector returns a selector that matches elements that do not match a.
+func negatedSelector(a Selector) Selector {
+ return func(n *html.Node) bool {
+ if n.Type != html.ElementNode {
+ return false
+ }
+ return !a(n)
+ }
+}
+
+// writeNodeText writes the text contained in n and its descendants to b.
+func writeNodeText(n *html.Node, b *bytes.Buffer) {
+ switch n.Type {
+ case html.TextNode:
+ b.WriteString(n.Data)
+ case html.ElementNode:
+ for c := n.FirstChild; c != nil; c = c.NextSibling {
+ writeNodeText(c, b)
+ }
+ }
+}
+
+// nodeText returns the text contained in n and its descendants.
+func nodeText(n *html.Node) string {
+ var b bytes.Buffer
+ writeNodeText(n, &b)
+ return b.String()
+}
+
+// nodeOwnText returns the contents of the text nodes that are direct
+// children of n.
+func nodeOwnText(n *html.Node) string {
+ var b bytes.Buffer
+ for c := n.FirstChild; c != nil; c = c.NextSibling {
+ if c.Type == html.TextNode {
+ b.WriteString(c.Data)
+ }
+ }
+ return b.String()
+}
+
+// textSubstrSelector returns a selector that matches nodes that
+// contain the given text.
+func textSubstrSelector(val string) Selector {
+ return func(n *html.Node) bool {
+ text := strings.ToLower(nodeText(n))
+ return strings.Contains(text, val)
+ }
+}
+
+// ownTextSubstrSelector returns a selector that matches nodes that
+// directly contain the given text
+func ownTextSubstrSelector(val string) Selector {
+ return func(n *html.Node) bool {
+ text := strings.ToLower(nodeOwnText(n))
+ return strings.Contains(text, val)
+ }
+}
+
+// textRegexSelector returns a selector that matches nodes whose text matches
+// the specified regular expression
+func textRegexSelector(rx *regexp.Regexp) Selector {
+ return func(n *html.Node) bool {
+ return rx.MatchString(nodeText(n))
+ }
+}
+
+// ownTextRegexSelector returns a selector that matches nodes whose text
+// directly matches the specified regular expression
+func ownTextRegexSelector(rx *regexp.Regexp) Selector {
+ return func(n *html.Node) bool {
+ return rx.MatchString(nodeOwnText(n))
+ }
+}
+
+// hasChildSelector returns a selector that matches elements
+// with a child that matches a.
+func hasChildSelector(a Selector) Selector {
+ return func(n *html.Node) bool {
+ if n.Type != html.ElementNode {
+ return false
+ }
+ return hasChildMatch(n, a)
+ }
+}
+
+// hasDescendantSelector returns a selector that matches elements
+// with any descendant that matches a.
+func hasDescendantSelector(a Selector) Selector {
+ return func(n *html.Node) bool {
+ if n.Type != html.ElementNode {
+ return false
+ }
+ return hasDescendantMatch(n, a)
+ }
+}
+
+// nthChildSelector returns a selector that implements :nth-child(an+b).
+// If last is true, implements :nth-last-child instead.
+// If ofType is true, implements :nth-of-type instead.
+func nthChildSelector(a, b int, last, ofType bool) Selector {
+ return func(n *html.Node) bool {
+ if n.Type != html.ElementNode {
+ return false
+ }
+
+ parent := n.Parent
+ if parent == nil {
+ return false
+ }
+
+ if parent.Type == html.DocumentNode {
+ return false
+ }
+
+ i := -1
+ count := 0
+ for c := parent.FirstChild; c != nil; c = c.NextSibling {
+ if (c.Type != html.ElementNode) || (ofType && c.Data != n.Data) {
+ continue
+ }
+ count++
+ if c == n {
+ i = count
+ if !last {
+ break
+ }
+ }
+ }
+
+ if i == -1 {
+ // This shouldn't happen, since n should always be one of its parent's children.
+ return false
+ }
+
+ if last {
+ i = count - i + 1
+ }
+
+ i -= b
+ if a == 0 {
+ return i == 0
+ }
+
+ return i%a == 0 && i/a >= 0
+ }
+}
+
+// simpleNthChildSelector returns a selector that implements :nth-child(b).
+// If ofType is true, implements :nth-of-type instead.
+func simpleNthChildSelector(b int, ofType bool) Selector {
+ return func(n *html.Node) bool {
+ if n.Type != html.ElementNode {
+ return false
+ }
+
+ parent := n.Parent
+ if parent == nil {
+ return false
+ }
+
+ if parent.Type == html.DocumentNode {
+ return false
+ }
+
+ count := 0
+ for c := parent.FirstChild; c != nil; c = c.NextSibling {
+ if c.Type != html.ElementNode || (ofType && c.Data != n.Data) {
+ continue
+ }
+ count++
+ if c == n {
+ return count == b
+ }
+ if count >= b {
+ return false
+ }
+ }
+ return false
+ }
+}
+
+// simpleNthLastChildSelector returns a selector that implements
+// :nth-last-child(b). If ofType is true, implements :nth-last-of-type
+// instead.
+func simpleNthLastChildSelector(b int, ofType bool) Selector {
+ return func(n *html.Node) bool {
+ if n.Type != html.ElementNode {
+ return false
+ }
+
+ parent := n.Parent
+ if parent == nil {
+ return false
+ }
+
+ if parent.Type == html.DocumentNode {
+ return false
+ }
+
+ count := 0
+ for c := parent.LastChild; c != nil; c = c.PrevSibling {
+ if c.Type != html.ElementNode || (ofType && c.Data != n.Data) {
+ continue
+ }
+ count++
+ if c == n {
+ return count == b
+ }
+ if count >= b {
+ return false
+ }
+ }
+ return false
+ }
+}
+
+// onlyChildSelector returns a selector that implements :only-child.
+// If ofType is true, it implements :only-of-type instead.
+func onlyChildSelector(ofType bool) Selector {
+ return func(n *html.Node) bool {
+ if n.Type != html.ElementNode {
+ return false
+ }
+
+ parent := n.Parent
+ if parent == nil {
+ return false
+ }
+
+ if parent.Type == html.DocumentNode {
+ return false
+ }
+
+ count := 0
+ for c := parent.FirstChild; c != nil; c = c.NextSibling {
+ if (c.Type != html.ElementNode) || (ofType && c.Data != n.Data) {
+ continue
+ }
+ count++
+ if count > 1 {
+ return false
+ }
+ }
+
+ return count == 1
+ }
+}
+
+// inputSelector is a Selector that matches input, select, textarea and button elements.
+func inputSelector(n *html.Node) bool {
+ return n.Type == html.ElementNode && (n.Data == "input" || n.Data == "select" || n.Data == "textarea" || n.Data == "button")
+}
+
+// emptyElementSelector is a Selector that matches empty elements.
+func emptyElementSelector(n *html.Node) bool {
+ if n.Type != html.ElementNode {
+ return false
+ }
+
+ for c := n.FirstChild; c != nil; c = c.NextSibling {
+ switch c.Type {
+ case html.ElementNode, html.TextNode:
+ return false
+ }
+ }
+
+ return true
+}
+
+// descendantSelector returns a Selector that matches an element if
+// it matches d and has an ancestor that matches a.
+func descendantSelector(a, d Selector) Selector {
+ return func(n *html.Node) bool {
+ if !d(n) {
+ return false
+ }
+
+ for p := n.Parent; p != nil; p = p.Parent {
+ if a(p) {
+ return true
+ }
+ }
+
+ return false
+ }
+}
+
+// childSelector returns a Selector that matches an element if
+// it matches d and its parent matches a.
+func childSelector(a, d Selector) Selector {
+ return func(n *html.Node) bool {
+ return d(n) && n.Parent != nil && a(n.Parent)
+ }
+}
+
+// siblingSelector returns a Selector that matches an element
+// if it matches s2 and in is preceded by an element that matches s1.
+// If adjacent is true, the sibling must be immediately before the element.
+func siblingSelector(s1, s2 Selector, adjacent bool) Selector {
+ return func(n *html.Node) bool {
+ if !s2(n) {
+ return false
+ }
+
+ if adjacent {
+ for n = n.PrevSibling; n != nil; n = n.PrevSibling {
+ if n.Type == html.TextNode || n.Type == html.CommentNode {
+ continue
+ }
+ return s1(n)
+ }
+ return false
+ }
+
+ // Walk backwards looking for element that matches s1
+ for c := n.PrevSibling; c != nil; c = c.PrevSibling {
+ if s1(c) {
+ return true
+ }
+ }
+
+ return false
+ }
+}
+
+// rootSelector implements :root
+func rootSelector(n *html.Node) bool {
+ if n.Type != html.ElementNode {
+ return false
+ }
+ if n.Parent == nil {
+ return false
+ }
+ return n.Parent.Type == html.DocumentNode
+}
diff --git a/vendor/github.com/andybalholm/cascadia/selector_test.go b/vendor/github.com/andybalholm/cascadia/selector_test.go
new file mode 100644
index 00000000..7ff77e65
--- /dev/null
+++ b/vendor/github.com/andybalholm/cascadia/selector_test.go
@@ -0,0 +1,654 @@
+package cascadia
+
+import (
+ "bytes"
+ "strings"
+ "testing"
+
+ "golang.org/x/net/html"
+)
+
+type selectorTest struct {
+ HTML, selector string
+ results []string
+}
+
+func nodeString(n *html.Node) string {
+ buf := bytes.NewBufferString("")
+ html.Render(buf, n)
+ return buf.String()
+}
+
+var selectorTests = []selectorTest{
+ {
+ `This address...`,
+ "address",
+ []string{
+ "This address...",
+ },
+ },
+ {
+ `text`,
+ "*",
+ []string{
+ "text",
+ "",
+ "text",
+ },
+ },
+ {
+ ``,
+ "*",
+ []string{
+ "",
+ "",
+ "",
+ },
+ },
+ {
+ `
Fancy a break from the busy streets of Central London? Take in the city wildlife while cruising down charming, cafe-lined Regent's Canal, a historic waterway that was built by hand.
From preferential treatment at the dealership to special consideration on the highway, BBC Autos set out to learn the intangible benefits of buying a big-ticket vehicle.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.
Thoughts and links about programming,
+ by Russ Cox
+
+
+
+
+
+
My Go Resolutions for 2017
+
+
+
+ Posted on Wednesday, January 18, 2017.
+
+
+
+
+
+
’Tis the season for resolutions,
+and I thought it would make sense to write a little
+about what I hope to work on this year as far as Go is concerned.
+
+
My goal every year is to help Go developers.
+I want to make sure that the work we do on the Go team
+has a significant, positive impact on Go developers.
+That may sound obvious, but there are a variety of common ways to fail to achieve that:
+for example, spending too much time cleaning up or optimizing code that doesn’t need it;
+responding only to the most common or recent complaints or requests;
+or focusing too much on short-term improvements.
+It’s important to step back and make sure we’re focusing
+our development work where it does the most good.
+
+
This post outlines a few of my own major focuses for this year.
+This is only my personal list, not the Go team’s list.
+
+
One reason for posting this is to gather feedback.
+If these spark any ideas or suggestions of your own,
+please feel free to comment below or on the linked GitHub issues.
+
+
Another reason is to make clear that I’m aware of these issues as important.
+I think too often people interpret lack of action by the Go team
+as a signal that we think everything is perfect, when instead
+there is simply other, higher priority work to do first.
+
+
Type aliases
+
+
There is a recurring problem with moving types
+from one package to another during large codebase refactorings.
+We tried to solve it last year with general aliases,
+which didn’t work for at least two reasons: we didn’t explain the change well enough,
+and we didn’t deliver it on time, so it wasn’t ready for Go 1.8.
+Learning from that experience,
+I gave a talk
+and wrote an article
+about the underlying problem,
+and that started a productive discussion
+on the Go issue tracker about the solution space.
+It looks like more limited type aliases
+are the right next step.
+I want to make sure those land smoothly in Go 1.9. #18130.
+
+
Package management
+
+
I designed the Go support for downloading published packages
+(“goinstall”, which became “go get”) in February 2010.
+A lot has happened since then.
+In particular, other language ecosystems have really raised the bar
+for what people expect from package management,
+and the open source world has mostly agreed on
+semantic versioning, which provides a useful base
+for inferring version compatibility.
+Go needs to do better here, and a group of contributors have been
+working on a solution.
+I want to make sure these ideas are integrated well
+into the standard Go toolchain and to make package management
+a reason that people love Go.
+
+
Build improvements
+
+
There are a handful of shortcomings in the design of
+the go command’s build system that are overdue to be fixed.
+Here are three representative examples that I intend to
+address with a bit of a redesign of the internals of the go command.
+
+
Builds can be too slow,
+because the go command doesn’t cache build results as aggressively as it should.
+Many people don’t realize that goinstall saves its work while gobuild does not,
+and then they run repeated gobuild commands that are slow
+because the later builds do more work than they should need to.
+The same for repeated gotest without gotest-i when dependencies are modified.
+All builds should be as incremental as possible.
+#4719.
+
+
Test results should be cached too:
+if none of the inputs to a test have changed,
+then usually there is no need to rerun the test.
+This will make it very cheap to run “all tests” when little or nothing has changed.
+#11193.
+
+
Work outside GOPATH should be supported nearly as well
+as work inside GOPATH.
+In particular, it should be possible to gitclone a repo,
+cd into it, and run go commands and have them work fine.
+Package management only makes that more important:
+you’ll need to be able to work on different versions of a package (say, v1 and v2)
+without having entirely separate GOPATHs for them.
+#17271.
+
+
Code corpus
+
+
I think it helped to have concrete examples from real projects
+in the talk and article I prepared about codebase refactoring (see above).
+We’ve also defined that additions to vet
+must target problems that happen frequently in real programs.
+I’d like to see that kind of analysis of actual practice—examining
+the effects on and possible improvements to real programs—become a
+standard way we discuss and evaluate changes to Go.
+
+
Right now there’s not an agreed-upon representative corpus of code to use for
+those analyses: everyone must first create their own, which is too much work.
+I’d like to put together a single, self-contained Git repo people can check out that
+contains our official baseline corpus for those analyses.
+A possible starting point could be the top 100 Go language repos
+on GitHub by stars or forks or both.
+
+
Automatic vet
+
+
The Go distribution ships with this powerful tool,
+govet,
+that points out correctness bugs.
+We have a high bar for checks, so that when vet speaks, you should listen.
+But everyone has to remember to run it.
+It would be better if you didn’t have to remember.
+In particular, I think we could probably run vet
+in parallel with the final compile and link of the test binary
+during gotest without slowing the compile-edit-test cycle at all.
+If we can do that, and if we limit the enabled vet checks to a subset
+that is essentially 100% accurate,
+we can make passing vet a precondition for running a test at all.
+Then developers don’t need to remember to run govet.
+They run gotest,
+and once in a while vet speaks up with something important
+and avoids a debugging session.
+#18084,
+#18085.
+
+
Errors & best practices
+
+
Part of the intended contract for error reporting in Go is that functions
+include relevant available context, including the operation being attempted
+(such as the function name and its arguments).
+For example, this program:
Not enough Go code adds context like os.Remove does. Too much code does only
+
+
if err != nil {
+ return err
+}
+
+
+
all the way up the call stack,
+discarding useful context that should be reported
+(like remove/tmp/nonexist: above).
+I would like to try to understand whether our expectations
+for including context are wrong, or if there is something
+we can do to make it easier to write code that returns better errors.
+
+
There are also various discussions in the community about
+agreed-upon interfaces for stripping error context.
+I would like to try to understand when that makes sense and
+whether we should adopt an official recommendation.
+
+
Context & best practices
+
+
We added the new context package
+in Go 1.7 for holding request-scoped information like
+timeouts, cancellation state, and credentials.
+An individual context is immutable (like an individual string or int):
+it is only possible to derive a new, updated context and
+pass that context explicitly further down the call stack or
+(less commonly) back up to the caller.
+The context is now carried through APIs such as
+database/sql
+and
+net/http,
+mainly so that those can stop processing a request when the caller
+is no longer interested in the result.
+Timeout information is appropriate to carry in a context,
+but—to use a real example we removed—database options
+are not, because they are unlikely to apply equally well to all possible
+database operations carried out during a request.
+What about the current clock source, or logging sink?
+Is either of those appropriate to store in a context?
+I would like to try to understand and characterize the
+criteria for what is and is not an appropriate use of context.
+
+
Memory model
+
+
Go’s memory model is intentionally low-key,
+making few promises to users, compared to other languages.
+In fact it starts by discouraging people from reading the rest of the document.
+At the same time, it demands more of the compiler than other languages:
+in particular, a race on an integer value is not sufficient license
+for your program to misbehave in arbitrary ways.
+But there are some complete gaps, in particular no mention of
+the sync/atomic package.
+I think the core compiler and runtime developers all agree
+that the behavior of those atomics should be roughly the same as
+C++ seqcst atomics or Java volatiles,
+but we still need to write that down carefully in the memory model,
+and probably also in a long blog post.
+#5045,
+#7948,
+#9442.
+
+
Immutability
+
+
The race detector
+is one of Go’s most loved features.
+But not having races would be even better.
+I would love it if there were some reasonable way to integrate
+reference immutability into Go,
+so that programmers can make clear, checked assertions about what can and cannot
+be written and thereby eliminate certain races at compile time.
+Go already has one immutable type, string; it would
+be nice to retroactively define that
+string is a named type (or type alias) for immutable[]byte.
+I don’t think that will happen this year,
+but I’d like to understand the solution space better.
+Javari, Midori, Pony, and Rust have all staked out interesting points
+in the solution space, and there are plenty of research papers
+beyond those.
+
+
In the long-term, if we could statically eliminate the possibility of races,
+that would eliminate the need for most of the memory model.
+That may well be an impossible dream,
+but again I’d like to understand the solution space better.
+
+
Generics
+
+
Nothing sparks more heated arguments
+among Go and non-Go developers than the question of whether Go should
+have support for generics (or how many years ago that should have happened).
+I don’t believe the Go team has ever said “Go does not need generics.”
+What we have said is that there are higher-priority issues facing Go.
+For example, I believe that better support for package management
+would have a much larger immediate positive impact on most Go developers
+than adding generics.
+But we do certainly understand that for a certain subset of Go use cases,
+the lack of parametric polymorphism is a significant hindrance.
+
+
Personally, I would like to be able to write general channel-processing
+functions like:
+
+
// Join makes all messages received on the input channels
+// available for receiving from the returned channel.
+func Join(inputs ...<-chan T) <-chan T
+
+// Dup duplicates messages received on c to both c1 and c2.
+func Dup(c <-chan T) (c1, c2 <-chan T)
+
+
+
I would also like to be able to write
+Go support for high-level data processing abstractions,
+analogous to
+FlumeJava or
+C#’s LINQ,
+in a way that catches type errors at compile time instead of at run time.
+There are also any number of data structures or generic algorithms
+that might be written,
+but I personally find these broader applications more compelling.
+
+
We’ve struggled off and on
+for years
+to find the right way to add generics to Go.
+At least a few of the past proposals got hung up on trying to design
+something that provided both general parametric polymorphism
+(like chanT) and also a unification of string and []byte.
+If the latter is handled by parameterization over immutability,
+as described in the previous section, then maybe that simplifies
+the demands on a design for generics.
+
+
When I first started thinking about generics for Go in 2008,
+the main examples to learn from were C#, Java, Haskell, and ML.
+None of the approaches in those languages seemed like a
+perfect fit for Go.
+Today, there are newer attempts to learn from as well,
+including Dart, Midori, Rust, and Swift.
+
+
It’s been a few years since we ventured out and explored the design space.
+It is probably time to look around again,
+especially in light of the insight about mutability and
+the additional examples set by newer languages.
+I don’t think generics will happen this year,
+but I’d like to be able to say I understand the solution space better.
For copyright information, see Ecma International’s legal disclaimer in the document itself.
+
+
+
+
Draft
+
ECMA-262
+
6th Edition / Draft March 17, 2015
+
Ecma/TC39/2015/0XX
+
+
+
ECMAScript 2015
+
Language Specification
+
+
Draft Release Candidate #3
+
+
Report Errors and Issues at: https://bugs.ecmascript.org
+
+
Product: Draft for 6th Edition
+
+
Component: choose an appropriate one
+
+
Version: Rev 36, March 17, 2015 Draft
+
+
+
+
Contents
+
+
+
+
Introduction
+
+
This is the sixth edition of ECMAScript Language Specification. Since publication of the first edition in 1997, ECMAScript
+ has grown to be one of the world’s most widely used general purpose programming languages. It is best known as the
+ language embedded in web browsers but has also been widely adopted for server and embedded applications. The sixth edition is
+ the most extensive update to ECMAScript since the publication of the first edition in 1997.
+
+
Goals for the sixth edition include providing better support for large applications, library creation, and for use of
+ ECMAScript as a compilation target for other languages. Some of its major enhancements include modules, class declarations,
+ lexical block scoping, iterators and generators, promises for asynchronous programming, destructuring patterns, and proper tail
+ calls. The ECMAScript library of built-ins has been expanded to support additional data abstractions including maps, sets, and
+ arrays of binary numeric values as well as additional support for Unicode supplemental characters in strings and regular
+ expressions. The built-ins are now extensible via subclassing.
+
+
Focused development of the sixth edition started in 2009, as the fifth edition was being prepared for publication. However,
+ this was preceded by significant experimentation and language enhancement design efforts dating to the publication of the third
+ edition in 1999. In a very real sense, the completion of the sixth edition is the culmination of a fifteen year effort. Dozens
+ of individuals representing many organizations have made very significant contributions within TC39 to the development of this
+ edition and to the prior editions. In addition, a vibrant informal community has emerged supporting TC39’s ECMAScript
+ efforts. This community has reviewed numerous drafts, filed thousands of bug reports, performed implementation experiments,
+ contributed test suites, and educated the world-wide developer community about ECMAScript. Unfortunately, it is impossible to
+ identify and acknowledge every person and organization who has contributed to this effort.
+
+
New uses and requirements for ECMAScript continue to emerge. The sixth edition provides the foundation for regular,
+ incremental language and library enhancements.
+
+
Allen Wirfs-Brock ECMA-262, 6th Edition Project Editor
+
+
This Ecma Standard has been adopted by the General Assembly of <month> <year>.
+
+
ECMA-262 Edition History
+
+
This Ecma Standard is based on several originating technologies, the most well-known being JavaScript (Netscape) and JScript
+ (Microsoft). The language was invented by Brendan Eich at Netscape and first appeared in that company’s Navigator 2.0
+ browser. It has appeared in all subsequent browsers from Netscape and in all browsers from Microsoft starting with Internet
+ Explorer 3.0.
+
+
The development of this Standard started in November 1996. The first edition of this Ecma Standard was adopted by the Ecma
+ General Assembly of June 1997.
+
+
That Ecma Standard was submitted to ISO/IEC JTC 1 for adoption under the fast-track procedure, and approved as international
+ standard ISO/IEC 16262, in April 1998. The Ecma General Assembly of June 1998 approved the second edition of ECMA-262 to keep it
+ fully aligned with ISO/IEC 16262. Changes between the first and the second edition are editorial in nature.
+
+
The third edition of the Standard introduced powerful regular expressions, better string handling, new control statements,
+ try/catch exception handling, tighter definition of errors, formatting for numeric output and minor changes in anticipation
+ future language growth. The third edition of the ECMAScript standard was adopted by the Ecma General Assembly of December 1999
+ and published as ISO/IEC 16262:2002 in June 2002.
+
+
After publication of the third edition, ECMAScript achieved massive adoption in conjunction with the World Wide Web where it
+ has become the programming language that is supported by essentially all web browsers. Significant work was done to develop a
+ fourth edition of ECMAScript. However, that work was not completed and not published as the fourth edition of ECMAScript but
+ some of it was incorporated into the development of the sixth edition.
+
+
The fifth edition of ECMAScript (published as ECMA-262 5th edition) codified de facto interpretations of the
+ language specification that have become common among browser implementations and added support for new features that had emerged
+ since the publication of the third edition. Such features include accessor properties, reflective creation and inspection of
+ objects, program control of property attributes, additional array manipulation functions, support for the JSON object encoding
+ format, and a strict mode that provides enhanced error checking and program security. The Fifth Edition was adopted by the Ecma
+ General Assembly of December 2009.
+
+
The Fifth Edition was submitted to ISO/IEC JTC 1 for adoption under the fast-track procedure, and approved as international
+ standard ISO/IEC 16262:2011. Edition 5.1 of the ECMAScript Standard incorporated minor corrections and is the same text as
+ ISO/IEC 16262:2011. The 5.1 Edition was adopted by the Ecma General Assembly of June 2011.
+
+
"DISCLAIMER
+
+
This draft document may be copied and furnished to others, and derivative works that comment on or otherwise explain it or
+ assist in its implementation may be prepared, copied, published, and distributed, in whole or in part, without restriction of
+ any kind, provided that the above copyright notice and this section are included on all such copies and derivative works.
+ However, this document itself may not be modified in any way, including by removing the copyright notice or references to Ecma
+ International, except as needed for the purpose of developing any document or deliverable produced by Ecma
+ International.
+
+
This disclaimer is valid only prior to final version of this document. After approval all rights on the standard are
+ reserved by Ecma International.
+
+
The limited permissions are granted through the standardization phase and will not be revoked by Ecma International or its
+ successors or assigns during this time.
+
+
This document and the information contained herein is provided on an "AS IS" basis and ECMA INTERNATIONAL DISCLAIMS ALL
+ WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT
+ INFRINGE ANY OWNERSHIP RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
A conforming implementation of ECMAScript must provide and support all the types, values, objects, properties, functions, and
+ program syntax and semantics described in this specification.
+
+
A conforming implementation of ECMAScript must interpret source text input in conformance with the Unicode Standard, Version
+ 5.1.0 or later and ISO/IEC 10646. If the adopted ISO/IEC 10646-1 subset is not otherwise specified, it is presumed to be the
+ Unicode set, collection 10646.
+
+
A conforming implementation of ECMAScript that provides an application programming interface that supports programs that need
+ to adapt to the linguistic and cultural conventions used by different human languages and countries must implement the interface
+ defined by the most recent edition of ECMA-402 that is compatible with this specification.
+
+
A conforming implementation of ECMAScript may provide additional types, values, objects, properties, and functions beyond
+ those described in this specification. In particular, a conforming implementation of ECMAScript may provide properties not
+ described in this specification, and values for those properties, for objects that are described in this specification.
+
+
A conforming implementation of ECMAScript may support program and regular expression syntax not described in this
+ specification. In particular, a conforming implementation of ECMAScript may support program syntax that makes use of the
+ “future reserved words” listed in subclause 11.6.2.2 of this
+ specification.
+
+
A conforming implementation of ECMAScript must not implement any extension that is listed as a Forbidden Extension in subclause 16.1.
The following referenced documents are indispensable for the application of this document. For dated references, only the
+ edition cited applies. For undated references, the latest edition of the referenced document (including any amendments)
+ applies.
+
+
IEEE Std 754-2008: IEEE Standard for Floating-Point Arithmetic. Institute of Electrical and
+ Electronic Engineers, New York (2008)
+
+
ISO/IEC 10646:2003: Information Technology – Universal Multiple-Octet Coded Character Set
+ (UCS) plus Amendment 1:2005, Amendment 2:2006, Amendment 3:2008, and Amendment 4:2008, plus additional amendments and
+ corrigenda, or successor
This section contains a non-normative overview of the ECMAScript language.
+
+
ECMAScript is an object-oriented programming language for performing computations and manipulating computational objects
+ within a host environment. ECMAScript as defined here is not intended to be computationally self-sufficient; indeed, there are
+ no provisions in this specification for input of external data or output of computed results. Instead, it is expected that the
+ computational environment of an ECMAScript program will provide not only the objects and other facilities described in this
+ specification but also certain environment-specific objects, whose description and behaviour are beyond the scope of this
+ specification except to indicate that they may provide certain properties that can be accessed and certain functions that can
+ be called from an ECMAScript program.
+
+
ECMAScript was originally designed to be used as a scripting language, but has become widely used as a general purpose
+ programming language. A scripting language is a programming language that is used to manipulate, customize, and
+ automate the facilities of an existing system. In such systems, useful functionality is already available through a user
+ interface, and the scripting language is a mechanism for exposing that functionality to program control. In this way, the
+ existing system is said to provide a host environment of objects and facilities, which completes the capabilities of the
+ scripting language. A scripting language is intended for use by both professional and non-professional programmers.
+
+
ECMAScript was originally designed to be a Web scripting language, providing a mechanism to enliven Web pages
+ in browsers and to perform server computation as part of a Web-based client-server architecture. ECMAScript is now used to
+ provide core scripting capabilities for a variety of host environments. Therefore the core language is specified in this
+ document apart from any particular host environment.
+
+
ECMAScript usage has moved beyond simple scripting and it is now used for the full spectrum of programming tasks in many
+ different environments and scales. As the usage of ECMAScript has expanded, so has the features and facilities it provides.
+ ECMAScript is now a fully featured general propose programming language.
+
+
Some of the facilities of ECMAScript are similar to those used in other programming languages; in particular C,
+ Java™, Self, and Scheme as described in:
+
+
ISO/IEC 9899:1996, Programming Languages – C.
+
+
Gosling, James, Bill Joy and Guy Steele. The Java™ Language
+ Specification. Addison Wesley Publishing Co., 1996.
+
+
Ungar, David, and Smith, Randall B. Self: The Power of Simplicity.
+ OOPSLA '87 Conference Proceedings, pp. 227–241, Orlando, FL, October 1987.
+
+
IEEE Standard for the Scheme Programming Language. IEEE Std
+ 1178-1990.
A web browser provides an ECMAScript host environment for client-side computation including, for instance, objects that
+ represent windows, menus, pop-ups, dialog boxes, text areas, anchors, frames, history, cookies, and input/output. Further, the
+ host environment provides a means to attach scripting code to events such as change of focus, page and image loading,
+ unloading, error and abort, selection, form submission, and mouse actions. Scripting code appears within the HTML and the
+ displayed page is a combination of user interface elements and fixed and computed text and images. The scripting code is
+ reactive to user interaction and there is no need for a main program.
+
+
A web server provides a different host environment for server-side computation including objects representing requests,
+ clients, and files; and mechanisms to lock and share data. By using browser-side and server-side scripting together, it is
+ possible to distribute computation between the client and server while providing a customized user interface for a Web-based
+ application.
+
+
Each Web browser and server that supports ECMAScript supplies its own host environment, completing the ECMAScript execution
+ environment.
The following is an informal overview of ECMAScript—not all parts of the language are described. This overview is
+ not part of the standard proper.
+
+
ECMAScript is object-based: basic language and host facilities are provided by objects, and an ECMAScript program is a
+ cluster of communicating objects. In ECMAScript, an object is a collection of zero or more
+ properties each with attributes that determine how each property can be used—for example,
+ when the Writable attribute for a property is set to false, any attempt by executed ECMAScript code to assign a
+ different value to the property fails. Properties are containers that hold other objects, primitive values, or
+ functions. A primitive value is a member of one of the following built-in types: Undefined,
+ Null, Boolean, Number, String, and Symbol; an object is a member of the built-in type
+ Object; and a function is a callable object. A function that is associated with an object via a property is called a
+ method.
+
+
ECMAScript defines a collection of built-in objects that round out the definition of ECMAScript entities.
+ These built-in objects include the global object; objects that are fundamental to the runtime semantics of the language
+ including Object, Function, Boolean, Symbol, and various Error objects; objects that
+ represent and manipulate numeric values including Math, Number, and Date; the text processing objects
+ String and RegExp; objects that are indexed collections of values including Array and nine different
+ kinds of Typed Arrays whose elements all have a specific numeric data representation; keyed collections including Map
+ and Set objects; objects supporting structured data including the JSON object, ArrayBuffer, and
+ DataView; objects supporting control abstractions including generator functions and Promise objects;
+ and, reflection objects including Proxy and Reflect.
+
+
ECMAScript also defines a set of built-in operators. ECMAScript operators include various unary operations,
+ multiplicative operators, additive operators, bitwise shift operators, relational operators, equality operators, binary
+ bitwise operators, binary logical operators, assignment operators, and the comma operator.
+
+
Large ECMAScript programs are supported by modules which allow a program to be divided into multiple
+ sequences of statements and declarations. Each module explicitly identifies declarations it uses that need to be provided by
+ other modules and which of its declarations are available for use by other modules.
+
+
ECMAScript syntax intentionally resembles Java syntax. ECMAScript syntax is relaxed to enable it to serve as an
+ easy-to-use scripting language. For example, a variable is not required to have its type declared nor are types associated
+ with properties, and defined functions are not required to have their declarations appear textually before calls to
+ them.
Even though ECMAScript includes syntax for class definitions, ECMAScript objects are not fundamentally class-based such
+ as those in C++, Smalltalk, or Java. Instead objects may be created in various ways including via a literal notation or via
+ constructors which create objects and then execute code that initializes all or part of them by assigning
+ initial values to their properties. Each constructor is a function that has a property named "prototype" that
+ is used to implement prototype-based inheritance and shared properties. Objects are created by
+ using constructors in new expressions; for example, new Date(2009,11) creates a new Date object.
+ Invoking a constructor without using new has consequences that depend on the constructor. For example,
+ Date() produces a string representation of the current date and time rather than an object.
+
+
Every object created by a constructor has an implicit reference (called the object’s prototype) to the value
+ of its constructor’s "prototype" property. Furthermore, a prototype may have a non-null implicit
+ reference to its prototype, and so on; this is called the prototype chain. When a reference is made to a property in
+ an object, that reference is to the property of that name in the first object in the prototype chain that contains a
+ property of that name. In other words, first the object mentioned directly is examined for such a property; if that object
+ contains the named property, that is the property to which the reference refers; if that object does not contain the named
+ property, the prototype for that object is examined next; and so on.
+
+
+
+
In a class-based object-oriented language, in general, state is carried by instances, methods are carried by classes, and
+ inheritance is only of structure and behaviour. In ECMAScript, the state and methods are carried by objects, while
+ structure, behaviour, and state are all inherited.
+
+
All objects that do not directly contain a particular property that their prototype contains share that property and its
+ value. Figure 1 illustrates this:
+
+
CF is a constructor (and also an object). Five objects have been created by using new expressions:
+ cf1, cf2, cf3, cf4, and cf5. Each
+ of these objects contains properties named q1 and q2. The dashed lines represent the implicit
+ prototype relationship; so, for example, cf3’s prototype is CFp. The constructor,
+ CF, has two properties itself, named P1 and P2, which are not visible to
+ CFp, cf1, cf2, cf3, cf4, or
+ cf5. The property named CFP1 in CFp is shared by cf1,
+ cf2, cf3, cf4, and cf5 (but not by CF), as
+ are any properties found in CFp’s implicit prototype chain that are not named q1,
+ q2, or CFP1. Notice that there is no implicit prototype link between CF and
+ CFp.
+
+
Unlike most class-based object languages, properties can be added to objects dynamically by assigning values to them.
+ That is, constructors are not required to name or assign values to all or any of the constructed object’s properties.
+ In the above diagram, one could add a new shared property for cf1, cf2,
+ cf3, cf4, and cf5 by assigning a new value to the property in
+ CFp.
+
+
Although ECMAScript objects are not inherently class-based, it is often convenient to define class-like abstractions
+ based upon a common pattern of constructor functions, prototype objects, and methods. The ECMAScript built-in objects
+ themselves follow such a class-like pattern. Beginning with the sixth edition, the ECMAScript language includes syntactic
+ class definitions that permit programmers to concisely define objects that conform to the same class-like abstraction
+ pattern used by the built-in objects.
The ECMAScript Language recognizes the possibility that some users of the language may wish to restrict their usage of
+ some features available in the language. They might do so in the interests of security, to avoid what they consider to be
+ error-prone features, to get enhanced error checking, or for other reasons of their choosing. In support of this
+ possibility, ECMAScript defines a strict variant of the language. The strict variant of the language excludes some specific
+ syntactic and semantic features of the regular ECMAScript language and modifies the detailed semantics of some features. The
+ strict variant also specifies additional error conditions that must be reported by throwing error exceptions in situations
+ that are not specified as errors by the non-strict form of the language.
+
+
The strict variant of ECMAScript is commonly referred to as the strict mode of the language. Strict mode selection
+ and use of the strict mode syntax and semantics of ECMAScript is explicitly made at the level of individual ECMAScript
+ source text units. Because strict mode is selected at the level of a syntactic source text unit, strict mode only imposes
+ restrictions that have local effect within such a source text unit. Strict mode does not restrict or modify any aspect of
+ the ECMAScript semantics that must operate consistently across multiple source text units. A complete ECMAScript program may
+ be composed of both strict mode and non-strict mode ECMAScript source text units. In this case, strict mode only applies
+ when actually executing code that is defined within a strict mode source text unit.
+
+
In order to conform to this specification, an ECMAScript implementation must implement both the full unrestricted
+ ECMAScript language and the strict variant of the ECMAScript language as defined by this specification. In addition, an
+ implementation must support the combination of unrestricted and strict mode source text units into a single composite
+ program.
object that provides shared properties for other objects
+
+
+
NOTE When a constructor creates an object, that object implicitly references the
+ constructor’s prototype property for the purpose of resolving property references. The
+ constructor’s prototype property can be referenced by the program expression
+ constructor.prototype, and properties added to an object’s prototype are shared, through
+ inheritance, by all objects sharing the prototype. Alternatively, a new object may be created with an explicitly specified
+ prototype by using the Object.create built-in function.
object specified and supplied by an ECMAScript implementation
+
+
+
NOTE Standard built-in objects are defined in this specification. An ECMAScript implementation
+ may specify and supply additional kinds of built-in objects. A built-in constructor is a built-in object that is
+ also a constructor.
member of the Object type that is an instance of the standard built-in Boolean constructor
+
+
+
NOTE A Boolean object is created by using the Boolean constructor in a
+ new expression, supplying a Boolean value as an argument. The resulting object has an internal slot whose value is the Boolean value. A Boolean
+ object can be coerced to a Boolean value.
primitive value that is a finite ordered sequence of zero or more 16-bit unsigned integer
+
+
+
NOTE A String value is a member of the String type. Each integer value in the sequence usually
+ represents a single 16-bit unit of UTF-16 text. However, ECMAScript does not place any restrictions or requirements on the
+ values except that they must be 16-bit unsigned integers.
member of the Object type that is an instance of the standard built-in String constructor
+
+
+
NOTE A String object is created by using the String constructor in a
+ new expression, supplying a String value as an argument. The resulting object has an internal slot whose value is the String value. A String object
+ can be coerced to a String value by calling the String constructor as a function (21.1.1.1).
member of the Object type that is an instance of the standard built-in Number constructor
+
+
+
NOTE A Number object is created by using the Number constructor in a
+ new expression, supplying a Number value as an argument. The resulting object has an internal slot whose value is the Number value. A Number object
+ can be coerced to a Number value by calling the Number constructor as a function (20.1.1.1).
member of the Object type that may be invoked as a subroutine
+
+
+
NOTE In addition to its properties, a function contains executable code and state that
+ determine how it behaves when invoked. A function’s code may or may not be written in ECMAScript.
NOTE Examples of built-in functions include parseInt and Math.exp. An implementation may provide implementation-dependent built-in functions that
+ are not described in this specification.
part of an object that associates a key (either a String value or a Symbol value) and a value.
+
+
+
NOTE Depending upon the form of the property the value may be represented either directly as a
+ data value (a primitive value, an object, or a function object) or indirectly by a pair of accessor functions.
NOTE Standard built-in methods are defined in this specification, and an ECMAScript
+ implementation may specify and provide other additional built-in methods.
The remainder of this specification is organized as follows:
+
+
Clause 5 defines the notational conventions used throughout the specification.
+
+
Clauses 6−9 define the execution environment within which ECMAScript programs operate.
+
+
Clauses 10−16 define the actual ECMAScript programming language including its syntactic encoding and the execution
+ semantics of all language features.
+
+
Clauses 17−26 define the ECMAScript standard library. It includes the definitions of all of the standard objects that
+ are available for use by ECMAScript programs as they execute.
A context-free grammar consists of a number of productions. Each production has an abstract symbol called a
+ nonterminal as its left-hand side, and a sequence of zero or more nonterminal and terminal symbols as
+ its right-hand side. For each grammar, the terminal symbols are drawn from a specified alphabet.
+
+
A chain production is a production that has exactly one nonterminal symbol on its right-hand side along with zero
+ or more terminal symbols.
+
+
Starting from a sentence consisting of a single distinguished nonterminal, called the goal symbol, a given
+ context-free grammar specifies a language, namely, the (perhaps infinite) set of possible sequences of terminal
+ symbols that can result from repeatedly replacing any nonterminal in the sequence with a right-hand side of a production for
+ which the nonterminal is the left-hand side.
A lexical grammar for ECMAScript is given in clause 11.
+ This grammar has as its terminal symbols Unicode code points that conform to the rules for SourceCharacter defined in 10.1. It defines a set of productions, starting
+ from the goal symbol InputElementDiv,InputElementTemplateTail, or InputElementRegExp, or InputElementRegExpOrTemplateTail, that describe how sequences of such
+ code points are translated into a sequence of input elements.
+
+
Input elements other than white space and comments form the terminal symbols for the syntactic grammar for ECMAScript and
+ are called ECMAScript tokens. These tokens are the reserved words, identifiers, literals, and punctuators of the
+ ECMAScript language. Moreover, line terminators, although not considered to be tokens, also become part of the stream of
+ input elements and guide the process of automatic semicolon insertion (11.9). Simple white space and single-line comments are discarded and do not
+ appear in the stream of input elements for the syntactic grammar. A MultiLineComment (that is, a
+ comment of the form /*…*/ regardless of whether it spans more than one line) is likewise
+ simply discarded if it contains no line terminator; but if a MultiLineComment contains one or more
+ line terminators, then it is replaced by a single line terminator, which becomes part of the stream of input elements for
+ the syntactic grammar.
+
+
A RegExp grammar for ECMAScript is given in 21.2.1. This grammar also has as its
+ terminal symbols the code points as defined by SourceCharacter. It defines a set of productions,
+ starting from the goal symbol Pattern, that describe how sequences of code points are translated
+ into regular expression patterns.
+
+
Productions of the lexical and RegExp grammars are distinguished by having two colons “::” as
+ separating punctuation. The lexical and RegExp grammars share some productions.
Another grammar is used for translating Strings into numeric values. This grammar is similar to the part of the lexical
+ grammar having to do with numeric literals and has as its terminal symbols SourceCharacter. This
+ grammar appears in 7.1.3.1.
+
+
Productions of the numeric string grammar are distinguished by having three colons “:::” as
+ punctuation.
The syntactic grammar for ECMAScript is given in clauses 11, 12, 13, 14, and 15. This grammar has ECMAScript
+ tokens defined by the lexical grammar as its terminal symbols (5.1.2). It
+ defines a set of productions, starting from two alternative goal symbols Script and Module, that describe how sequences of tokens form syntactically correct independent components of
+ ECMAScript programs.
+
+
When a stream of code points is to be parsed as an ECMAScript Script or Module, it is first converted to a stream of input elements by repeated application of the lexical
+ grammar; this stream of input elements is then parsed by a single application of the syntactic grammar. The input stream is
+ syntactically in error if the tokens in the stream of input elements cannot be parsed as a single instance of the goal
+ nonterminal (Script or Module), with no tokens left over.
+
+
Productions of the syntactic grammar are distinguished by having just one colon “:” as
+ punctuation.
+
+
The syntactic grammar as presented in clauses 12, 13, 14 and 15 is not a complete account of which token sequences are
+ accepted as a correct ECMAScript Script or Module. Certain additional token
+ sequences are also accepted, namely, those that would be described by the grammar if only semicolons were added to the
+ sequence in certain places (such as before line terminator characters). Furthermore, certain token sequences that are
+ described by the grammar are not considered acceptable if a line terminator character appears in certain
+ “awkward” places.
+
+
In certain cases in order to avoid ambiguities the syntactic grammar uses generalized productions that permit token
+ sequences that do not form a valid ECMAScript Script or Module. For example,
+ this technique is used for object literals and object destructuring patterns. In such cases a more restrictive
+ supplemental grammar is provided that further restricts the acceptable token sequences. In certain contexts, when
+ explicitly specified, the input elements corresponding to such a production are parsed again using a goal symbol of a
+ supplemental grammar. The input stream is syntactically in error if the tokens in the stream of input elements parsed by a
+ cover grammar cannot be parsed as a single instance of the corresponding supplemental goal symbol, with no tokens left
+ over.
Terminal symbols of the lexical, RegExp, and numeric string grammars are shown in fixed width font, both in
+ the productions of the grammars and throughout this specification whenever the text directly refers to such a terminal
+ symbol. These are to appear in a script exactly as written. All terminal symbol code points specified in this way are to be
+ understood as the appropriate Unicode code points from the Basic Latin range, as opposed to any similar-looking code points
+ from other Unicode ranges.
+
+
Nonterminal symbols are shown in italic type. The definition of a nonterminal (also called a
+ “production”) is introduced by the name of the nonterminal being defined followed by one or more colons. (The
+ number of colons indicates to which grammar the production belongs.) One or more alternative right-hand sides for the
+ nonterminal then follow on succeeding lines. For example, the syntactic definition:
+
+
+
WhileStatement:
+
while(Expression)Statement
+
+
+
states that the nonterminal WhileStatement represents the token while, followed by a
+ left parenthesis token, followed by an Expression, followed by a right parenthesis token, followed
+ by a Statement. The occurrences of Expression and Statement are themselves nonterminals. As another example, the syntactic definition:
+
+
+
ArgumentList:
+
AssignmentExpression
+
ArgumentList,AssignmentExpression
+
+
+
states that an ArgumentList may represent either a single AssignmentExpression or an ArgumentList, followed by a comma, followed by an AssignmentExpression. This definition of ArgumentList is recursive, that is, it is
+ defined in terms of itself. The result is that an ArgumentList may contain any positive number of
+ arguments, separated by commas, where each argument expression is an AssignmentExpression. Such
+ recursive definitions of nonterminals are common.
+
+
The subscripted suffix “opt”, which may appear after a terminal or nonterminal, indicates an
+ optional symbol. The alternative containing the optional symbol actually specifies two right-hand sides, one that omits the
+ optional element and one that includes it. This means that:
so, in this example, the nonterminal IterationStatement actually has four alternative right-hand
+ sides.
+
+
A production may be parameterized by a subscripted annotation of the form “[parameters]”, which
+ may appear as a suffix to the nonterminal symbol defined by the production. “parameters” may be
+ either a single name or a comma separated list of names. A parameterized production is shorthand for a set of productions
+ defining all combinations of the parameter names, preceded by an underscore, appended to the parameterized nonterminal
+ symbol. This means that:
+
+
+
StatementList[Return]:
+
ReturnStatement
+
ExpressionStatement
+
+
+
is a convenient abbreviation for:
+
+
+
StatementList:
+
ReturnStatement
+
ExpressionStatement
+
+
+
+
StatementList_Return:
+
ReturnStatement
+
ExpressionStatement
+
+
+
and that:
+
+
+
StatementList[Return, In]:
+
ReturnStatement
+
ExpressionStatement
+
+
+
is an abbreviation for:
+
+
+
StatementList:
+
ReturnStatement
+
ExpressionStatement
+
+
+
+
StatementList_Return:
+
ReturnStatement
+
ExpressionStatement
+
+
+
+
StatementList_In:
+
ReturnStatement
+
ExpressionStatement
+
+
+
+
StatementList_Return_In:
+
ReturnStatement
+
ExpressionStatement
+
+
+
Multiple parameters produce a combinatory number of productions, not all of which are necessarily referenced in a
+ complete grammar.
+
+
References to nonterminals on the right-hand side of a production can also be parameterized. For example:
+
+
+
StatementList:
+
ReturnStatement
+
ExpressionStatement[In]
+
+
+
is equivalent to saying:
+
+
+
StatementList:
+
ReturnStatement
+
ExpressionStatement_In
+
+
+
A nonterminal reference may have both a parameter list and an “opt” suffix. For example:
+
+
+
VariableDeclaration:
+
BindingIdentifierInitializer[In]opt
+
+
+
is an abbreviation for:
+
+
+
VariableDeclaration:
+
BindingIdentifier
+
BindingIdentifierInitializer_In
+
+
+
Prefixing a parameter name with “?” on a right-hand side nonterminal reference makes that
+ parameter value dependent upon the occurrence of the parameter name on the reference to the current production’s
+ left-hand side symbol. For example:
+
+
+
VariableDeclaration[In]:
+
BindingIdentifierInitializer[?In]
+
+
+
is an abbreviation for:
+
+
+
VariableDeclaration:
+
BindingIdentifierInitializer
+
+
+
+
VariableDeclaration_In:
+
BindingIdentifierInitializer_In
+
+
+
If a right-hand side alternative is prefixed with “[+parameter]” that alternative is only available if the
+ named parameter was used in referencing the production’s nonterminal symbol. If a right-hand side alternative is
+ prefixed with “[~parameter]” that alternative is only available if the named parameter was not used in
+ referencing the production’s nonterminal symbol. This means that:
+
+
+
StatementList[Return]:
+
[+Return]ReturnStatement
+
ExpressionStatement
+
+
+
is an abbreviation for:
+
+
+
StatementList:
+
ExpressionStatement
+
+
+
+
StatementList_Return:
+
ReturnStatement
+
ExpressionStatement
+
+
+
and that
+
+
+
StatementList[Return]:
+
[~Return]ReturnStatement
+
ExpressionStatement
+
+
+
is an abbreviation for:
+
+
+
StatementList:
+
ReturnStatement
+
ExpressionStatement
+
+
+
+
StatementList_Return:
+
ExpressionStatement
+
+
+
When the words “one of” follow the colon(s) in a grammar definition, they signify that each of the
+ terminal symbols on the following line or lines is an alternative definition. For example, the lexical grammar for
+ ECMAScript contains the production:
+
+
+
NonZeroDigit::one of
+
123456789
+
+
+
which is merely a convenient abbreviation for:
+
+
+
NonZeroDigit::
+
1
+
2
+
3
+
4
+
5
+
6
+
7
+
8
+
9
+
+
+
If the phrase “[empty]” appears as the right-hand side of a production, it indicates that the production's
+ right-hand side contains no terminals or nonterminals.
+
+
If the phrase “[lookahead ∉ set]” appears in the right-hand side of a production, it
+ indicates that the production may not be used if the immediately following input token is a member of the given
+ set. The set can be written as a list of terminals enclosed in curly brackets. For convenience, the
+ set can also be written as a nonterminal, in which case it represents the set of all terminals to which that nonterminal
+ could expand. If the set consists of a single terminal the phrase “[lookahead ≠
+ terminal]” may be used.
+
+
For example, given the definitions
+
+
+
DecimalDigit::one of
+
0123456789
+
+
+
+
DecimalDigits::
+
DecimalDigit
+
DecimalDigitsDecimalDigit
+
+
+
the definition
+
+
+
LookaheadExample::
+
n[lookahead ∉ {1, 3, 5, 7, 9}]DecimalDigits
+
DecimalDigit[lookahead ∉ DecimalDigit]
+
+
+
matches either the letter n followed by one or more decimal digits the first of which is even, or a decimal
+ digit not followed by another decimal digit.
+
+
If the phrase “[no LineTerminator here]” appears in the right-hand side of a
+ production of the syntactic grammar, it indicates that the production is a restricted production: it may not be used
+ if a LineTerminator occurs in the input stream at the indicated position. For example, the
+ production:
+
+
+
ThrowStatement:
+
throw[no LineTerminator here]Expression;
+
+
+
indicates that the production may not be used if a LineTerminator occurs in the script between
+ the throw token and the Expression.
+
+
Unless the presence of a LineTerminator is forbidden by a restricted production, any number of
+ occurrences of LineTerminator may appear between any two consecutive tokens in the stream of input
+ elements without affecting the syntactic acceptability of the script.
+
+
When an alternative in a production of the lexical grammar or the numeric string grammar appears to be a multi-code point
+ token, it represents the sequence of code points that would make up such a token.
+
+
The right-hand side of a production may specify that certain expansions are not permitted by using the phrase
+ “but not” and then indicating the expansions to be excluded. For example, the production:
+
+
+
Identifier::
+
IdentifierNamebut notReservedWord
+
+
+
means that the nonterminal Identifier may be replaced by any sequence of code points that could
+ replace IdentifierName provided that the same sequence of code points could not replace ReservedWord.
+
+
Finally, a few nonterminal symbols are described by a descriptive phrase in sans-serif type in cases where it would be
+ impractical to list all the alternatives:
The specification often uses a numbered list to specify steps in an algorithm. These algorithms are used to precisely
+ specify the required semantics of ECMAScript language constructs. The algorithms are not intended to imply the use of any
+ specific implementation technique. In practice, there may be more efficient algorithms available to implement a given
+ feature.
+
+
Algorithms may be explicitly parameterized, in which case the names and usage of the parameters must be provided as part of
+ the algorithm’s definition. In order to facilitate their use in multiple parts of this specification, some algorithms,
+ called abstractoperations, are named and written in parameterized functional form so that they may be
+ referenced by name from within other algorithms. Abstract operations are typically referenced using a functional application
+ style such as operationName(arg1, arg2). Some abstract
+ operations are treated as polymorphically dispatched methods of class-like specification abstractions. Such method-like
+ abstract operations are typically referenced using a method application style such as someValue.operationName(arg1, arg2).
+
+
Algorithms may be associated with productions of one of the ECMAScript grammars. A production that has multiple alternative
+ definitions will typically have a distinct algorithm for each alternative. When an algorithm is associated with a grammar
+ production, it may reference the terminal and nonterminal symbols of the production alternative as if they were parameters of
+ the algorithm. When used in this manner, nonterminal symbols refer to the actual alternative definition that is matched when
+ parsing the source text.
+
+
When an algorithm is associated with a production alternative, the alternative is typically shown without any “[
+ ]” grammar annotations. Such annotations should only affect the syntactic recognition of the alternative and have no
+ effect on the associated semantics for the alternative.
+
+
Unless explicitly specified otherwise, all chain productions have an implicit
+ definition for every algorithm that might be applied to that production’s left-hand side nonterminal. The implicit
+ definition simply reapplies the same algorithm name with the same parameters, if any, to the chain production’s sole right-hand side nonterminal and then returns the result.
+ For example, assume there is a production:
+
+
+
Block:
+
{StatementList}
+
+
+
but there is no corresponding Evaluation algorithm that is explicitly specified for that production. If in some algorithm
+ there is a statement of the form: “Return the result of evaluating
+ Block” it is implicit that an Evaluation algorithm exists of the form:
+
+
Runtime Semantics: Evaluation
+
+
Block:{StatementList}
+
+
Return the result of evaluating StatementList.
+
+
+
For clarity of expression, algorithm steps may be subdivided into sequential substeps. Substeps are indented and may
+ themselves be further divided into indented substeps. Outline numbering conventions are used to identify substeps with the
+ first level of substeps labelled with lower case alphabetic characters and the second level of substeps labelled with lower
+ case roman numerals. If more than three levels are required these rules repeat with the fourth level using numeric labels. For
+ example:
+
+
+
Top-level step
+
+
Substep.
+
Substep.
+
+
Subsubstep.
+
+
Subsubsubstep
+
+
Subsubsubsubstep
+
+
Subsubsubsubsubstep
+
+
+
+
+
+
+
+
+
+
+
+
+
A step or substep may be written as an “if” predicate that conditions its substeps. In this case, the substeps
+ are only applied if the predicate is true. If a step or substep begins with the word “else”, it is a predicate
+ that is the negation of the preceding “if” predicate step at the same level.
+
+
A step may specify the iterative application of its substeps.
+
+
A step that begins with “Assert:” asserts an invariant condition of its algorithm. Such assertions are used to
+ make explicit algorithmic invariants that would otherwise be implicit. Such assertions add no additional semantic requirements
+ and hence need not be checked by an implementation. They are used simply to clarify algorithms.
+
+
Mathematical operations such as addition, subtraction, negation, multiplication, division, and the mathematical functions
+ defined later in this clause should always be understood as computing exact mathematical results on mathematical real numbers,
+ which unless otherwise noted do not include infinities and do not include a negative zero that is distinguished from positive
+ zero. Algorithms in this standard that model floating-point arithmetic include explicit steps, where necessary, to handle
+ infinities and signed zero and to perform rounding. If a mathematical operation or function is applied to a floating-point
+ number, it should be understood as being applied to the exact mathematical value represented by that floating-point number;
+ such a floating-point number must be finite, and if it is +0 or −0
+ then the corresponding mathematical value is simply 0.
+
+
The mathematical function abs(x) produces the absolute value of
+ x, which is −x if x is negative (less
+ than zero) and otherwise is x itself.
+
+
The mathematical function sign(x) produces 1 if x is positive and −1 if x is negative. The sign function is not used in this standard for cases when x
+ is zero.
+
+
The mathematical function min(x1,x2, ..., xn) produces the mathematically
+ smallest of x1 through xn. The mathematical function max(x1,x2, ...,
+ xn) produces the mathematically largest of x1 through xn. The domain
+ and range of these mathematical functions include +∞ and −∞.
+
+
The notation “x modulo y” (y must be
+ finite and nonzero) computes a value k of the same sign as y (or zero) such that abs(k) < abs(y) and x−k = q×y for some integer q.
+
+
The mathematical function floor(x) produces the largest integer
+ (closest to positive infinity) that is not larger than x.
Context-free grammars are not sufficiently powerful to express all the rules that define whether a stream of input elements
+ form a valid ECMAScript Script or Module that may be evaluated. In some
+ situations additional rules are needed that may be expressed using either ECMAScript algorithm conventions or prose
+ requirements. Such rules are always associated with a production of a grammar and are called the static semantics of
+ the production.
+
+
Static Semantic Rules have names and typically are defined using an algorithm. Named Static Semantic Rules are associated
+ with grammar productions and a production that has multiple alternative definitions will typically have for each alternative a
+ distinct algorithm for each applicable named static semantic rule.
+
+
Unless otherwise specified every grammar production alternative in this specification implicitly has a definition for a
+ static semantic rule named Contains which takes an argument named
+ symbol whose value is a terminal or nonterminal of the grammar that includes the associated production. The default
+ definition of Contains is:
+
+
+
For each terminal and nonterminal grammar symbol, sym, in the definition of this production do
+
+
If sym is the same grammar symbol as symbol, return true.
+
If sym is a nonterminal, then
+
+
Let contained be the result of sym Contains symbol.
+
If contained is true, return true.
+
+
+
+
+
Return false.
+
+
+
The above definition is explicitly over-ridden for specific productions.
+
+
A special kind of static semantic rule is an Early Error Rule. Early error rules define early error conditions (see clause 16) that are associated with specific grammar productions.
+ Evaluation of most early error rules are not explicitly invoked within the algorithms of this specification. A conforming
+ implementation must, prior to the first evaluation of a Script, validate all of the early error rules
+ of the productions used to parse that Script. If any of the early error rules are violated the Script is invalid and cannot be evaluated.
Algorithms within this specification manipulate values each of which has an associated type. The possible value types are
+ exactly those defined in this clause. Types are further subclassified into ECMAScript language types and specification
+ types.
+
+
Within this specification, the notation “Type(x)” is
+ used as shorthand for “the type of x” where “type” refers to the ECMAScript language and specification types defined in
+ this clause. When the term “empty” is used as if it was naming a value, it is equivalent to saying “no value
+ of any type”.
An ECMAScript language type corresponds to values that are directly manipulated by an ECMAScript programmer using the
+ ECMAScript language. The ECMAScript language types are Undefined, Null, Boolean, String, Symbol, Number, and Object. An
+ ECMAScript language value is a value that is characterized by an ECMAScript language type.
The String type is the set of all finite ordered sequences of zero or more 16-bit unsigned integer values
+ (“elements”). The String type is generally used to represent textual data in a running ECMAScript program, in
+ which case each element in the String is treated as a UTF-16 code unit value. Each element is regarded as occupying a
+ position within the sequence. These positions are indexed with nonnegative integers. The first element (if any) is at index
+ 0, the next element (if any) at index 1, and so on. The length of a String is the number of elements (i.e., 16-bit values)
+ within it. The empty String has length zero and therefore contains no elements.
+
+
Where ECMAScript operations interpret String values, each element is interpreted as a single UTF-16 code unit. However,
+ ECMAScript does not place any restrictions or requirements on the sequence of code units in a String value, so they may be
+ ill-formed when interpreted as UTF-16 code unit sequences. Operations that do not interpret String contents treat them as
+ sequences of undifferentiated 16-bit unsigned integers. The function String.prototype.normalize (see
+ 21.1.3.12) can be used to explicitly normalize a string value. String.prototype.localeCompare (see 21.1.3.10) internally normalizes strings values, but no other operations
+ implicitly normalize the strings upon which they operate. Only operations that are explicitly specified to be language or
+ locale sensitive produce language-sensitive results.
+
+
+
NOTE The rationale behind this design was to keep the implementation of Strings as simple and
+ high-performing as possible. If ECMAScript source text is in Normalized Form C, string literals are guaranteed to also be
+ normalized, as long as they do not contain any Unicode escape sequences.
+
+
+
Some operations interpret String contents as UTF-16 encoded Unicode code points. In that case the interpretation is:
+
+
+
+
A code unit in the range 0 to 0xD7FF or in the range 0xE000 to 0xFFFF is interpreted as a code point with the same value.
+
+
+
+
A sequence of two code units, where the first code unit c1 is in the range 0xD800 to 0xDBFF and the second code unit
+ c2 is in the range 0xDC00 to 0xDFFF, is a surrogate pair and is interpreted as a code point with the value (c1 -
+ 0xD800) × 0x400 + (c2 – 0xDC00) + 0x10000. (See 10.1.2)
+
+
+
+
A code unit that is in the range 0xD800 to 0xDFFF, but is not part of a surrogate pair, is interpreted as a code point
+ with the same value.
Well-known symbols are built-in Symbol values that are explicitly referenced by algorithms of this specification. They
+ are typically used as the keys of properties whose values serve as extension points of a specification algorithm. Unless
+ otherwise specified, well-known symbols values are shared by all Code Realms (8.2).
+
+
Within this specification a well-known symbol is referred to by using a notation of the form @@name, where
+ “name” is one of the values listed in Table 1.
+
+
+ Table 1— Well-known Symbols
+
+
+
Specification Name
+
[[Description]]
+
Value and Purpose
+
+
+
@@hasInstance
+
"Symbol.hasInstance"
+
A method that determines if a constructor object recognizes an object as one of the constructor’s instances. Called by the semantics of the instanceof operator.
+
+
+
@@isConcatSpreadable
+
"Symbol.isConcatSpreadable"
+
A Boolean valued property that if true indicates that an object should be flattened to its array elements by Array.prototype.concat.
+
+
+
@@iterator
+
"Symbol.iterator"
+
A method that returns the default Iterator for an object. Called by the semantics of the for-of statement.
+
+
+
@@match
+
"Symbol.match"
+
A regular expression method that matches the regular expression against a string. Called by the String.prototype.match method.
+
+
+
@@replace
+
"Symbol.replace"
+
A regular expression method that replaces matched substrings of a string. Called by the String.prototype.replace method.
+
+
+
@@search
+
"Symbol.search"
+
A regular expression method that returns the index within a string that matches the regular expression. Called by the String.prototype.search method.
+
+
+
@@species
+
"Symbol.species"
+
A function valued property that is the constructor function that is used to create derived objects.
+
+
+
@@split
+
"Symbol.split"
+
A regular expression method that splits a string at the indices that match the regular expression. Called by the String.prototype.split method.
+
+
+
@@toPrimitive
+
"Symbol.toPrimitive"
+
A method that converts an object to a corresponding primitive value. Called by the ToPrimitive abstract operation.
+
+
+
@@toStringTag
+
"Symbol.toStringTag"
+
A String valued property that is used in the creation of the default string description of an object. Accessed by the built-in method Object.prototype.toString.
+
+
+
@@unscopables
+
"Symbol.unscopables"
+
An object valued property whose own property names are property names that are excluded from the with environment bindings of the associated object.
The Number type has exactly 18437736874454810627 (that is, 264−253+3) values, representing the double-precision
+ 64-bit format IEEE 754 values as specified in the IEEE Standard for Binary Floating-Point Arithmetic, except that the 9007199254740990 (that is, 253−2) distinct “Not-a-Number” values of the IEEE Standard are represented in
+ ECMAScript as a single special NaN value. (Note that the NaN value is produced by the program expression
+ NaN.) In some implementations, external code might be able to detect a difference between various Not-a-Number
+ values, but such behaviour is implementation-dependent; to ECMAScript code, all NaN values are indistinguishable from each
+ other.
+
+
+
NOTE The bit pattern that might be observed in an ArrayBuffer (see 24.1) after a Number value has been stored into it is not necessarily the same as
+ the internal representation of that Number value used by the ECMAScript implementation.
+
+
+
There are two other special values, called positive Infinity and negative Infinity. For brevity, these
+ values are also referred to for expository purposes by the symbols +∞ and −∞, respectively. (Note that these two infinite Number values are produced by the program
+ expressions +Infinity (or simply Infinity) and -Infinity.)
+
+
The other 18437736874454810624 (that is, 264−253) values are called the finite numbers. Half of these are
+ positive numbers and half are negative numbers; for every finite positive Number value there is a corresponding negative
+ value having the same magnitude.
+
+
Note that there is both a positive zero and a negative zero. For brevity, these values are also referred to
+ for expository purposes by the symbols +0 and −0, respectively.
+ (Note that these two different zero Number values are produced by the program expressions +0 (or simply
+ 0) and -0.)
+
+
The 18437736874454810622 (that is, 264−253−2) finite nonzero values are of two kinds:
+
+
18428729675200069632 (that is, 264−254) of them are normalized, having the form
+
+
s × m × 2e
+
+
where s is +1 or −1, m is a positive integer less than 253 but not less than 252, and
+ e is an integer ranging from −1074 to 971, inclusive.
+
+
The remaining 9007199254740990 (that is, 253−2) values are denormalized, having the form
+
+
s × m × 2e
+
+
where s is +1 or −1, m is a positive integer less than 252, and e is −1074.
+
+
Note that all the positive and negative integers whose magnitude is no greater than 253 are representable in the Number type (indeed, the integer 0 has two representations, +0 and -0).
+
+
A finite number has an odd significand if it is nonzero and the integer m used to express it (in one of
+ the two forms shown above) is odd. Otherwise, it has an even significand.
+
+
In this specification, the phrase “the Number value for
+ x” where x represents an exact nonzero real mathematical quantity (which might even be an
+ irrational number such as π) means a Number value chosen in the
+ following manner. Consider the set of all finite values of the Number type, with −0 removed
+ and with two additional values added to it that are not representable in the Number type, namely 21024 (which is +1 ×
+ 253× 2971) and −21024 (which is −1 × 253× 2971).
+ Choose the member of this set that is closest in value to x. If two values of the set are equally close, then the
+ one with an even significand is chosen; for this purpose, the two extra values 21024 and −21024 are considered
+ to have even significands. Finally, if 21024 was chosen,
+ replace it with +∞; if −21024 was chosen, replace it with −∞; if +0 was chosen, replace it with −0 if and only if x is less
+ than zero; any other chosen value is used unchanged. The result is the Number value for x. (This procedure
+ corresponds exactly to the behaviour of the IEEE 754 “round to nearest, ties to even” mode.)
+
+
Some ECMAScript operators deal only with integers in specific ranges such as −231 through 231−1,
+ inclusive, or in the range 0 through 216−1, inclusive. These operators accept any value of the Number type but first convert each
+ such value to an integer value in the expected range. See the descriptions of the numeric conversion operations in 7.1.
An accessor property associates a key value with one or two accessor functions, and a set of Boolean
+ attributes. The accessor functions are used to store or retrieve an ECMAScript language value that is associated with the property.
+
+
+
+
Properties are identified using key values. A property key value is either an ECMAScript String value or a Symbol
+ value. All String and Symbol values, including the empty string, are valid as property keys. A property name is a
+ property key that is a String value.
+
+
An integer index is a String-valued property key that is a canonical numeric String (see 7.1.16) and whose numeric value is either +0 or a positive integer ≤ 253−1. An array index is an integer index whose
+ numeric value i is in the range +0 ≤ i< 232−1.
+
+
Property keys are used to access properties and their values. There are two kinds of access for properties: get
+ and set, corresponding to value retrieval and assignment, respectively. The properties accessible via get and set
+ access includes both own properties that are a direct part of an object and inherited properties which are
+ provided by another associated object via a property inheritance relationship. Inherited properties may be either own or
+ inherited properties of the associated object. Each own property of an object must each have a key value that is distinct
+ from the key values of the other own properties of that object.
+
+
All objects are logically collections of properties, but there are multiple forms of objects that differ in their
+ semantics for accessing and manipulating their properties. Ordinary objects are the most common form of objects and
+ have the default object semantics. An exotic object is any form of object whose property semantics differ in any
+ way from the default semantics.
Attributes are used in this specification to define and explain the state of Object properties. A data property
+ associates a key value with the attributes listed in Table 2.
The value retrieved by a get access of the property.
+
+
+
[[Writable]]
+
Boolean
+
If false, attempts by ECMAScript code to change the property’s [[Value]] attribute using [[Set]] will not succeed.
+
+
+
[[Enumerable]]
+
Boolean
+
If true, the property will be enumerated by a for-in enumeration (see 13.6.4). Otherwise, the property is said to be non-enumerable.
+
+
+
[[Configurable]]
+
Boolean
+
If false, attempts to delete the property, change the property to be an accessor property, or change its attributes (other than [[Value]], or changing [[Writable]] to false) will fail.
+
+
+
+
+
An accessor property associates a key value with the attributes listed in Table 3.
+
+
+ Table 3 — Attributes of an Accessor Property
+
+
+
Attribute Name
+
Value Domain
+
Description
+
+
+
[[Get]]
+
Object or Undefined
+
If the value is an Object it must be a function Object. The function’s [[Call]] internal method (Table 6) is called with an empty arguments list to retrieve the property value each time a get access of the property is performed.
+
+
+
[[Set]]
+
Object or Undefined
+
If the value is an Object it must be a function Object. The function’s [[Call]] internal method (Table 6) is called with an arguments list containing the assigned value as its sole argument each time a set access of the property is performed. The effect of a property's [[Set]] internal method may, but is not required to, have an effect on the value returned by subsequent calls to the property's [[Get]] internal method.
+
+
+
[[Enumerable]]
+
Boolean
+
If true, the property is to be enumerated by a for-in enumeration (see 13.6.4). Otherwise, the property is said to be non-enumerable.
+
+
+
[[Configurable]]
+
Boolean
+
If false, attempts to delete the property, change the property to be a data property, or change its attributes will fail.
+
+
+
+
+
If the initial values of a property’s attributes are not explicitly specified by this specification, the default
+ value defined in Table 4 is used.
+
+
+ Table 4 — Default Attribute Values
+
+
+
Attribute Name
+
Default Value
+
+
+
[[Value]]
+
undefined
+
+
+
[[Get]]
+
undefined
+
+
+
[[Set]]
+
undefined
+
+
+
[[Writable]]
+
false
+
+
+
[[Enumerable]]
+
false
+
+
+
[[Configurable]]
+
false
+
+
+
+
+
+
+
6.1.7.2 Object Internal Methods and Internal Slots
+
+
The actual semantics of objects, in ECMAScript, are specified via algorithms called internal methods. Each
+ object in an ECMAScript engine is associated with a set of internal methods that defines its runtime behaviour. These
+ internal methods are not part of the ECMAScript language. They are defined by this specification purely for expository
+ purposes. However, each object within an implementation of ECMAScript must behave as specified by the internal methods
+ associated with it. The exact manner in which this is accomplished is determined by the implementation.
+
+
Internal method names are polymorphic. This means that different object values may perform different algorithms when a
+ common internal method name is invoked upon them. That actual object upon which an internal method is invoked is the
+ “target” of the invocation. If, at runtime, the implementation of an algorithm attempts to use an internal
+ method of an object that the object does not support, a TypeError exception is thrown.
+
+
Internal slots correspond to internal state that is associated with objects and used by various ECMAScript
+ specification algorithms. Internal slots are not object properties and they are not inherited. Depending upon the specific
+ internal slot specification, such state may consist of values of any ECMAScript
+ language type or of specific ECMAScript specification type values. Unless explicitly specified otherwise, internal
+ slots are allocated as part of the process of creating an object and may not be dynamically added to an object. Unless
+ specified otherwise, the initial value of an internal slot is the value undefined. Various
+ algorithms within this specification create objects that have internal slots. However, the ECMAScript language provides no
+ direct way to associate internal slots with an object.
+
+
Internal methods and internal slots are identified within this specification using names enclosed in double square
+ brackets [[ ]].
+
+
Table 5 summarizes the essential internal methods used by this specification that are
+ applicable to all objects created or manipulated by ECMAScript code. Every object must have algorithms for all of the
+ essential internal methods. However, all objects do not necessarily use the same algorithms for those methods.
+
+
The “Signature” column of Table 5 and other similar tables describes the invocation
+ pattern for each internal method. The invocation pattern always includes a parenthesized list of descriptive parameter
+ names. If a parameter name is the same as an ECMAScript type name then the name describes the required type of the
+ parameter value. If an internal method explicitly returns a value, its parameter list is followed by the symbol
+ “→” and the type name of the returned value. The type names used in signatures refer to the types defined
+ in clause 6 augmented by the following additional names.
+ “any” means the value may be any ECMAScript language type.
+ An internal method implicitly returns a Completion Record as
+ described in 6.2.2. In addition to its parameters, an internal
+ method always has access to the object that is the target of the method invocation.
+
+
+ Table 5 — Essential Internal Methods
+
+
+
Internal Method
+
Signature
+
Description
+
+
+
[[GetPrototypeOf]]
+
() → Object or Null
+
Determine the object that provides inherited properties for this object. A null value indicates that there are no inherited properties.
+
+
+
[[SetPrototypeOf]]
+
(Object or Null) → Boolean
+
Associate with this object another object that provides inherited properties. Passing null indicates that there are no inherited properties. Returns true indicating that the operation was completed successfully or false indicating that the operation was not successful.
+
+
+
[[IsExtensible]]
+
( ) → Boolean
+
Determine whether it is permitted to add additional properties to this object.
+
+
+
[[PreventExtensions]]
+
( ) → Boolean
+
Control whether new properties may be added to this object. Returns true if the operation was successful or false if the operation was unsuccessful.
Return a Property Descriptor for the own property of this object whose key is propertyKey, or undefined if no such property exists.
+
+
+
[[HasProperty]]
+
(propertyKey) → Boolean
+
Return a Boolean value indicating whether this object already has either an own or inherited property whose key is propertyKey.
+
+
+
[[Get]]
+
(propertyKey, Receiver) → any
+
Return the value of the property whose key is propertyKey from this object. If any ECMAScript code must be executed to retrieve the property value, Receiver is used as the this value when evaluating the code.
+
+
+
[[Set]]
+
(propertyKey,value, Receiver) → Boolean
+
Set the value of this object property whose key is propertyKey to value. If any ECMAScript code must be executed to set the property value, Receiver is used as the this value when evaluating the code. Returns true if that the property value was set or false if that it could not be set.
+
+
+
[[Delete]]
+
(propertyKey) → Boolean
+
Remove the own property whose key is propertyKey from this object . Return false if the property was not deleted and is still present. Return true if the property was deleted or is not present.
+
+
+
[[DefineOwnProperty]]
+
(propertyKey,PropertyDescriptor) → Boolean
+
Create or alter the own property, whose key is propertyKey, to have the state described by PropertyDescriptor. Return true if that the property was successfully created/updated or false if the property could not be created or updated.
+
+
+
[[Enumerate]]
+
()→Object
+
Return an iterator object that produces the keys of the string-keyed enumerable properties of the object.
Return a List whose elements are all of the own property keys for the object.
+
+
+
+
+
Table 6 summarizes additional essential internal methods that are supported by objects that may
+ be called as functions. A function object is an object that supports the [[Call]] internal methods. A
+ constructor (also referred to as a constructor function) is a function object that supports the
+ [[Construct]] internal method.
+
+
+ Table 6 — Additional Essential Internal Methods of Function Objects
+
Executes code associated with this object. Invoked via a function call expression. The arguments to the internal method are a this value and a list containing the arguments passed to the function by a call expression. Objects that implement this internal method are callable.
Creates an object. Invoked via the new or super operators. The first arguments to the internal method is a list containing the arguments of the operator. The second argument is the object to which the new operator was initially applied. Objects that implement this internal method are called constructors. A Function object is not necessarily a constructor and such non-constructor Function objects do not have a [[Construct]] internal method.
+
+
+
+
+
The semantics of the essential internal methods for ordinary objects and standard exotic objects are specified in clause 9. If any specified use of an internal method of an exotic
+ object is not supported by an implementation, that usage must throw a TypeError exception when attempted.
+
+
+
+
6.1.7.3 Invariants of the Essential Internal Methods
+
+
The Internal Methods of Objects of an ECMAScript engine must conform to the list of invariants specified below.
+ Ordinary ECMAScript Objects as well as all standard exotic objects in this specification maintain these invariants.
+ ECMAScript Proxy objects maintain these invariants by means of runtime checks on the result of traps invoked on the
+ [[ProxyHandler]] object.
+
+
Any implementation provided exotic objects must also maintain these invariants for those objects. Violation of these
+ invariants may cause ECMAScript code to have unpredictable behaviour and create security issues. However, violation of
+ these invariants must never compromise the memory safety of an implementation.
+
+
An implementation must not allow these invariants to be circumvented in any manner such as by providing alternative
+ interfaces that implement the functionality of the essential internal methods without enforcing their invariants.
+
+
Definitions:
+
+
● The target of an internal method is the object upon which the internal method is called.
+
+
● A target is non-extensible if it has been observed to return false from its [[IsExtensible]]
+ internal method, or true from its [[PreventExtensions]] internal method.
+
+
● A non-existent property is a property that does not exist as an own property on a non-extensible
+ target.
+
+
● All references to SameValue are according to the definition of SameValue algorithm specified in 7.2.9.
+
+
[[GetPrototypeOf]] ( )
+
+
● The Type of the return value must be either Object or Null.
+
+
● If target is non-extensible, and [[GetPrototypeOf]] returns a value v, then any future calls to
+ [[GetPrototypeOf]] should return the SameValue as v.
+
+
+
NOTE An object’s prototype chain should have finite length (that is, starting from any
+ object, recursively applying the [[GetPrototypeOf]] internal method to its result should eventually lead to the value
+ null). However, this requirement is not enforceable as an object level invariant if the prototype chain includes any
+ exotic objects that do not use the ordinary object definition of [[GetPrototypeOf]]. Such a circular prototype chain may
+ result in infinite loops when accessing object properties.
+
+
+
[[SetPrototypeOf]] (V)
+
+
● The Type of the return value must be Boolean.
+
+
● If target is non-extensible, [[SetPrototypeOf]] must return false, unless V is the SameValue as the target’s observed [[GetPrototypeOf]] value.
+
+
[[PreventExtensions]] ( )
+
+
● The Type of the return value must be Boolean.
+
+
● If [[PreventExtensions]] returns true, all future calls to [[IsExtensible]] on the target must return
+ false and the target is now considered non-extensible.
+
+
[[GetOwnProperty]] (P)
+
+
● The Type of the return value must be either Property Descriptor or Undefined.
● If a property P is described as a data property with Desc.[[Value]] equal to v and Desc.[[Writable]] and
+ Desc.[[Configurable]] are both false, then the SameValue must be returned for the
+ Desc.[[Value]] attribute of the property on all future calls to [[GetOwnProperty]] ( P ).
+
+
● If P’s attributes other than [[Writable]] may change over time or if the property might disappear,
+ then P’s [[Configurable]] attribute must be true.
+
+
● If the [[Writable]] attribute may change from false to true, then the [[Configurable]] attribute must be
+ true.
+
+
● If the target is non-extensible and P is non-existent, then all future calls to [[GetOwnProperty]] (P)
+ on the target must describe P as non-existent (i.e. [[GetOwnProperty]] (P) must return undefined).
+
+
+
NOTE As a consequence of the third invariant, if a property is described as a data property
+ and it may return different values over time, then either or both of the Desc.[[Writable]] and Desc.[[Configurable]]
+ attributes must be true even if no mechanism to change the value is exposed via the other internal methods.
+
+
+
[[DefineOwnProperty]] (P, Desc)
+
+
● The Type of the return value must be Boolean.
+
+
● [[DefineOwnProperty]] must return false if P has previously been observed as a non-configurable own
+ property of the target, unless either:
+
+
1. P is a non-configurable writable own data property. A non-configurable writable data property can be changed
+ into a non-configurable non-writable data property.
+
+
2. All attributes in Desc are the SameValue as P’s attributes.
+
+
● [[DefineOwnProperty]] (P, Desc) must return false if target is non-extensible and P is a non-existent own
+ property. That is, a non-extensible target object cannot be extended with new properties.
+
+
[[HasProperty]] ( P )
+
+
● The Type of the return value must be Boolean.
+
+
● If P was previously observed as a non-configurable data or accessor own property of the target,
+ [[HasProperty]] must return true.
+
+
[[Get]] (P, Receiver)
+
+
● If P was previously observed as a non-configurable, non-writable own data property of the target with
+ value v, then [[Get]] must return the SameValue.
+
+
● If P was previously observed as a non-configurable own accessor property of the target whose [[Get]]
+ attribute is undefined, the [[Get]] operation must return undefined.
+
+
[[Set]] ( P, V, Receiver)
+
+
● The Type of the return value must be Boolean.
+
+
● If P was previously observed as a non-configurable, non-writable own data property of the target, then
+ [[Set]] must return false unless V is the SameValue as P’s [[Value]] attribute.
+
+
● If P was previously observed as a non-configurable own accessor property of the target whose [[Set]]
+ attribute is undefined, the [[Set]] operation must return false.
+
+
[[Delete]] ( P )
+
+
● The Type of the return value must be Boolean.
+
+
● If P was previously observed to be a non-configurable own data or accessor property of the target,
+ [[Delete]] must return false.
● The Type of each element of the returned List is
+ either String or Symbol.
+
+
● The returned List must contain at least the keys of
+ all non-configurable own properties that have previously been observed.
+
+
● If the object is non-extensible, the returned List
+ must contain only the keys of all own properties of the object that are observable using [[GetOwnProperty]].
Well-known intrinsics are built-in objects that are explicitly referenced by the algorithms of this specification and
+ which usually have Realm specific identities. Unless otherwise specified each intrinsic
+ object actually corresponds to a set of similar objects, one per Realm.
+
+
Within this specification a reference such as %name% means the intrinsic object, associated with the current Realm, corresponding to the name. Determination of the current Realm and its intrinsics is described in 8.1.2.5. The well-known intrinsics are listed in Table 7.
A specification type corresponds to meta-values that are used within algorithms to describe the semantics of ECMAScript
+ language constructs and ECMAScript language types. The specification types are Reference, List, Completion, Property Descriptor, Lexical
+ Environment, Environment Record, and Data Block.
+ Specification type values are specification artefacts that do not necessarily correspond to any specific entity within an
+ ECMAScript implementation. Specification type values may be used to describe intermediate results of ECMAScript expression
+ evaluation but such values cannot be stored as properties of objects or values of ECMAScript language variables.
The List type is used to explain the evaluation of argument lists (see 12.3.6) in
+ new expressions, in function calls, and in other algorithms where a simple ordered list of values is needed.
+ Values of the List type are simply ordered sequences of list elements containing the individual values. These sequences may
+ be of any length. The elements of a list may be randomly accessed using 0-origin indices. For notational convenience an
+ array-like syntax can be used to access List elements. For example, arguments[2] is shorthand for saying the
+ 3rd element of the List arguments.
+
+
For notational convenience within this specification, a literal syntax can be used to express a new List value. For
+ example, «1, 2» defines a List value that has two elements each of which is initialized to a specific value. A
+ new empty List can be expressed as «».
+
+
The Record type is used to describe data aggregations within the algorithms of this specification. A Record type value
+ consists of one or more named fields. The value of each field is either an ECMAScript value or an abstract value represented
+ by a name associated with the Record type. Field names are always enclosed in double brackets, for example [[value]].
+
+
For notational convenience within this specification, an object literal-like syntax can be used to express a Record
+ value. For example, {[[field1]]: 42, [[field2]]: false, [[field3]]: empty} defines a Record value that has
+ three fields, each of which is initialized to a specific value. Field name order is not significant. Any fields that are not
+ explicitly listed are considered to be absent.
+
+
In specification text and algorithms, dot notation may be used to refer to a specific field of a Record value. For
+ example, if R is the record shown in the previous paragraph then R.[[field2]] is shorthand for “the field of R named
+ [[field2]]”.
+
+
Schema for commonly used Record field combinations may be named, and that name may be used as a prefix to a literal
+ Record value to identify the specific kind of aggregations that is being described. For example:
+ PropertyDescriptor{[[Value]]: 42, [[Writable]]: false, [[Configurable]]: true}.
The Completion type is a Record used to explain the runtime propagation of values and control flow such as the
+ behaviour of statements (break, continue, return and throw) that
+ perform nonlocal transfers of control.
+
+
Values of the Completion type are Record values whose fields are defined as by Table 8.
The algorithms of this specification often implicitly return Completion Records whose [[type]] is normal. Unless it is
+ otherwise obvious from the context, an algorithm statement that returns a value that is not a Completion Record, such as:
However, if the value expression of a “return” statement
+ is a Completion Record construction literal, the resulting Completion Record is returned. If the value expression is a call to
+ an abstract operation, the “return” statement simply returns
+ the Completion Record produced by the abstract operation.
+
+
The abstract operation Completion(completionRecord) is used to emphasize that
+ a previously computed Completion Record is being returned. The Completion abstract operation takes a single argument,
+ completionRecord, and performs the following steps: such as
NOTE The Reference type is used to explain the behaviour of such operators as
+ delete, typeof, the assignment operators, the super keyword and other language
+ features. For example, the left-hand operand of an assignment is expected to produce a reference.
+
+
+
A Reference is a resolved name or property binding. A Reference consists of three components, the
+ base value, the referenced name and the Boolean valued strict reference flag. The
+ base value is either undefined, an Object, a Boolean, a String, a Symbol, a Number, or an Environment Record (8.1.1). A base
+ value of undefined indicates that the Reference could not be resolved to a binding. The referenced name
+ is a String or Symbol value.
+
+
A Super Reference is a Reference that is used to represents a name binding that was expressed using the super keyword.
+ A Super Reference has an additional thisValue component and its base value will never be an Environment Record.
+
+
The following abstract operations are used in this specification to access the components of references:
+
+
+
+
GetBase(V). Returns the base value component of the reference V.
+
+
+
+
GetReferencedName(V). Returns the referenced name component of the reference V.
+
+
+
+
IsStrictReference(V). Returns the strict reference flag component of the reference V.
+
+
+
+
HasPrimitiveBase(V). Returns true if Type(base)
+ is Boolean, String, Symbol, or Number.
+
+
+
+
IsPropertyReference(V). Returns true if either the base value is an object or HasPrimitiveBase(V) is
+ true; otherwise returns false.
+
+
+
+
IsUnresolvableReference(V). Returns true if the base value is undefined and false
+ otherwise.
+
+
+
+
IsSuperReference(V). Returns true if this reference has a thisValue component.
+
+
+
+
The following abstract operations are used in this specification to operate on references:
NOTE The object that may be created in step 5.a.ii is not accessible outside of the above
+ abstract operation and the ordinary object [[Get]] internal method. An implementation might choose to avoid the actual
+ creation of the object.
NOTE The object that may be created in step 6.a.ii is not accessible outside of the above
+ algorithm and the ordinary object [[Set]] internal method. An implementation might choose to avoid the actual creation
+ of that object.
The Property Descriptor type is used to explain the manipulation and reification of Object property attributes. Values
+ of the Property Descriptor type are Records. Each field’s name is an attribute name and its value is a corresponding
+ attribute value as specified in 6.1.7.1. In addition, any field may be present or
+ absent. The schema name used within this specification to tag literal descriptions of Property Descriptor records is
+ “PropertyDescriptor”.
+
+
Property Descriptor values may be further classified as data Property Descriptors and accessor Property Descriptors
+ based upon the existence or use of certain fields. A data Property Descriptor is one that includes any fields named either
+ [[Value]] or [[Writable]]. An accessor Property Descriptor is one that includes any fields named either [[Get]] or
+ [[Set]]. Any Property Descriptor may have fields named [[Enumerable]] and [[Configurable]]. A Property Descriptor value
+ may not be both a data Property Descriptor and an accessor Property Descriptor; however, it may be neither. A generic
+ Property Descriptor is a Property Descriptor value that is neither a data Property Descriptor nor an accessor Property
+ Descriptor. A fully populated Property Descriptor is one that is either an accessor Property Descriptor or a data Property
+ Descriptor and that has all of the fields that correspond to the property attributes defined in either Table 2 or Table 3.
+
+
The following abstract operations are used in this specification to operate upon Property Descriptor values:
If Desc does not have a [[Value]] field, set Desc.[[Value]] to like.[[Value]].
+
If Desc does not have a [[Writable]] field, set Desc.[[Writable]] to
+ like.[[Writable]].
+
+
+
Else,
+
+
If Desc does not have a [[Get]] field, set Desc.[[Get]] to like.[[Get]].
+
If Desc does not have a [[Set]] field, set Desc.[[Set]] to like.[[Set]].
+
+
+
If Desc does not have an [[Enumerable]] field, set Desc.[[Enumerable]] to
+ like.[[Enumerable]].
+
If Desc does not have a [[Configurable]] field, set Desc.[[Configurable]] to
+ like.[[Configurable]].
+
Return Desc.
+
+
+
+
+
+
6.2.5 The Lexical Environment and Environment Record Specification Types
+
+
The Lexical Environment and Environment
+ Record types are used to explain the behaviour of name resolution in nested functions and blocks. These types and the
+ operations upon them are defined in 8.1.
The Data Block specification type is used to describe a distinct and mutable sequence of byte-sized (8 bit) numeric
+ values. A Data Block value is created with a fixed number of bytes that each have the initial value 0.
+
+
For notational convenience within this specification, an array-like syntax can be used to express to the individual
+ bytes of a Data Block value. This notation presents a Data Block value as a 0-origined integer indexed sequence of bytes.
+ For example, if db is a 5 byte Data Block value then db[2] can be used to express access to its
+ 3rd byte.
+
+
The following abstract operations are used in this specification to operate upon Data Block values:
These operations are not a part of the ECMAScript language; they are defined here to solely to aid the specification of the
+ semantics of the ECMAScript language. Other, more specialized abstract operations are defined throughout this
+ specification.
The ECMAScript language implicitly performs automatic type conversion as needed. To clarify the semantics of certain
+ constructs it is useful to define a set of conversion abstract operations. The conversion abstract operations are
+ polymorphic; they can accept a value of any ECMAScript language type or of a Completion Record value. But no other specification types are used with
+ these operations.
The abstract operation ToPrimitive takes an input argument and an optional argument PreferredType. The abstract operation ToPrimitive converts its input argument to a non-Object
+ type. If an object is capable of converting to more than one primitive type, it may use the optional hint PreferredType to favour that type. Conversion occurs according to Table 9:
NOTE When ToPrimitive is called with no hint, then it generally behaves as if the hint were
+ Number. However, objects may over-ride this behaviour by defining a @@toPrimitive method. Of the objects defined in this
+ specification only Date objects (see 20.3.4.45) and Symbol objects (see 19.4.3.4) over-ride the default ToPrimitive behaviour. Date objects
+ treat no hint as if the hint were String.
ToNumber applied to Strings applies the following grammar to the input String interpreted
+ as a sequence of UTF-16 encoded code points (6.1.4). If the
+ grammar cannot interpret the String as an expansion of StringNumericLiteral, then the result of
+ ToNumber is NaN.
+
+
+
NOTE The terminal symbols of this grammar are all composed of Unicode BMP code points so
+ the result will be NaN if the string contains the UTF-16 encoding of any supplementary code points or any
+ unpaired surrogate code points
+
+
+
Syntax
+
+
+
StringNumericLiteral:::
+
StrWhiteSpaceopt
+
StrWhiteSpaceoptStrNumericLiteralStrWhiteSpaceopt
+
+
+
+
StrWhiteSpace:::
+
StrWhiteSpaceCharStrWhiteSpaceopt
+
+
+
+
StrWhiteSpaceChar:::
+
WhiteSpace
+
LineTerminator
+
+
+
+
StrNumericLiteral:::
+
StrDecimalLiteral
+
BinaryIntegerLiteral
+
OctalIntegerLiteral
+
HexIntegerLiteral
+
+
+
+
StrDecimalLiteral:::
+
StrUnsignedDecimalLiteral
+
+StrUnsignedDecimalLiteral
+
-StrUnsignedDecimalLiteral
+
+
+
+
StrUnsignedDecimalLiteral:::
+
Infinity
+
DecimalDigits.DecimalDigitsoptExponentPartopt
+
.DecimalDigitsExponentPartopt
+
DecimalDigitsExponentPartopt
+
+
+
+
DecimalDigits:::
+
DecimalDigit
+
DecimalDigitsDecimalDigit
+
+
+
+
DecimalDigit:::one of
+
0123456789
+
+
+
+
ExponentPart:::
+
ExponentIndicatorSignedInteger
+
+
+
+
ExponentIndicator:::one of
+
eE
+
+
+
+
SignedInteger:::
+
DecimalDigits
+
+DecimalDigits
+
-DecimalDigits
+
+
+
All grammar symbols not explicitly defined above have the definitions used in the Lexical Grammar for numeric
+ literals (11.8.3)
+
+
+
NOTE Some differences should be noted between the syntax of a StringNumericLiteral
+ and a NumericLiteral (see 11.8.3):
+
+
+
+
A StringNumericLiteral may include leading and/or trailing white space and/or line terminators.
+
+
+
+
A StringNumericLiteral that is decimal may have any number of leading 0 digits.
+
+
+
+
A StringNumericLiteral that is decimal may include a + or - to indicate its
+ sign.
+
+
+
+
A StringNumericLiteral that is empty or contains only white space is converted to +0.
+
+
+
+
Infinityand –Infinity are recognized as a StringNumericLiteral but not
+ as a NumericLiteral.
The conversion of a String to a Number value is similar overall to the determination of the Number value for a
+ numeric literal (see 11.8.3), but some of the details are different, so the
+ process for converting a String numeric literal to a value of Number type is given here. This value is determined in two
+ steps: first, a mathematical value (MV) is derived from the String numeric literal; second, this mathematical value is
+ rounded as described below. The MV on any grammar symbol, not provided below, is the MV for that symbol defined in 11.8.3.1.
+
+
+
+
The MV of StringNumericLiteral:::[empty] is 0.
+
+
+
+
The MV of StringNumericLiteral:::StrWhiteSpace is 0.
+
+
+
+
The MV of StringNumericLiteral:::StrWhiteSpaceoptStrNumericLiteralStrWhiteSpaceopt is the MV of StrNumericLiteral, no matter whether white space is present or not.
+
+
+
+
The MV of StrNumericLiteral:::StrDecimalLiteral is the MV of StrDecimalLiteral.
+
+
+
+
The MV of StrNumericLiteral:::BinaryIntegerLiteral is the MV of BinaryIntegerLiteral.
+
+
+
+
The MV of StrNumericLiteral:::OctalIntegerLiteral is the MV of OctalIntegerLiteral.
+
+
+
+
The MV of StrNumericLiteral:::HexIntegerLiteral is the MV of HexIntegerLiteral.
+
+
+
+
The MV of StrDecimalLiteral:::StrUnsignedDecimalLiteral is the MV of StrUnsignedDecimalLiteral.
+
+
+
+
The MV of StrDecimalLiteral:::+StrUnsignedDecimalLiteral is the MV of StrUnsignedDecimalLiteral.
+
+
+
+
The MV of StrDecimalLiteral:::-StrUnsignedDecimalLiteral is the negative of the MV of StrUnsignedDecimalLiteral. (Note that if the MV of StrUnsignedDecimalLiteral is 0, the negative of this MV is also 0. The rounding rule described
+ below handles the conversion of this signless mathematical zero to a floating-point +0 or −0 as
+ appropriate.)
+
+
+
+
The MV of StrUnsignedDecimalLiteral:::Infinity is 1010000 (a value
+ so large that it will round to +∞).
+
+
+
+
The MV of StrUnsignedDecimalLiteral:::DecimalDigits. is the MV of DecimalDigits.
+
+
+
+
The MV of StrUnsignedDecimalLiteral:::DecimalDigits.DecimalDigits is the MV of
+ the first DecimalDigits plus (the MV of the second DecimalDigits
+ times 10−n), where n is the
+ number of code points in the second DecimalDigits.
+
+
+
+
The MV of StrUnsignedDecimalLiteral:::DecimalDigits.ExponentPart is the MV of
+ DecimalDigits times 10e, where e is the MV of ExponentPart.
+
+
+
+
The MV of StrUnsignedDecimalLiteral:::DecimalDigits.DecimalDigitsExponentPart is (the MV of the first DecimalDigits plus (the MV of the second
+ DecimalDigits times 10−n)) times 10e, where n is the number
+ of code points in the second DecimalDigits and e is the MV of ExponentPart.
+
+
+
+
The MV of StrUnsignedDecimalLiteral:::.DecimalDigits is the MV of DecimalDigits times
+ 10−n, where n is the number of code points in DecimalDigits.
+
+
+
+
The MV of StrUnsignedDecimalLiteral:::.DecimalDigitsExponentPart is the MV of
+ DecimalDigits times 10e−n, where n is the number of code points in
+ DecimalDigits and e is the MV of ExponentPart.
+
+
+
+
The MV of StrUnsignedDecimalLiteral:::DecimalDigits is the MV of DecimalDigits.
+
+
+
+
The MV of StrUnsignedDecimalLiteral:::DecimalDigitsExponentPart is the MV of DecimalDigits times
+ 10e, where e is the MV of ExponentPart.
+
+
+
+
Once the exact MV for a String numeric literal has been determined, it is then rounded to a value of the Number type.
+ If the MV is 0, then the rounded value is +0 unless the first non white space code point in the String numeric literal
+ is ‘-’, in which case the rounded value is −0. Otherwise, the rounded value must be the
+ Number value for the MV (in the sense defined in 6.1.6), unless
+ the literal includes a StrUnsignedDecimalLiteral and the literal has more than 20 significant
+ digits, in which case the Number value may be either the Number value for the MV of a literal produced by replacing each
+ significant digit after the 20th with a 0 digit or the Number value for the MV of a literal produced by replacing each
+ significant digit after the 20th with a 0 digit and then incrementing the literal at the 20th digit position. A digit is
+ significant if it is not part of an ExponentPart and
+
+
+
it is not 0; or
+
there is a nonzero digit to its left and there is a nonzero digit, not in the ExponentPart, to its right.
The abstract operation ToInt32 converts argument to one of 232 integer values in the range −231 through 231−1,
+ inclusive. This abstract operation functions as follows:
The abstract operation ToUint32 converts argument to one of 232 integer values in the range 0 through 232−1, inclusive. This abstract operation functions as
+ follows:
The abstract operation ToInt16 converts argument to one of 216 integer values in the range −32768
+ through 32767, inclusive. This abstract operation functions as
+ follows:
The abstract operation ToUint16 converts argument to one of 216 integer values in the range 0 through 216−1, inclusive. This abstract operation functions as
+ follows:
The abstract operation ToInt8 converts argument to one of 28 integer values in the range −128 through
+ 127, inclusive. This abstract operation functions as follows:
The abstract operation ToUint8 converts argument to one of 28 integer values in the range 0 through 255, inclusive. This abstract operation functions as follows:
The abstract operation ToUint8Clamp converts argument to one of 28 integer values in the range 0 through 255, inclusive. This abstract operation functions as follows:
NOTE Note that unlike the other ECMAScript integer conversion abstract operation, ToUint8Clamp
+ rounds rather than truncates non-integer values and does not convert +∞ to 0. ToUint8Clamp does “round
+ half to even” tie-breaking. This differs from Math.round which does
+ “round half up” tie-breaking.
The abstract operation ToString converts a Number m to String format as
+ follows:
+
+
+
If m is NaN, return the String "NaN".
+
If m is +0 or −0, return the String "0".
+
If m is less than zero, return the String concatenation of the String "-" and ToString(−m).
+
If m is +∞, return the String "Infinity".
+
Otherwise, let n, k, and s be integers such that k ≥ 1, 10k−1
+ ≤ s < 10k, the Number value for s × 10n−k is
+ m, and k is as small as possible. Note that k is the number of digits in the decimal
+ representation of s, that s is not divisible by 10, and that the least significant digit of s
+ is not necessarily uniquely determined by these criteria.
+
If k ≤ n ≤ 21, return the String consisting of the code units of the k digits of the
+ decimal representation of s (in order, with no leading zeroes), followed by n−k occurrences of
+ the code unit 0x0030 (DIGIT ZERO).
+
If 0 < n ≤ 21, return the String consisting of the code units of the most significant n digits
+ of the decimal representation of s, followed by the code unit 0x002E (FULL STOP), followed by the code units
+ of the remaining k−n digits of the decimal representation of s.
+
If −6 < n ≤ 0, return the String consisting of the code unit 0x0030 (DIGIT ZERO), followed by the
+ code unit 0x002E (FULL STOP), followed by −n occurrences of the code unit 0x0030 (DIGIT ZERO), followed
+ by the code units of the k digits of the decimal representation of s.
+
Otherwise, if k = 1, return the String consisting of the code unit of the single digit of s, followed
+ by code unit 0x0065 (LATIN SMALL LETTER E), followed by the code unit 0x002B (PLUS SIGN) or the code unit 0x002D
+ (HYPHEN-MINUS) according to whether n−1 is positive or negative, followed by the code units of the
+ decimal representation of the integer abs(n−1) (with no
+ leading zeroes).
+
Return the String consisting of the code units of the most significant digit of the decimal representation of
+ s, followed by code unit 0x002E (FULL STOP), followed by the code units of the remaining k−1
+ digits of the decimal representation of s, followed by code unit 0x0065 (LATIN SMALL LETTER E), followed by
+ code unit 0x002B (PLUS SIGN) or the code unit 0x002D (HYPHEN-MINUS) according to whether n−1 is
+ positive or negative, followed by the code units of the decimal representation of the integer abs(n−1) (with no leading zeroes).
+
+
+
+
NOTE 1 The following observations may be useful as guidelines for implementations, but are
+ not part of the normative requirements of this Standard:
+
+
+
+
If x is any Number value other than −0, then ToNumber(ToString(x)) is exactly the same Number value as x.
+
+
+
+
The least significant digit of s is not always uniquely determined by the requirements listed in step 5.
+
+
+
+
+
+
NOTE 2 For implementations that provide more accurate conversions than required by the rules
+ above, it is recommended that the following alternative version of step 5 be used as a guideline:
+
+
Otherwise, let n, k, and s be integers such that k ≥ 1, 10k−1
+ ≤ s < 10k, the Number value for s × 10n−k is
+ m, and k is as small as possible. If there are multiple possibilities for s, choose the value of
+ s for which s × 10n−k is closest in value to m. If there are
+ two such possible values of s, choose the one that is even. Note that k is the number of digits in the
+ decimal representation of s and that s is not divisible by 10.
+
+
+
+
NOTE 3 Implementers of ECMAScript may find useful the paper and code written by David M. Gay
+ for binary-to-decimal conversion of floating-point numbers:
The abstract operation ToLength converts argument to an integer suitable for use as the length of an
+ array-like object. It performs the following steps:
The abstract operation CanonicalNumericIndexString returns argument converted to a numeric value if it is a
+ String representation of a Number that would be produced by ToString, or the string
+ "-0". Otherwise, it returns undefined. This abstract operation functions as
+ follows:
The abstract operation RequireObjectCoercible throws an error if argument is a value that cannot be converted
+ to an Object using ToObject. It is defined by Table 14:
The abstract operation IsCallable determines if argument, which must be an ECMAScript language value or a Completion Record, is a callable function with a [[Call]] internal
+ method.
The abstract operation IsConstructor determines if argument, which must be an ECMAScript language value or a Completion Record, is a function object with a [[Construct]] internal
+ method.
The abstract operation IsExtensible is used to determine whether
+ additional properties can be added to the object that is O. A Boolean value is returned. This abstract operation
+ performs the following steps:
The internal comparison abstract operation SameValue(x, y), where x and y are
+ ECMAScript language values, produces true or false. Such a
+ comparison is performed as follows:
If x and y are exactly the same sequence of code units (same length and same code units at
+ corresponding indices) return true; otherwise, return false.
The internal comparison abstract operation SameValueZero(x, y), where x and y
+ are ECMAScript language values, produces true or false. Such a
+ comparison is performed as follows:
If x and y are exactly the same sequence of code units (same length and same code units at
+ corresponding indices) return true; otherwise, return false.
The comparison x < y, where x and y are values, produces true,
+ false, or undefined (which indicates that at least one operand is NaN). In addition to x and
+ y the algorithm takes a Boolean flag named LeftFirst as a parameter. The flag is used to
+ control the order in which operations with potentially visible side-effects are performed upon x and
+ y. It is necessary because ECMAScript specifies left to right evaluation of expressions. The default value of
+ LeftFirst is true and indicates that the x parameter corresponds to an expression
+ that occurs to the left of the y parameter’s corresponding expression. If LeftFirst
+ is false, the reverse is the case and operations must be performed upon y before x. Such a
+ comparison is performed as follows:
If py is a prefix of px, return false. (A String value p is a prefix of String value
+ q if q can be the result of concatenating p and some other String r. Note that any
+ String is a prefix of itself, because r may be the empty String.)
+
If px is a prefix of py, return true.
+
Let k be the smallest nonnegative integer such that the code unit at index k within px is
+ different from the code unit at index k within py. (There must be such a k, for neither
+ String is a prefix of the other.)
+
Let m be the integer that is the code unit value at index k within px.
+
Let n be the integer that is the code unit value at index k within py.
+
If m < n, return true. Otherwise, return false.
+
+
+
Else,
+
+
Let nx be ToNumber(px). Because px and py are primitive
+ values evaluation order is not important.
If nx and ny are the same Number value, return false.
+
If nx is +0 and ny is −0, return false.
+
If nx is −0 and ny is +0, return false.
+
If nx is +∞, return false.
+
If ny is +∞, return true.
+
If ny is −∞, return false.
+
If nx is −∞, return true.
+
If the mathematical value of nx is less than the mathematical value of ny —note that these
+ mathematical values are both finite and not both zero—return true. Otherwise, return
+ false.
+
+
+
+
+
+
NOTE 1 Step 5 differs from step 11 in the algorithm for the addition operator +
+ (12.7.3) in using “and” instead of “or”.
+
+
+
+
NOTE 2 The comparison of Strings uses a simple lexicographic ordering on sequences of code unit
+ values. There is no attempt to use the more complex, semantically oriented definitions of character or string equality and
+ collating order defined in the Unicode specification. Therefore String values that are canonically equal according to the
+ Unicode standard could test as unequal. In effect this algorithm assumes that both Strings are already in normalized form.
+ Also, note that for strings containing supplementary characters, lexicographic ordering on sequences of UTF-16 code unit
+ values differs from that on sequences of code point values.
The abstract operation Get is used to retrieve the value of a specific
+ property of an object. The operation is called with arguments O and P where O is the
+ object and P is the property key. This abstract operation performs the following
+ steps:
The abstract operation GetV is used to retrieve the value of a specific property of an ECMAScript language value. If the value is not an object, the property lookup is
+ performed using a wrapper object appropriate for the type of the value. The operation is called with arguments V
+ and P where V is the value and P is the property key. This
+ abstract operation performs the following steps:
The abstract operation Set is used to set the value of a specific
+ property of an object. The operation is called with arguments O, P, V, and Throw where O is the object, P is the property key,
+ V is the new value for the property and Throw is a Boolean flag. This abstract operation
+ performs the following steps:
The abstract operation CreateDataProperty is used to create a new own
+ property of an object. The operation is called with arguments O, P, and V where
+ O is the object, P is the property key, and V is the value
+ for the property. This abstract operation performs the following steps:
Let newDesc be the PropertyDescriptor{[[Value]]: V, [[Writable]]: true, [[Enumerable]]:
+ true, [[Configurable]]: true}.
+
Return O.[[DefineOwnProperty]](P, newDesc).
+
+
+
+
NOTE This abstract operation creates a property whose attributes are set to the same defaults
+ used for properties created by the ECMAScript language assignment operator. Normally, the property will not already exist.
+ If it does exist and is not configurable or if O is not extensible, [[DefineOwnProperty]] will return
+ false.
The abstract operation CreateMethodProperty is used to create a new own
+ property of an object. The operation is called with arguments O, P, and V where
+ O is the object, P is the property key, and V is the value
+ for the property. This abstract operation performs the following steps:
Let newDesc be the PropertyDescriptor{[[Value]]: V, [[Writable]]: true, [[Enumerable]]:
+ false, [[Configurable]]: true}.
+
Return O.[[DefineOwnProperty]](P, newDesc).
+
+
+
+
NOTE This abstract operation creates a property whose attributes are set to the same defaults
+ used for built-in methods and methods defined using class declaration syntax. Normally, the property will not already
+ exist. If it does exist and is not configurable or if O is not extensible, [[DefineOwnProperty]] will return
+ false.
The abstract operation CreateDataPropertyOrThrow is used to create a
+ new own property of an object. It throws a TypeError exception if the requested property update
+ cannot be performed. The operation is called with arguments O, P, and V where O
+ is the object, P is the property key, and V is the value for the
+ property. This abstract operation performs the following steps:
NOTE This abstract operation creates a property whose attributes are set to the same defaults
+ used for properties created by the ECMAScript language assignment operator. Normally, the property will not already exist.
+ If it does exist and is not configurable or if O is not extensible, [[DefineOwnProperty]] will return false
+ causing this operation to throw aTypeErrorexception.
The abstract operation DefinePropertyOrThrow is used to call the
+ [[DefineOwnProperty]] internal method of an object in a manner that will throw a TypeError exception if the requested
+ property update cannot be performed. The operation is called with arguments O, P, and desc
+ where O is the object, P is the property key, and desc is
+ the Property Descriptor for the property. This abstract operation
+ performs the following steps:
The abstract operation DeletePropertyOrThrow is used to remove a specific own property of an object. It throws an
+ exception if the property is not configurable. The operation is called with arguments O and P where
+ O is the object and P is the property key. This abstract operation
+ performs the following steps:
The abstract operation GetMethod is used to get the value of a specific property of an object when the value of the
+ property is expected to be a function. The operation is called with arguments O and P where
+ O is the object, P is the property key. This abstract operation
+ performs the following steps:
The abstract operation HasProperty is used to determine whether an object has a property with the specified property key. The property may be either an own or inherited. A Boolean value is returned. The
+ operation is called with arguments O and P where O is the object and P is the
+ property key. This abstract operation performs the following steps:
The abstract operation HasOwnProperty is used to determine whether an object has an own property with the specified property key. A Boolean value is returned. The operation is called with arguments O
+ and P where O is the object and P is the property key. This
+ abstract operation performs the following steps:
The abstract operation Call is used to call the [[Call]] internal method of a function object. The operation is called
+ with arguments F, V , and optionally argumentsList where F is the function
+ object, V is an ECMAScript language value that is the this
+ value of the [[Call]], and argumentsList is the value passed to the corresponding argument of the internal
+ method. If argumentsList is not present, an empty List is
+ used as its value. This abstract operation performs the following steps:
The abstract operation Invoke is used to call a method property of an
+ object. The operation is called with arguments O, P , and optionally argumentsList where
+ O serves as both the lookup point for the property and the this value of the call, P is the property key, and argumentsList is the list of arguments values passed to the method.
+ If argumentsList is not present, an empty List is used as
+ its value. This abstract operation performs the following steps:
The abstract operation Construct is used to call the [[Construct]] internal method of a function object. The operation is
+ called with arguments F, and optionally argumentsList, and
+ newTarget where F is the function object. argumentsList and newTarget are the
+ values to be passed as the corresponding arguments of the internal method. If argumentsList is not present, an
+ empty List is used as its value. If newTarget is not
+ present, F is used as its value. This abstract operation performs the following steps:
+
+
+
If newTarget was not passed, let newTarget be F.
+
If argumentsList was not passed, let argumentsList be a new empty List.
The abstract operation SetIntegrityLevel is used to fix the set of own
+ properties of an object. This abstract operation performs the following steps:
The abstract operation TestIntegrityLevel is used to determine if the
+ set of own properties of an object are fixed. This abstract operation performs the following steps:
The abstract operation CreateArrayFromList is used to create an Array
+ object whose elements are provided by a List. This abstract operation
+ performs the following steps:
The abstract operation CreateListFromArrayLike is used to create a List value whose elements are provided by the indexed
+ properties of an array-like object, obj. The optional argument elementTypes is a List containing the names of ECMAScript Language Types that are allowed
+ for element values of the List that is created. This abstract
+ operation performs the following steps:
The abstract operation OrdinaryHasInstance implements the default
+ algorithm for determining if an object O inherits from the instance object inheritance path provided by
+ constructor C. This abstract operation performs the following steps:
7.3.20
+ SpeciesConstructor ( O, defaultConstructor )
+
+
The abstract operation SpeciesConstructor is used to retrieve the constructor that should be used to create new objects
+ that are derived from the argument object O. The defaultConstructor argument is the constructor to use
+ if a constructor @@species property cannot be found starting from O. This abstract operation performs the
+ following steps:
If desc.[[Enumerable]] is true, append key to names.
+
+
+
+
+
+
+
Order the elements of names so they are in the same relative order as would be produced by the Iterator that
+ would be returned if the [[Enumerate]] internal method was invoked on O.
+
Return names.
+
+
+
+
NOTE The order of elements is returned list is the same as the enumeration order that used by a
+ for-in statement.
The abstract operation IteratorStep with argument iterator requests the next value from iterator
+ and returns either false indicating that the iterator has reached its end or the IteratorResult
+ object if a next value is available. IteratorStep performs the following steps:
The abstract operation IteratorClose with arguments iterator and completion is used to notify an
+ iterator that it should perform any actions it would normally perform when it has reached its completed state:
The abstract operation CreateIterResultObject with arguments value and done creates an object that
+ supports the IteratorResult interface by performing the following steps:
The abstract operation CreateListIterator with argument list creates an Iterator (25.1.1.2) object whose next method returns the successive elements of list.
+ It performs the following steps:
+
+
+
Let iterator be ObjectCreate(%IteratorPrototype%, «[[IteratorNext]],
+ [[IteratedList]], [[ListIteratorNextIndex]]»).
A Lexical Environment is a specification type used to define the association of Identifiers to specific variables and functions based upon the lexical nesting structure of ECMAScript
+ code. A Lexical Environment consists of an Environment Record and a possibly null
+ reference to an outer Lexical Environment. Usually a Lexical Environment is associated with some specific syntactic
+ structure of ECMAScript code such as a FunctionDeclaration, a BlockStatement, or a Catch clause of a TryStatement and a
+ new Lexical Environment is created each time such code is evaluated.
+
+
An Environment Record records the identifier bindings that are created within the
+ scope of its associated Lexical Environment. It is referred to as the Lexical Environment’s EnvironmentRecord
+
+
The outer environment reference is used to model the logical nesting of Lexical Environment values. The outer reference
+ of a (inner) Lexical Environment is a reference to the Lexical Environment that logically surrounds the inner Lexical
+ Environment. An outer Lexical Environment may, of course, have its own outer Lexical Environment. A Lexical Environment may
+ serve as the outer environment for multiple inner Lexical Environments. For example, if a FunctionDeclaration contains two nested FunctionDeclarations then the Lexical
+ Environments of each of the nested functions will have as their outer Lexical Environment the Lexical Environment of the
+ current evaluation of the surrounding function.
+
+
A global environment is a Lexical Environment which does not have an outer environment. The global
+ environment’s outer environment reference is null. A global environment’s Environment Record may be prepopulated with identifier bindings and includes an
+ associated global object whose properties provide some of the global
+ environment’s identifier bindings. This global object is the value of a global environment’s
+ this binding. As ECMAScript code is executed, additional properties may be added to the global object and the
+ initial properties may be modified.
+
+
A module environment is a Lexical Environment that contains the bindings for the top level declarations of a Module. It also contains the bindings that are explicitly imported by the Module.
+ The outer environment of a module environment is a global environment.
+
+
A function environment is a Lexical Environment that corresponds to the invocation of an ECMAScript function object. A function environment may establish a new
+ this binding. A function environment also captures the state necessary to support super method
+ invocations.
+
+
Lexical Environments and Environment Record values are purely specification
+ mechanisms and need not correspond to any specific artefact of an ECMAScript implementation. It is impossible for an
+ ECMAScript program to directly access or manipulate such values.
There are two primary kinds of Environment Record values used in this specification: declarative Environment
+ Records and object Environment Records. Declarative Environment Records are used to define the effect of
+ ECMAScript language syntactic elements such as FunctionDeclarations, VariableDeclarations, and Catch clauses that directly associate identifier
+ bindings with ECMAScript language values. Object Environment Records are used
+ to define the effect of ECMAScript elements such as WithStatement that associate identifier
+ bindings with the properties of some object. Global Environment Records and
+ function Environment Records are specializations that are used for specifically for Script global
+ declarations and for top-level declarations within functions.
+
+
For specification purposes Environment Record values are values of the Record specification type and can be thought of
+ as existing in a simple object-oriented hierarchy where Environment Record is an abstract class with three concrete
+ subclasses, declarative Environment Record, object Environment Record, and global Environment Record. Function Environment Records and module Environment Records are subclasses of
+ declarative Environment Record. The abstract class includes the abstract specification methods defined in Table 15. These abstract methods have distinct concrete algorithms for each of the concrete
+ subclasses.
+
+
+ Table 15 — Abstract Methods of Environment Records
+
+
+
Method
+
Purpose
+
+
+
HasBinding(N)
+
Determine if an Environment Record has a binding for the String value N. Return true if it does and false if it does not
+
+
+
CreateMutableBinding(N, D)
+
Create a new but uninitialized mutable binding in an Environment Record. The String value N is the text of the bound name. If the optional Boolean argument D is true the binding is may be subsequently deleted.
+
+
+
CreateImmutableBinding(N, S)
+
Create a new but uninitialized immutable binding in an Environment Record. The String value N is the text of the bound name. If S is true then attempts to access the value of the binding before it is initialized or set it after it has been initialized will always throw an exception, regardless of the strict mode setting of operations that reference that binding. S is an optional parameter that defaults to false.
+
+
+
InitializeBinding(N,V)
+
Set the value of an already existing but uninitialized binding in an Environment Record. The String value N is the text of the bound name. V is the value for the binding and is a value of any ECMAScript language type.
+
+
+
SetMutableBinding(N,V, S)
+
Set the value of an already existing mutable binding in an Environment Record. The String value N is the text of the bound name. V is the value for the binding and may be a value of any ECMAScript language type. S is a Boolean flag. If S is true and the binding cannot be set throw a TypeError exception.
+
+
+
GetBindingValue(N,S)
+
Returns the value of an already existing binding from an Environment Record. The String value N is the text of the bound name. S is used to identify references originating in strict mode code or that otherwise require strict mode reference semantics. If S is true and the binding does not exist throw a ReferenceError exception. If the binding exists but is uninitialized a ReferenceError is thrown, regardless of the value of S.
+
+
+
DeleteBinding(N)
+
Delete a binding from an Environment Record. The String value N is the text of the bound name. If a binding for N exists, remove the binding and return true. If the binding exists but cannot be removed return false. If the binding does not exist return true.
+
+
+
HasThisBinding()
+
Determine if an Environment Record establishes a this binding. Return true if it does and false if it does not.
+
+
+
HasSuperBinding()
+
Determine if an Environment Record establishes a super method binding. Return true if it does and false if it does not.
+
+
+
WithBaseObject ()
+
If this Environment Record is associated with a with statement, return the with object. Otherwise, return undefined.
Each declarative Environment Record is associated with an ECMAScript program
+ scope containing variable, constant, let, class, module, import, and/or function declarations. A declarative Environment Record binds the set of identifiers defined by the declarations
+ contained within its scope.
+
+
The behaviour of the concrete specification methods for declarative environment records is defined by the following
+ algorithms.
The concrete Environment Record method HasBinding for declarative Environment
+ Records simply determines if the argument identifier is one of the identifiers bound by the record:
+
+
+
Let envRec be the declarative Environment Record for which the
+ method was invoked.
+
If envRec has a binding for the name that is the value of N, return true.
The concrete Environment Record method CreateMutableBinding for declarative
+ Environment Records creates a new mutable binding for the name N that is uninitialized. A binding must not
+ already exist in this Environment Record for N. If Boolean argument
+ D is provided and has the value true the new binding is marked as being subject to deletion.
+
+
+
Let envRec be the declarative Environment Record for which the
+ method was invoked.
+
Assert: envRec does not already have a binding for N.
+
Create a mutable binding in envRec for N and record that it is uninitialized. If D is
+ true record that the newly created binding may be deleted by a subsequent DeleteBinding call.
The concrete Environment Record method CreateImmutableBinding for declarative
+ Environment Records creates a new immutable binding for the name N that is uninitialized. A binding must not
+ already exist in this Environment Record for N. If Boolean argument
+ S is provided and has the value true the new binding is marked as a strict binding.
+
+
+
Let envRec be the declarative Environment Record for which the
+ method was invoked.
+
Assert: envRec does not already have a binding for N.
+
Create an immutable binding in envRec for N and record that it is uninitialized. If S is
+ true record that the newly created binding is a strict binding.
The concrete Environment Record method InitializeBinding for declarative
+ Environment Records is used to set the bound value of the current binding of the identifier whose name is the value of
+ the argument N to the value of argument V. An uninitialized binding for N must already
+ exist.
+
+
+
Let envRec be the declarative Environment Record for which the
+ method was invoked.
+
Assert: envRec must have an uninitialized binding for
+ N.
+
Set the bound value for N in envRec to V.
+
Record that the binding for N in envRec has been initialized.
The concrete Environment Record method SetMutableBinding for declarative
+ Environment Records attempts to change the bound value of the current binding of the identifier whose name is the value
+ of the argument N to the value of argument V. A binding for N normally already exist,
+ but in rare cases it may not. If the binding is an immutable binding, a TypeError is thrown if S is true.
+
+
+
Let envRec be the declarative Environment Record for which the
+ method was invoked.
The concrete Environment Record method GetBindingValue for declarative
+ Environment Records simply returns the value of its bound identifier whose name is the value of the argument
+ N. If the binding exists but is uninitialized a ReferenceError is thrown, regardless of the value of
+ S.
+
+
+
Let envRec be the declarative Environment Record for which the
+ method was invoked.
The concrete Environment Record method DeleteBinding for declarative
+ Environment Records can only delete bindings that have been explicitly designated as being subject to deletion.
+
+
+
Let envRec be the declarative Environment Record for which the
+ method was invoked.
+
Assert: envRec has a binding for the name that is the value of
+ N.
+
If the binding for N in envRec cannot be deleted, return false.
Each object Environment Record is associated with an object called its
+ binding object. An object Environment Record binds the set of string
+ identifier names that directly correspond to the property names of its binding object. Property keys that are not
+ strings in the form of an IdentifierName are not included in the set of bound identifiers. Both
+ own and inherited properties are included in the set regardless of the setting of their [[Enumerable]] attribute.
+ Because properties can be dynamically added and deleted from objects, the set of identifiers bound by an object Environment Record may potentially change as a side-effect of any operation that
+ adds or deletes properties. Any bindings that are created as a result of such a side-effect are considered to be a
+ mutable binding even if the Writable attribute of the corresponding property has the value false. Immutable
+ bindings do not exist for object Environment Records.
+
+
Object Environment Records created for with statements (13.10) can
+ provide their binding object as an implicit this value for use in function calls. The capability is controlled by
+ a withEnvironment Boolean value that is associated with each object Environment Record. By default, the value of withEnvironment is
+ false for any object Environment Record.
+
+
The behaviour of the concrete specification methods for object environment records is defined by the following
+ algorithms.
The concrete Environment Record method HasBinding for object Environment
+ Records determines if its associated binding object has a property whose name is the value of the argument
+ N:
+
+
+
Let envRec be the object Environment Record for which the method was
+ invoked.
The concrete Environment Record method CreateMutableBinding for object
+ Environment Records creates in an Environment Record’s associated binding object a property whose name is the
+ String value and initializes it to the value undefined. If Boolean argument D is provided and has the
+ value true the new property’s [[Configurable]] attribute is set to true, otherwise it is set to
+ false.
+
+
+
Let envRec be the object Environment Record for which the method was
+ invoked.
+
Let bindings be the binding object for envRec.
+
If D is true then let configValue be true otherwise let configValue be
+ false.
NOTE Normally envRec will not have a binding for N but if it does, the
+ semantics of DefinePropertyOrThrow may result in an existing binding being
+ replaced or shadowed or cause an abrupt completion to be
+ returned.
The concrete Environment Record method CreateImmutableBinding is never used
+ within this specification in association with Object Environment Records.
The concrete Environment Record method InitializeBinding for object
+ Environment Records is used to set the bound value of the current binding of the identifier whose name is the value of
+ the argument N to the value of argument V. An uninitialized binding for N must already
+ exist.
+
+
+
Let envRec be the object Environment Record for which the method was
+ invoked.
+
Assert: envRec must have an uninitialized binding for
+ N.
+
Record that the binding for N in envRec has been initialized.
+
Return envRec.SetMutableBinding(N, V, false).
+
+
+
+
NOTE In this specification, all uses of CreateMutableBinding for object Environment Records
+ are immediately followed by a call to InitializeBinding for the same name. Hence, implementations do not need to
+ explicitly track the initialization state of individual object Environment Record bindings.
The concrete Environment Record method SetMutableBinding for object
+ Environment Records attempts to set the value of the Environment Record’s associated binding object’s
+ property whose name is the value of the argument N to the value of argument V. A property named
+ N normally already exists but if it does not or is not currently writable, error handling is determined by
+ the value of the Boolean argument S.
+
+
+
Let envRec be the object Environment Record for which the method was
+ invoked.
The concrete Environment Record method GetBindingValue for object Environment
+ Records returns the value of its associated binding object’s property whose name is the String value of the
+ argument identifier N. The property should already exist but if it does not the result depends upon the value
+ of the S argument:
+
+
+
Let envRec be the object Environment Record for which the method was
+ invoked.
The concrete Environment Record method DeleteBinding for object Environment
+ Records can only delete bindings that correspond to properties of the environment object whose [[Configurable]]
+ attribute have the value true.
+
+
+
Let envRec be the object Environment Record for which the method was
+ invoked.
A function Environment Record is a declarative Environment Record that is used to represent the top-level scope of a function and,
+ if the function is not an ArrowFunction, provides a this binding. If a function is
+ not an ArrowFunction function and references super, its function Environment Record also contains the state that is used to perform
+ super method invocations from within the function.
+
+
Function Environment Records have the additional state fields listed in Table 16.
+
+
+ Table 16 — Additional Fields of Function Environment Records
+
+
+
Field Name
+
Value
+
Meaning
+
+
+
[[thisValue]]
+
Any
+
This is the this value used for this invocation of the function.
+
+
+
[[thisBindingStatus]]
+
"lexical" | "initialized" | "uninitialized"
+
If the value is "lexical", this is an ArrowFunction and does not have a local this value.
+
+
+
[[FunctionObject]]
+
Object
+
The function Object whose invocation caused this Environment Record to be created.
+
+
+
[[HomeObject]]
+
Object | undefined
+
If the associated function has super property accesses and is not an ArrowFunction, [[HomeObject]] is the object that the function is bound to as a method. The default value for [[HomeObject]] is undefined.
+
+
+
[[NewTarget]]
+
Object | undefined
+
If this Environment Record was created by the [[Construct]] internal method, [[NewTarget]] is the value of the [[Construct]] newTarget parameter. Otherwise, its value is undefined.
+
+
+
+
+
Function Environment Records support all of the declarative Environment Record methods listed in Table 15 and share the same specifications for all of those methods except for HasThisBinding and
+ HasSuperBinding. In addition, function Environment Records support the methods listed in Table
+ 17:
+
+
+ Table 17 — Additional Methods of Function Environment Records
+
Return the object that is the base for super property accesses bound in this Environment Record. The object is derived from this Environment Record’s [[HomeObject]] field. The value undefined indicates that super property accesses will produce runtime errors.
+
+
+
+
+
The behaviour of the additional concrete specification methods for function Environment Records is defined by the
+ following algorithms:
A global Environment Record is used to represent the outer most scope that is
+ shared by all of the ECMAScript Script elements that are processed in a common Realm (8.2). A global Environment Record provides the bindings for built-in globals (clause 18), properties of the global object, and for all top-level declarations (13.1.8, 13.1.10) that occur within a Script.
+
+
A global Environment Record is logically a single record but it is specified
+ as a composite encapsulating an object Environment Record and a declarative Environment Record. The object Environment
+ Record has as its base object the global object of the associated Realm. This global
+ object is the value returned by the global Environment Record’s
+ GetThisBinding concrete method. The object Environment Record component of a
+ global Environment Record contains the bindings for all built-in globals (clause 18) and all bindings introduced by a FunctionDeclaration, GeneratorDeclaration, or VariableStatement
+ contained in global code. The bindings for all other ECMAScript declarations in global code are contained in the
+ declarative Environment Record component of the global Environment Record.
+
+
Properties may be created directly on a global object. Hence, the object Environment Record component of a global Environment Record may contain both bindings created explicitly by FunctionDeclaration, GeneratorDeclaration, or VariableDeclaration declarations and binding created implicitly as properties of the global object. In
+ order to identify which bindings were explicitly created using declarations, a global Environment Record maintains a list of the names bound using its
+ CreateGlobalVarBindings and CreateGlobalFunctionBindings concrete methods.
+
+
Global Environment Records have the additional fields listed in Table 18 and the additional
+ methods listed in Table 19.
+
+
+ Table 18 — Additional Fields of Global Environment Records
+
Binding object is the global object. It contains global built-in bindings as well as FunctionDeclaration, GeneratorDeclaration, and VariableDeclaration bindings in global code for the associated Realm.
Contains bindings for all declarations in global code for the associated Realm code except for FunctionDeclaration, GeneratorDeclaration, and VariableDeclarationbindings.
Determines if the argument identifier has a binding in this Environment Record that was created using a VariableDeclaration,FunctionDeclaration, or GeneratorDeclaration.
Determines if the argument identifier has a binding in this Environment Record that was created using a lexical declaration such as a LexicalDeclaration or a ClassDeclaration.
Used to create and initialize to undefined a global var binding in the [[ObjectRecord]] component of a global Environment Record. The binding will be a mutable binding. The corresponding global object property will have attribute values appropriate for a var. The String value N is the bound name. If D is true the binding may be deleted. Logically equivalent to CreateMutableBinding followed by a SetMutableBinding but it allows var declarations to receive special treatment.
Create and initialize a global function binding in the [[ObjectRecord]] component of a global Environment Record. The binding will be a mutable binding. The corresponding global object property will have attribute values appropriate for a function. The String value N is the bound name. V is the initialization value. If the optional Boolean argument D is true the binding is may be deleted. Logically equivalent to CreateMutableBinding followed by a SetMutableBinding but it allows function declarations to receive special treatment.
+
+
+
+
+
The behaviour of the concrete specification methods for global Environment Records is defined by the following
+ algorithms.
The concrete Environment Record method HasBinding for global Environment
+ Records simply determines if the argument identifier is one of the identifiers bound by the record:
+
+
+
Let envRec be the global Environment Record for which the method was
+ invoked.
The concrete Environment Record method CreateMutableBinding for global
+ Environment Records creates a new mutable binding for the name N that is uninitialized. The binding is
+ created in the associated DeclarativeRecord. A binding for N must not already exist in the DeclarativeRecord.
+ If Boolean argument D is provided and has the value true the new binding is marked as being subject to
+ deletion.
+
+
+
Let envRec be the global Environment Record for which the method was
+ invoked.
+
Let DclRec be envRec.[[DeclarativeRecord]].
+
If DclRec.HasBinding(N) is true, throw a TypeError exception.
The concrete Environment Record method CreateImmutableBinding for global
+ Environment Records creates a new immutable binding for the name N that is uninitialized. A binding must not
+ already exist in this Environment Record for N. If Boolean argument
+ S is provided and has the value true the new binding is marked as a strict binding.
+
+
+
Let envRec be the global Environment Record for which the method was
+ invoked.
+
Let DclRec be envRec.[[DeclarativeRecord]].
+
If DclRec.HasBinding(N) is true, throw a TypeError exception.
The concrete Environment Record method InitializeBinding for global
+ Environment Records is used to set the bound value of the current binding of the identifier whose name is the value of
+ the argument N to the value of argument V. An uninitialized binding for N must already
+ exist.
+
+
+
Let envRec be the global Environment Record for which the method was
+ invoked.
The concrete Environment Record method SetMutableBinding for global
+ Environment Records attempts to change the bound value of the current binding of the identifier whose name is the value
+ of the argument N to the value of argument V. If the binding is an immutable binding, a
+ TypeError is thrown if S is true. A
+ property named N normally already exists but if it does not or is not currently writable, error handling is
+ determined by the value of the Boolean argument S.
+
+
+
Let envRec be the global Environment Record for which the method was
+ invoked.
The concrete Environment Record method GetBindingValue for global Environment
+ Records returns the value of its bound identifier whose name is the value of the argument N. If the binding
+ is an uninitialized binding throw a ReferenceError exception. A property named N normally already
+ exists but if it does not or is not currently writable, error handling is determined by the value of the Boolean
+ argument S.
+
+
+
Let envRec be the global Environment Record for which the method was
+ invoked.
The concrete Environment Record method DeleteBinding for global Environment
+ Records can only delete bindings that have been explicitly designated as being subject to deletion.
+
+
+
Let envRec be the global Environment Record for which the method was
+ invoked.
+
Let DclRec be envRec.[[DeclarativeRecord]].
+
If DclRec.HasBinding(N) is true, then
+
+
Return DclRec.DeleteBinding(N).
+
+
+
Let ObjRec be envRec.[[ObjectRecord]].
+
Let globalObject be the binding object for ObjRec.
The concrete Environment Record method HasVarDeclaration for global
+ Environment Records determines if the argument identifier has a binding in this record that was created using a VariableStatement or a FunctionDeclaration:
+
+
+
Let envRec be the global Environment Record for which the method was
+ invoked.
+
Let varDeclaredNames be envRec.[[VarNames]].
+
If varDeclaredNames contains the value of N, return true.
The concrete Environment Record method HasLexicalDeclaration for global
+ Environment Records determines if the argument identifier has a binding in this record that was created using a lexical
+ declaration such as a LexicalDeclaration or a ClassDeclaration:
+
+
+
Let envRec be the global Environment Record for which the method was
+ invoked.
The concrete Environment Record method HasRestrictedGlobalProperty for global
+ Environment Records determines if the argument identifier is the name of a property of the global object that must not
+ be shadowed by a global lexically binding:
+
+
+
Let envRec be the global Environment Record for which the method was
+ invoked.
+
Let ObjRec be envRec.[[ObjectRecord]].
+
Let globalObject be the binding object for ObjRec.
+
Let existingProp be globalObject.[[GetOwnProperty]](N).
If existingProp.[[Configurable]] is true, return false.
+
Return true.
+
+
+
+
NOTE Properties may exist upon a global object that were directly created rather than being
+ declared using a var or function declaration. A global lexical binding may not be created that has the same name as a
+ non-configurable property of the global object. The global property undefined is an example of such a
+ property.
The concrete Environment Record method CanDeclareGlobalVar for global
+ Environment Records determines if a corresponding CreateGlobalVarBinding call
+ would succeed if called for the same argument N. Redundant var declarations and var declarations for
+ pre-existing global object properties are allowed.
+
+
+
Let envRec be the global Environment Record for which the method was
+ invoked.
+
Let ObjRec be envRec.[[ObjectRecord]].
+
Let globalObject be the binding object for ObjRec.
The concrete Environment Record method CanDeclareGlobalFunction for global
+ Environment Records determines if a corresponding CreateGlobalFunctionBinding call would succeed if called for the same
+ argument N.
+
+
+
Let envRec be the global Environment Record for which the method was
+ invoked.
+
Let ObjRec be envRec.[[ObjectRecord]].
+
Let globalObject be the binding object for ObjRec.
+
Let existingProp be globalObject.[[GetOwnProperty]](N).
The concrete Environment Record method CreateGlobalVarBinding for global
+ Environment Records creates and initializes a mutable binding in the associated object Environment Record and records
+ the bound name in the associated [[VarNames]] List. If a binding
+ already exists, it is reused and assumed to be initialized.
+
+
+
Let envRec be the global Environment Record for which the method was
+ invoked.
+
Let ObjRec be envRec.[[ObjectRecord]].
+
Let globalObject be the binding object for ObjRec.
The concrete Environment Record method CreateGlobalFunctionBinding for global
+ Environment Records creates and initializes a mutable binding in the associated object Environment Record and records
+ the bound name in the associated [[VarNames]] List. If a binding
+ already exists, it is replaced.
+
+
+
Let envRec be the global Environment Record for which the method was
+ invoked.
+
Let ObjRec be envRec.[[ObjectRecord]].
+
Let globalObject be the binding object for ObjRec.
+
Let existingProp be globalObject.[[GetOwnProperty]](N).
NOTE Global function declarations are always represented as own properties of the global
+ object. If possible, an existing own property is reconfigured to have a standard set of attribute values. Steps 10-12
+ are equivalent to what calling the InitializeBinding concrete method would do and if globalObject is a Proxy
+ will produce the same sequence of Proxy trap calls.
A module Environment Record is a declarative Environment Record that is used to represent the outer scope of an ECMAScript Module. In additional to normal mutable and immutable bindings, module Environment Records also
+ provide immutable import bindings which are bindings that provide indirect access to a target binding that exists in
+ another Environment Record.
+
+
Module Environment Records support all of the declarative Environment Record methods listed in Table 15 and share the same specifications for all of those methods except for GetBindingValue,
+ DeleteBinding, HasThisBinding and GetThisBinding. In addition, module Environment Records support the methods listed in
+ Table 20:
+
+
+ Table 20 — Additional Methods of Module Environment Records
+
Create an immutable indirect binding in a module Environment Record. The String value N is the text of the bound name. M is a Module Record (see 15.2.1.14), and N2 is a binding that exists in M’s module Environment Record.
The concrete Environment Record method GetBindingValue for module Environment
+ Records returns the value of its bound identifier whose name is the value of the argument N. However, if the
+ binding is an indirect binding the value of the target binding is returned. If the binding exists but is uninitialized a
+ ReferenceError is thrown, regardless of the value of S.
+
+
+
Let envRec be the module Environment Record for which the method was
+ invoked.
The concrete Environment Record method CreateImportBinding for module
+ Environment Records creates a new initialized immutable indirect binding for the name N. A binding must not
+ already exist in this Environment Record for N. M is a
+ Module Record (see 15.2.1.14), and N2 is the name of a binding
+ that exists in M’s module Environment Record. Accesses to the value of the
+ new binding will indirectly access the bound value of value of the target binding.
+
+
+
Let envRec be the module Environment Record for which the method was
+ invoked.
+
Assert: envRec does not already have a binding for N.
The abstract operation GetIdentifierReference is called with a Lexical
+ Environmentlex, a String name, and a Boolean flag strict. The value of
+ lex may be null. When called, the following steps are performed:
+
+
+
If lex is the value null, then
+
+
Return a value of type Reference whose base value is
+ undefined, whose referenced name is name, and whose strict reference flag is strict.
When the abstract operation NewObjectEnvironment is called with an Object O and a Lexical EnvironmentE as arguments, the following steps are performed:
Before it is evaluated, all ECMAScript code must be associated with a Realm. Conceptually, a realm consists of a
+ set of intrinsic objects, an ECMAScript global environment, all of the ECMAScript code that is loaded within the scope of
+ that global environment, and other associated state and resources.
+
+
A Realm is specified as a Record with the fields specified in Table 21:
+
+
+ Table 21 — Realm Record Fields
+
+
+
Field Name
+
Value
+
Meaning
+
+
+
[[intrinsics]]
+
Record whose field names are intrinsic keys and whose values are objects
+
These are the intrinsic values used by code associated with this Realm
A List of Record { [[strings]]: List, [[array]]: Object}.
+
Template objects are canonicalized separately for each Realm using its [[templateMap]]. Each [[strings]] value is a List containing, in source text order, the raw string values of a TemplateLiteral that has been evaluated. The associated [[array]] value is the corresponding template object that is passed to a tag function.
+
+
+
+
+
An implementation may define other, implementation specific fields.
Set fields of intrinsics with the values listed in Table 7 that have not already been
+ handled above. The field names are the names listed in column one of the table. The value of each field is a new
+ object value fully and recursively populated with property values as defined by the specification of each object in
+ clauses 18-26. All object property values are newly created object values. All values that are built-in function
+ objects are created by performing CreateBuiltinFunction(realmRec,
+ <steps>, <prototype>, <slots>) where <steps> is the definition of that function provided by
+ this specification, <prototype> is the specified value of the function’s [[Prototype]] internal slot and <slots> is a list of the names, if
+ any, of the functions specified internal slots. The creation of the intrinsics and their properties must be ordered to
+ avoid any dependencies upon objects that have not yet been created.
The abstract operation SetDefaultGlobalBindings with argument realmRec performs the following steps:
+
+
+
Let global be realmRec.[[globalThis]].
+
For each property of the Global Object specified in clause 18, do
+
+
Let name be the string value of the property name.
+
Let desc be the fully populated data property descriptor for the property containing the specified
+ attributes for the property. For properties listed in 18.2, 18.3, or 18.4 the value of the [[Value]] attribute is the
+ corresponding intrinsic object from realmRec.
An execution context is a specification device that is used to track the runtime evaluation of code by an
+ ECMAScript implementation. At any point in time, there is at most one execution context that is actually executing code.
+ This is known as the running execution context. A stack is used to track execution contexts. The running execution
+ context is always the top element of this stack. A new execution context is created whenever control is transferred from the
+ executable code associated with the currently running execution context to executable code that is not associated with that
+ execution context. The newly created execution context is pushed onto the stack and becomes the running execution
+ context.
+
+
An execution context contains whatever implementation specific state is necessary to track the execution progress of its
+ associated code. Each execution context has at least the state components listed in Table 22.
+
+
+ Table 22 —State Components for All Execution Contexts
+
+
+
Component
+
Purpose
+
+
+
code evaluation state
+
Any state needed to perform, suspend, and resume evaluation of the code associated with this execution context.
+
+
+
Function
+
If this execution context is evaluating the code of a function object, then the value of this component is that function object. If the context is evaluating the code of a Script or Module, the value is null.
The Realm from which associated code accesses ECMAScript resources.
+
+
+
+
+
Evaluation of code by the running execution context may be suspended at various points defined within this specification.
+ Once the running execution context has been suspended a different execution context may become the running execution context
+ and commence evaluating its code. At some later time a suspended execution context may again become the running execution
+ context and continue evaluating its code at the point where it had previously been suspended. Transition of the running
+ execution context status among execution contexts usually occurs in stack-like last-in/first-out manner. However, some
+ ECMAScript features require non-LIFO transitions of the running execution context.
+
+
The value of the Realm component of the running execution context is also called the
+ current Realm. The value of the Function component of the running execution context is
+ also called the active function object.
+
+
Execution contexts for ECMAScript code have the additional state components listed in Table
+ 23.
+
+
+ Table 23 — Additional State Components for ECMAScript Code Execution Contexts
+
+
+
Component
+
Purpose
+
+
+
LexicalEnvironment
+
Identifies the Lexical Environment used to resolve identifier references made by code within this execution context.
+
+
+
VariableEnvironment
+
Identifies the Lexical Environment whose EnvironmentRecord holds bindings created by VariableStatements within this execution context.
+
+
+
+
+
The LexicalEnvironment and VariableEnvironment components of an execution context are always Lexical Environments. When
+ an execution context is created its LexicalEnvironment and VariableEnvironment components initially have the same value.
+
+
Execution contexts representing the evaluation of generator objects have the additional state components listed in Table 24.
+
+
+ Table 24 — Additional State Components for Generator Execution Contexts
+
+
+
Component
+
Purpose
+
+
+
Generator
+
The GeneratorObject that this execution context is evaluating.
+
+
+
+
+
In most situations only the running execution context (the top of the execution context stack) is directly manipulated by
+ algorithms within this specification. Hence when the terms “LexicalEnvironment”, and
+ “VariableEnvironment” are used without qualification they are in reference to those components of the running
+ execution context.
+
+
An execution context is purely a specification mechanism and need not correspond to any particular artefact of an
+ ECMAScript implementation. It is impossible for ECMAScript code to directly access or observe an execution context.
The ResolveBinding abstract operation is used to determine the binding of name passed as a string value. The
+ optional argument env can be used to explicitly provide the Lexical
+ Environment that is to be searched for the binding. During execution of ECMAScript code, ResolveBinding is performed
+ using the following algorithm:
+
+
+
If env was not passed or if env is undefined, then
+
+
If the code matching the syntactic production that is being evaluated is contained in strict mode code, let strict be true, else let strict be
+ false.
The abstract operation GetThisEnvironment finds the Environment Record that currently supplies the binding of the keyword this.
+ GetThisEnvironment performs the following steps:
The abstract operation ResolveThisBinding determines the binding of the keyword this using the LexicalEnvironment of the running execution
+ context. ResolveThisBinding performs the following steps:
The abstract operation GetGlobalObject returns the global object used
+ by the currently running execution context. GetGlobalObject performs the following steps:
A Job is an abstract operation that initiates an ECMAScript computation when no other ECMAScript computation is currently
+ in progress. A Job abstract operation may be defined to accept an arbitrary set of job parameters.
+
+
Execution of a Job can be initiated only when there is no running execution context
+ and the execution context stack is empty. A PendingJob is a request for the future
+ execution of a Job. A PendingJob is an internal Record whose fields are specified in Table 25. Once
+ execution of a Job is initiated, the Job always executes to completion. No other Job may be initiated until the currently
+ running Job completes. However, the currently running Job or external events may cause the enqueuing of additional
+ PendingJobs that may be initiated sometime after completion of the currently running Job.
+
+
+ Table 25 — PendingJob Record Fields
+
+
+
Field Name
+
Value
+
Meaning
+
+
+
[[Job]]
+
The name of a Job abstract operation
+
This is the abstract operation that is performed when execution of this PendingJob is initiated. Jobs are abstract operations that use NextJob rather than Return to indicate that they have completed.
Field reserved for use by host environments that need to associate additional information with a pending Job.
+
+
+
+
+
A Job Queue is a FIFO queue of PendingJob records. Each Job Queue has a name and the full set of available Job Queues are
+ defined by an ECMAScript implementation. Every ECMAScript implementation has at least the Job Queues defined in Table 26.
+
+
+ Table 26 — Required Job Queues
+
+
+
Name
+
Purpose
+
+
+
ScriptJobs
+
Jobs that validate and evaluate ECMAScript Script and Module source text. See clauses 10 and 15.
+
+
+
PromiseJobs
+
Jobs that are responses to the settlement of a Promise (see 25.4).
+
+
+
+
+
A request for the future execution of a Job is made by enqueueing, on a Job Queue, a PendingJob record that includes a
+ Job abstract operation name and any necessary argument values. When there is no running execution context and the execution context stack
+ is empty, the ECMAScript implementation removes the first PendingJob from a Job Queue and uses the information contained in
+ it to create an execution context and starts execution of the associated Job abstract
+ operation.
+
+
The PendingJob records from a single Job Queue are always initiated in FIFO order. This specification does not define the
+ order in which multiple Job Queues are serviced. An ECMAScript implementation may interweave the FIFO evaluation of the
+ PendingJob records of a Job Queue with the evaluation of the PendingJob records of one or more other Job Queues. An
+ implementation must define what occurs when there are no running execution context and
+ all Job Queues are empty.
+
+
+
NOTE Typically an ECMAScript implementation will have its Job Queues pre-initialized with at
+ least one PendingJob and one of those Jobs will be the first to be executed. An implementation might choose to free all
+ resources and terminate if the current Job completes and all Job Queues are empty. Alternatively, it might choose to wait
+ for a some implementation specific agent or mechanism to enqueue new PendingJob requests.
+
+
+
The following abstract operations are used to create and manage Jobs and Job Queues:
Let pending be PendingJob{ [[Job]]: job, [[Arguments]]: arguments, [[Realm]]: callerRealm,
+ [[HostDefined]]: undefined }.
+
Perform any implementation or host environment defined processing of pending. This may include modifying the
+ [[HostDefined]] field or any other field of pending.
+
Add pending at the back of the Job Queue named by queueName.
Let nextQueue be a non-empty Job Queue chosen in an implementation defined manner. If all Job Queues are empty,
+ the result is implementation defined.
+
Let nextPending be the PendingJob record at the front of nextQueue. Remove that record from
+ nextQueue.
In an implementation dependent manner, obtain the ECMAScript source texts (see clause 10) for zero or more ECMAScript scripts and/or ECMAScript
+ modules. For each such sourceText do,
+
+
If sourceText is the source code of a script, then
+
+
The abstract operation InitializeHostDefinedRealm with parameter realm performs the following steps:
+
+
+
If this implementation requires use of an exotic object to serve as realm’s global object, let
+ global be such an object created in an implementation defined manner. Otherwise, let global be
+ undefined indicating that an ordinary object should be created as the global object.
9.1 Ordinary Object Internal Methods and Internal Slots
+
+
All ordinary objects have an internal slot called
+ [[Prototype]]. The value of this internal slot is either
+ null or an object and is used for implementing inheritance. Data properties of the [[Prototype]] object are inherited
+ (are visible as properties of the child object) for the purposes of get access, but not for set access. Accessor properties
+ are inherited for both get access and set access.
+
+
Every ordinary object has a Boolean-valued [[Extensible]] internal slot that controls whether or not properties may be
+ added to the object. If the value of the [[Extensible]] internal
+ slot is false then additional properties may not be added to the object. In addition, if [[Extensible]] is
+ false the value of the [[Prototype]] internal slot of
+ the object may not be modified. Once the value of an object’s [[Extensible]] internal slot has been set to false it may not be
+ subsequently changed to true.
If the [[GetPrototypeOf]] internal method of p is not the ordinary object internal method defined in 9.1.1, let done be
+ true.
+
Else, let p be the value of p’s [[Prototype]] internal slot.
+
+
+
+
+
Set the value of the [[Prototype]] internal slot of
+ O to V.
+
Return true.
+
+
+
+
NOTE The loop in step 8 guarantees that there will be no circularities in any prototype chain
+ that only includes objects that use the ordinary object definitions for [[GetPrototypeOf]] and [[SetPrototypeOf]].
When the abstract operation OrdinaryDefineOwnProperty is called with
+ Object O, property keyP, and Property DescriptorDesc the following steps are taken:
When the abstract operation IsCompatiblePropertyDescriptor is called
+ with Boolean value Extensible, and Property Descriptors Desc, and Current the following steps are taken:
When the abstract operation ValidateAndApplyPropertyDescriptor is
+ called with Object O, property keyP, Boolean value extensible, and Property Descriptors Desc, and
+ current the following steps are taken:
+
+
This algorithm contains steps that test various fields of the Property DescriptorDesc for specific
+ values. The fields that are tested in this manner need not actually exist in Desc. If a field is
+ absent then its value is considered to be false.
+
+
+
NOTE If undefined is passed as the O argument only validation is performed and
+ no object updates are performed.
If O is not undefined, create an own data property named P of object O whose
+ [[Value]], [[Writable]], [[Enumerable]] and [[Configurable]] attribute values are described by Desc.
+ If the value of an attribute field of Desc is absent, the attribute of the newly created property is
+ set to its default value.
If O is not undefined, create an own accessor property named P of object O whose
+ [[Get]], [[Set]], [[Enumerable]] and [[Configurable]] attribute values are described by Desc. If the
+ value of an attribute field of Desc is absent, the attribute of the newly created property is set to
+ its default value.
+
+
+
Return true.
+
+
+
Return true, if every field in Desc is absent.
+
Return true, if every field in Desc also occurs in current and the value of every field in
+ Desc is the same value as the corresponding field in current when compared using the SameValue algorithm.
+
If the [[Configurable]] field of current is false, then
+
+
Return false, if the [[Configurable]] field of Desc is true.
+
Return false, if the [[Enumerable]] field of Desc is present and the [[Enumerable]] fields of
+ current and Desc are the Boolean negation of each other.
If O is not undefined, convert the property named P of object O from a data
+ property to an accessor property. Preserve the existing values of the converted property’s
+ [[Configurable]] and [[Enumerable]] attributes and set the rest of the property’s attributes to their
+ default values.
+
+
+
Else,
+
+
If O is not undefined, convert the property named P of object O from an accessor
+ property to a data property. Preserve the existing values of the converted property’s [[Configurable]]
+ and [[Enumerable]] attributes and set the rest of the property’s attributes to their default
+ values.
If the [[Configurable]] field of current is false, then
+
+
Return false, if the [[Set]] field of Desc is present and SameValue(Desc.[[Set]], current.[[Set]]) is false.
+
Return false, if the [[Get]] field of Desc is present and SameValue(Desc.[[Get]], current.[[Get]]) is false.
+
+
+
+
+
If O is not undefined, then
+
+
For each field of Desc that is present, set the corresponding attribute of the property named P of
+ object O to the value of the field.
+
+
+
Return true.
+
+
+
+
NOTE Step 8.b allows any field of Desc to be different from the corresponding field of
+ current if current’s [[Configurable]] field is true. This even permits changing the [[Value]] of a property
+ whose [[Writable]] attribute is false. This is allowed because a true [[Configurable]] attribute would
+ permit an equivalent sequence of calls where [[Writable]] is first set to true, a new [[Value]] is set, and then
+ [[Writable]] is set to false.
When the [[Enumerate]] internal method of O is called the following steps are taken:
+
+
+
Return an Iterator object (25.1.1.2) whose next method iterates
+ over all the String-valued keys of enumerable properties of O. The Iterator object must inherit from
+ %IteratorPrototype% (25.1.2). The mechanics and order of enumerating the
+ properties is not specified but must conform to the rules specified below.
+
+
+
The iterator’s next method processes object properties to determine whether the property key should be returned as an iterator value. Returned property keys do not include keys
+ that are Symbols. Properties of the target object may be deleted during enumeration. A property that is deleted before it is
+ processed by the iterator’s next method is ignored. If new properties are added to the target object
+ during enumeration, the newly added properties are not guaranteed to be processed in the active enumeration. A property name
+ will be returned by the iterator’s next method at most once in any enumeration.
+
+
Enumerating the properties of the target object includes enumerating properties of its prototype, and the prototype of
+ the prototype, and so on, recursively; but a property of a prototype is not processed if it has the same name as a property
+ that has already been processed by the iterator’s next method. The values of [[Enumerable]] attributes
+ are not considered when determining if a property of a prototype object has already been processed. The enumerable property
+ names of prototype objects must be obtained as if by invoking the prototype object’s [[Enumerate]] internal method.
+ [[Enumerate]] must obtain the own property keys of the target object as if by calling its [[OwnPropertyKeys]] internal
+ method. Property attributes of the target object must be obtained as if by calling its [[GetOwnProperty]] internal
+ method.
+
+
NOTE The following is an informative definition of an ECMAScript generator function that conforms to these
+ rules:
The abstract operation ObjectCreate with argument proto (an object or null) is used to specify the runtime
+ creation of new ordinary objects. The optional argument internalSlotsList is a List of the names of additional internal slots that must be defined as
+ part of the object. If the list is not provided, an empty List is
+ used. This abstract operation performs the following steps:
+
+
+
If internalSlotsList was not provided, let internalSlotsList be an empty List.
+
Let obj be a newly created object with an internal
+ slot for each name in internalSlotsList.
+
Set obj’s essential internal methods to the default ordinary object definitions specified in 9.1.
+
Set the [[Prototype]] internal slot of obj to
+ proto.
+
Set the [[Extensible]] internal slot of obj to
+ true.
The abstract operation OrdinaryCreateFromConstructor creates an ordinary object whose [[Prototype]] value is retrieved
+ from a constructor’s prototype property, if it exists. Otherwise the intrinsic named by
+ intrinsicDefaultProto is used for [[Prototype]]. The optional internalSlotsList is a List of the names of additional internal slots that must be defined as
+ part of the object. If the list is not provided, an empty List is
+ used. This abstract operation performs the following steps:
+
+
+
Assert: intrinsicDefaultProto is a string value that is this
+ specification’s name of an intrinsic object. The corresponding object must be an intrinsic that is intended to
+ be used as the [[Prototype]] value of an object.
The abstract operation GetPrototypeFromConstructor determines the [[Prototype]] value that should be used to create an
+ object corresponding to a specific constructor. The value is retrieved from the constructor’s prototype
+ property, if it exists. Otherwise the intrinsic named by intrinsicDefaultProto is used for [[Prototype]]. This
+ abstract operation performs the following steps:
+
+
+
Assert: intrinsicDefaultProto is a string value that is this
+ specification’s name of an intrinsic object. The corresponding object must be an intrinsic that is intended to
+ be used as the [[Prototype]] value of an object.
Let proto be realm’s intrinsic object named intrinsicDefaultProto.
+
+
+
Return proto.
+
+
+
+
NOTE If constructor does not supply a [[Prototype]] value, the default value that is
+ used is obtained from the Code Realm of the constructor function rather than from the running execution context.
ECMAScript function objects encapsulate parameterized ECMAScript code closed over a lexical environment and support the dynamic evaluation of that code. An ECMAScript
+ function object is an ordinary object and has the same internal slots and the same internal methods as other ordinary
+ objects. The code of an ECMAScript function object may be either strict mode code (10.2.1) or non-strict mode code. An ECMAScript function
+ object whose code is strict mode code is called a strict function. One whose code
+ is not strict mode code is called a non-strict function.
+
+
ECMAScript function objects have the additional internal slots listed in Table 27.
+
+
+ Table 27 — Internal Slots of ECMAScript Function Objects
+
The Code Realm in which the function was created and which provides any intrinsic objects that are accessed when evaluating the function.
+
+
+
[[ThisMode]]
+
(lexical, strict, global)
+
Defines how this references are interpreted within the formal parameters and code body of the function. lexical means that this refers to the this value of a lexically enclosing function. strict means that the this value is used exactly as provided by an invocation of the function. global means that a this value of undefined is interpreted as a reference to the global object.
+
+
+
[[Strict]]
+
Boolean
+
true if this is a strict mode function, false if this is not a strict mode function.
+
+
+
[[HomeObject]]
+
Object
+
If the function uses super, this is the object whose [[GetPrototypeOf]] provides the object where super property lookups begin.
+
+
+
+
+
All ECMAScript function objects have the [[Call]] internal method defined here. ECMAScript functions that are also
+ constructors in addition have the [[Construct]] internal method. ECMAScript function objects whose code is not strict mode code have the [[GetOwnProperty]] internal method defined here.
NOTE When calleeContext is removed from the
+ execution context stack in step 8 it must not be destroyed if it is suspended
+ and retained for later resumption by an accessible generator object.
When the abstract operation PrepareForOrdinaryCall is called with function object Fand ECMAScript language value
+ newTarget, the following steps are taken:
When the abstract operation OrdinaryCallBindThis is called with function object F, execution contextcalleeContext, and ECMAScript value
+ thisArgument the following steps are taken:
+
+
+
Let thisMode be the value of F’s [[ThisMode]] internal slot.
The abstract operation FunctionAllocate requires the two arguments functionPrototype and strict. It also accepts one optional argument, functionKind.
+ FunctionAllocate performs the following steps:
Assert: If functionKind is present, its value is either
+ "normal", "non-constructor" or "generator".
+
If functionKind is not present, let functionKind be "normal".
+
If functionKind is "non-constructor", then
+
+
Let functionKind be "normal".
+
Let needsConstruct be false.
+
+
+
Else let needsConstruct be true.
+
Let F be a newly created ECMAScript function object with the
+ internal slots listed in Table 27. All of those internal slots are initialized to
+ undefined.
+
Set F’s essential internal methods to the default ordinary object definitions specified in 9.1.
+
Set F’s [[Call]] internal method to the definition specified in 9.2.1.
+
If needsConstruct is true, then
+
+
Set F’s [[Construct]] internal method to the definition specified in 9.2.2.
+
If functionKind is "generator", set the [[ConstructorKind]] internal slot of F to
+ "derived".
+
Else, set the [[ConstructorKind]] internal slot of
+ F to "base".
+
NOTE Generator functions are tagged as "derived" constructors to prevent [[Construct]] from
+ preallocating a generator instance. Generator instance objects are allocated when EvaluateBody is applied to the
+ GeneratorBody of a generator function.
The abstract operation FunctionInitialize requires the arguments: a function object F, kind which
+ is one of (Normal, Method, Arrow), a parameter list production specified by ParameterList, a body
+ production specified by Body, a Lexical Environment
+ specified by Scope. FunctionInitialize performs the following
+ steps:
+
+
+
Assert: F is an extensible object that does not have a
+ length own property.
+
Let len be the ExpectedArgumentCount of ParameterList.
+
Let status be DefinePropertyOrThrow(F, "length",
+ PropertyDescriptor{[[Value]]: len, [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]:
+ true}).
The abstract operation FunctionCreate requires the arguments: kind which is one of (Normal, Method, Arrow), a
+ parameter list production specified by ParameterList, a body production specified by Body, a Lexical Environment specified by Scope, a Boolean flag Strict, and optionally, an object prototype. FunctionCreate performs the following steps:
+
+
+
If the prototype argument was not passed, then
+
+
Let prototype be the intrinsic object %FunctionPrototype%.
+
+
+
If kind is not Normal, let allocKind be
+ "non-constructor".
The abstract operation GeneratorFunctionCreate requires the arguments: kind which is one of (Normal, Method),
+ a parameter list production specified by ParameterList, a body production specified by Body, a Lexical Environment specified by Scope, and a Boolean flag Strict. GeneratorFunctionCreate performs the following
+ steps:
+
+
+
Let functionPrototype be the intrinsic object %Generator%.
+
Let F be FunctionAllocate(functionPrototype, Strict,
+ "generator").
The abstract operation AddRestrictedFunctionProperties is called with a function object F and Realm Record realm as its argument. It performs the following steps:
+
+
+
Assert: realm.[[intrinsics]].[[%ThrowTypeError%]] exists and has been initialized.
+
Let thrower be realm.[[intrinsics]].[[%ThrowTypeError%]].
+
Let status be DefinePropertyOrThrow(F, "caller",
+ PropertyDescriptor {[[Get]]: thrower, [[Set]]: thrower, [[Enumerable]]: false,
+ [[Configurable]]: true}).
The %ThrowTypeError% intrinsic is an anonymous built-in function object that is defined once for each Realm. When %ThrowTypeError% is called it performs the following steps:
+
+
+
Throw a TypeError exception.
+
+
+
The value of the [[Extensible]] internal slot of a
+ %ThrowTypeError% function is false.
+
+
The length property of a %ThrowTypeError% function has the attributes { [[Writable]]: false,
+ [[Enumerable]]: false, [[Configurable]]: false }.
The abstract operation MakeConstructor requires a Function argument F and optionally, a Boolean
+ writablePrototype and an object prototype. If prototype is provided it is assumed to
+ already contain, if needed, a "constructor" property whose value is F. This operation converts
+ F into a constructor by performing the following steps:
Let status be DefinePropertyOrThrow(F,
+ "prototype", PropertyDescriptor{[[Value]]: prototype, [[Writable]]: writablePrototype,
+ [[Enumerable]]: false, [[Configurable]]: false}).
The abstract operation SetFunctionName requires a Function argument F, a String or Symbol argument
+ name and optionally a String argument prefix. This operation adds a name property to
+ F by performing the following steps:
+
+
+
Assert: F is an extensible object that does not have a
+ name own property.
NOTE When an execution context is established for
+ evaluating an ECMAScript function a new function Environment Record is created and
+ bindings for each formal parameter are instantiated in that Environment Record.
+ Each declaration in the function body is also instantiated. If the function’s formal parameters do not include any
+ default value initializers then the body declarations are instantiated in the same Environment Record as the parameters. If default value parameter initializers exist, a
+ second Environment Record is created for the body declarations. Formal parameters
+ and functions are initialized as part of FunctionDeclarationInstantiation. All other bindings are initialized during
+ evaluation of the function body.
+
+
+
FunctionDeclarationInstantiation is performed as follows using arguments func and argumentsList.
+ func is the function object for which the execution context is being
+ established.
For each d in varDeclarations, in reverse list order do
+
+
If d is neither a VariableDeclaration or a ForBinding, then
+
+
Assert: d is either a FunctionDeclaration or a
+ GeneratorDeclaration.
+
Let fn be the sole element of the BoundNames of d.
+
If fn is not an element of functionNames, then
+
+
Insert fn as the first element of functionNames.
+
NOTE If there are multiple FunctionDeclarations or
+ GeneratorDeclarations for the same name, the last declaration is used.
+
Insert d as the first element of functionsToInitialize.
+
+
+
+
+
+
+
Let argumentsObjectNeeded be true.
+
If the value of the [[ThisMode]] internal slot of
+ func is lexical, then
+
+
NOTE Arrow functions never have an arguments objects.
+
Let argumentsObjectNeeded be false.
+
+
+
Else if "arguments" is an element of parameterNames, then
+
+
Let argumentsObjectNeeded be false.
+
+
+
Else if hasParameterExpressions is false, then
+
+
If "arguments" is an element of functionNames or if "arguments" is an element of
+ lexicalNames, then
+
+
Let argumentsObjectNeeded be false.
+
+
+
+
+
For each String paramName in parameterNames, do
+
+
Let alreadyDeclared be envRec.HasBinding(paramName).
+
NOTE Early errors ensure that duplicate parameter names can only occur in non-strict functions that do not have
+ parameter default values or rest parameters.
+
If alreadyDeclared is false, then
+
+
Let status be envRec.CreateMutableBinding(paramName).
+
If hasDuplicates is true, then
+
+
Let status be envRec.InitializeBinding(paramName, undefined).
NOTE mapped argument object is only provided for non-strict functions that don’t have a rest parameter,
+ any parameter default value initializers, or any destructured parameters .
NOTE A separate Environment Record is needed to ensure that closures
+ created by expressions in the formal parameter list do not have visibility of declarations in the function
+ body.
NOTE: Non-strict functions use a separate lexical Environment Record for
+ top-level lexical declarations so that a direct eval (see 12.3.4.1) can determine whether any var scoped
+ declarations introduced by the eval code conflict with pre-existing top-level lexically scoped declarations. This
+ is not needed for strict functions because a strict direct eval always places all declarations into a
+ new Environment Record.
Let lexDeclarations be the LexicallyScopedDeclarations of code.
+
For each element d in lexDeclarations do
+
+
NOTE A lexically declared name cannot be the same as a function/generator declaration, formal parameter, or a var
+ name. Lexically declared names are only instantiated here but not initialized.
+
For each element dn of the BoundNames of d do
+
+
If IsConstantDeclaration of d is true, then
+
+
Let status be lexEnvRec.CreateImmutableBinding(dn, true).
+
+
+
Else,
+
+
Let status be lexEnvRec.CreateMutableBinding(dn, false).
NOTE 1B.3.3 provides an extension to the
+ above algorithm that is necessary for backwards compatibility with web browser implementations of ECMAScript that predate
+ the sixth edition of ECMA-262.
+
+
+
+
NOTE 2 Parameter Initializers may contain direct eval expressions (12.3.4.1). Any top level declarations of such evals are only
+ visible to the eval code (10.2). The creation of the environment for such
+ declarations is described in 14.1.18.
The built-in function objects defined in this specification may be implemented as either ECMAScript function objects (9.2) whose behaviour is provided using ECMAScript code or as implementation
+ provided exotic function objects whose behaviour is provided in some other manner. In either case, the effect of calling
+ such functions must conform to their specifications. An implementation may also provide additional built-in function objects
+ that are not defined in this specification.
+
+
If a built-in function object is implemented as an exotic object it must have the ordinary object behaviour specified in
+ 9.1. All such exotic function objects also have
+ [[Prototype]], [[Extensible]], and [[Realm]] internal slots.
+
+
Unless otherwise specified every built-in function object has the %FunctionPrototype% object (19.2.3) as the initial value of its [[Prototype]] internal slot.
+
+
The behaviour specified for each built-in function via algorithm steps or other means is the specification of the
+ function body behaviour for both [[Call]] and [[Construct]] invocations of the function. However, [[Construct]] invocation
+ is not supported by all built-in functions. For each built-in function, when invoked with [[Call]], the [[Call]]
+ thisArgument provides the this value, the [[Call]] argumentsList provides
+ the named parameters, and the NewTarget value is undefined. When invoked with [[Construct]], the
+ this value is uninitialized, the [[Construct]] argumentsList provides the named
+ parameters, and the [[Construct]] newTarget parameter provides the NewTarget value. If the built-in function is
+ implemented as an ECMAScript function object then this specified behaviour
+ must be implemented by the ECMAScript code that is the body of the function. Built-in functions that are ECMAScript function
+ objects must be strict mode functions. If a built-in constructor has any [[Call]] behaviour other than throwing a TypeError exception, an ECMAScript implementation of the function must be done in a manner that does
+ not cause the function’s [[FunctionKind]] internal slot
+ to have the value "classConstructor".
+
+
Built-in function objects that are not identified as constructors do not implement the [[Construct]] internal method
+ unless otherwise specified in the description of a particular function. When a built-in constructor is called as part of a
+ new expression the argumentsList parameter of the invoked [[Construct]] internal method provides the
+ values for the built-in constructor’s named parameters.
+
+
Built-in functions that are not constructors do not have a prototype property unless otherwise specified in
+ the description of a particular function.
+
+
If a built-in function object is not implemented as an ECMAScript function it must provide [[Call]] and [[Construct]]
+ internal methods that conform to the following definitions:
The [[Call]] internal method for a built-in function object F is called with parameters
+ thisArgument and argumentsList, a List of ECMAScript language values. The following steps are taken:
Let result be the Completion Record that is the result
+ of evaluating F in an implementation defined manner that conforms to the specification of F.
+ thisArgument is the this value, argumentsList provides the named parameters, and the NewTarget
+ value is undefined.
NOTE 1 When calleeContext is removed from the
+ execution context stack it must not be destroyed if it has been suspended and
+ retained by an accessible generator object for later resumption.
The [[Construct]] internal method for built-in function object F is called with parameters
+ argumentsList and newTarget. The steps performed are the same as [[Call]] (see 9.3.1) except that step 9 is replaced by:
+
+
+
Let result be the Completion Record that is the result
+ of evaluating F in an implementation defined manner that conforms to the specification of F. The
+ this value is uninitialized, argumentsList provides the named parameters, and newTarget provides
+ the NewTarget value.
The abstract operation CreateBuiltinFunction takes arguments realm,
+ prototype, and steps. The optional argument internalSlotsList is a List of the names of additional internal slots that must be defined as
+ part of the object. If the list is not provided, an empty List is
+ used. CreateBuiltinFunction returns a built-in function object created by the following steps:
Assert: steps is either a set of algorithm steps or other definition
+ of a functions behaviour provided in this specification.
+
Let func be a new built-in function object that when called performs the action described by steps. The
+ new function object has internal slots whose names are the elements of internalSlotsList. The initial value of
+ each of those internal slots is undefined.
Set the [[Prototype]] internal slot of func to
+ prototype.
+
Return func.
+
+
+
Each built-in function defined in this specification is created as if by calling the CreateBuiltinFunction abstract
+ operation, unless otherwise specified.
+
+
+
+
+
+
9.4 Built-in Exotic Object Internal Methods and Slots
+
+
This specification defines several kinds of built-in exotic objects. These objects generally behave similar to ordinary
+ objects except for a few specific situations. The following exotic objects use the ordinary object internal methods except
+ where it is explicitly specified otherwise below:
A bound function is an exotic object that wraps another function object. A bound function is callable (it has a
+ [[Call]] internal method and may have a [[Construct]] internal method). Calling a bound function generally results in a
+ call of its wrapped function.
+
+
Bound function objects do not have the internal slots of ECMAScript function objects defined in Table 27. Instead they have the internal slots defined in Table 28.
+
+
+ Table 28 — Internal Slots of Exotic Bound Function Objects
+
+
+
Internal Slot
+
Type
+
Description
+
+
+
[[BoundTargetFunction]]
+
Callable Object
+
The wrapped function object.
+
+
+
[[BoundThis]]
+
Any
+
The value that is always passed as the this value when calling the wrapped function.
A list of values whose elements are used as the first arguments to any call to the wrapped function.
+
+
+
+
+
Unlike ECMAScript function objects, bound function objects do not use an alternative definition of the
+ [[GetOwnProperty]] internal methods. Bound function objects provide all of the essential internal methods as specified in
+ 9.1. However, they use the following definitions
+ for the essential internal methods of function objects.
When the [[Call]] internal method of an exotic bound function object,
+ F, which was created using the bind function is called with parameters thisArgument and
+ argumentsList, a List of ECMAScript language values, the following steps are taken:
Let args be a new list containing the same values as the list boundArgs in the same order followed by
+ the same values as the list argumentsList in the same order.
When the [[Construct]] internal method of an exotic bound function
+ object, F that was created using the bind function is called with a list of arguments argumentsList and newTarget, the following steps are taken:
Let args be a new list containing the same values as the list boundArgs in the same order followed by
+ the same values as the list argumentsList in the same order.
+
If SameValue(F, newTarget) is true, let newTarget be
+ target.
The abstract operation BoundFunctionCreate with arguments targetFunction, boundThis and
+ boundArgs is used to specify the creation of new Bound
+ Function exotic objects. It performs the following steps:
An Array object is an exotic object that gives special treatment to array index property keys (see 6.1.7). A property whose property name is an array index is also called an element.
+ Every Array object has a length property whose value is always a nonnegative integer less than 232. The value of the length property is numerically
+ greater than the name of every own property whose name is an array index; whenever an own property of an Array object is
+ created or changed, other properties are adjusted as necessary to maintain this invariant. Specifically, whenever an own
+ property is added whose name is an array index, the value of the length property is changed, if necessary, to
+ be one more than the numeric value of that array index; and whenever the value of the length property is
+ changed, every own property whose name is an array index whose value is not smaller than the new length is deleted. This
+ constraint applies only to own properties of an Array object and is unaffected by length or array index
+ properties that may be inherited from its prototypes.
+
+
+
NOTE A String property name P is an array index if and only if ToString(ToUint32(P)) is equal to P and ToUint32(P) is not equal to 232−1.
+
+
+
Array exotic objects always have a non-configurable property named "length".
+
+
Array exotic objects provide an alternative definition for the [[DefineOwnProperty]] internal method. Except for that
+ internal method, Array exotic objects provide all of the other essential internal methods as specified in 9.1.
Assert: oldLenDesc will never be undefined or an accessor
+ descriptor because Array objects are created with a length data property that cannot be deleted or
+ reconfigured.
The abstract operation ArrayCreate with argument length (a positive integer) and optional argument
+ proto is used to specify the creation of new Array exotic objects. It performs the following steps:
The abstract operation ArraySpeciesCreate with arguments originalArray and length is used to
+ specify the creation of a new Array object using a constructor function that is derived from originalArray. It
+ performs the following steps:
NOTE If originalArray was created using the standard built-in Array constructor for a
+ Realm that is not the Realm of the running execution context, then a new Array is created using the Realm of the running execution context. This maintains
+ compatibility with Web browsers that have historically had that behaviour for the Array.prototype methods that now are
+ defined using ArraySpeciesCreate.
Assert: oldLenDesc will never be undefined or an accessor
+ descriptor because Array objects are created with a length data property that cannot be deleted or
+ reconfigured.
Return OrdinaryDefineOwnProperty(A, "length",
+ PropertyDescriptor{[[Writable]]: false}). This call will always return true.
+
+
+
Return true.
+
+
+
+
NOTE In steps 3 and 4, if Desc.[[Value]] is an object then its valueOf
+ method is called twice. This is legacy behaviour that was specified with this effect starting with the 2nd
+ Edition of this specification.
A String object is an exotic object that encapsulates a String value and exposes virtual integer indexed data
+ properties corresponding to the individual code unit elements of the string value. Exotic String objects always have a
+ data property named "length" whose value is the number of code unit elements in the encapsulated String
+ value. Both the code unit data properties and the "length" property are non-writable and
+ non-configurable.
+
+
Exotic String objects have the same internal slots as ordinary objects. They also have a [[StringData]] internal
+ slot.
+
+
Exotic String objects provide alternative definitions for the following internal methods. All of the other exotic
+ String object essential internal methods that are not defined below are as specified in 9.1.
The abstract operation StringCreate with arguments value and prototype is used to specify the
+ creation of new exotic String objects. It performs the following steps:
Most ECMAScript functions make an arguments objects available to their code. Depending upon the characteristics of the
+ function definition, its argument object is either an ordinary object or an arguments exotic object. An arguments
+ exotic object is an exotic object whose array index properties map to the formal parameters bindings of an invocation of
+ its associated ECMAScript function.
+
+
Arguments exotic objects have the same internal slots as ordinary objects. They also have a [[ParameterMap]] internal
+ slot. Ordinary arguments objects also have a [[ParameterMap]] internal slot whose value is always undefined. For ordinary
+ argument objects the [[ParameterMap]] internal slot is only used by Object.prototype.toString (19.1.3.6) to identify them as such.
+
+
Arguments exotic objects provide alternative definitions for the following internal methods. All of the other exotic
+ arguments object essential internal methods that are not defined below are as specified in 9.1
+
+
+
NOTE 1 For non-strict functions the integer indexed data properties of an arguments object
+ whose numeric name values are less than the number of formal parameters of the corresponding function object initially
+ share their values with the corresponding argument bindings in the function’s execution context. This means that changing the property changes the corresponding
+ value of the argument binding and vice-versa. This correspondence is broken if such a property is deleted and then
+ redefined or if the property is changed into an accessor property. For strict mode functions, the values of the
+ arguments object’s properties are simply a copy of the arguments passed to the function and there is no dynamic
+ linkage between the property values and the formal parameter values.
+
+
+
+
NOTE 2 The ParameterMap object and its property values are used as a device for specifying
+ the arguments object correspondence to argument bindings. The ParameterMap object and the objects that are the values of
+ its properties are not directly observable from ECMAScript code. An ECMAScript implementation does not need to actually
+ create or use such objects to implement the specified semantics.
+
+
+
+
NOTE 3 Arguments objects for strict mode functions define non-configurable accessor
+ properties named "caller" and "callee" which throw a TypeError exception on access. The
+ "callee" property has a more specific meaning for non-strict functions and a "caller" property
+ has historically been provided as an implementation-defined extension by some ECMAScript implementations. The strict
+ mode definition of these properties exists to ensure that neither of them is defined in any other manner by conforming
+ ECMAScript implementations.
The [[DefineOwnProperty]] internal method of an arguments exotic object when called with a property keyP and Property
+ DescriptorDesc performs the following steps:
+
+
+
Let args be the arguments object.
+
Let map be the value of the [[ParameterMap]] internal slot of the arguments object.
The [[Get]] internal method of an arguments exotic object when called with a property
+ keyP and ECMAScript language valueReceiver performs the following steps:
+
+
+
Let args be the arguments object.
+
Let map be the value of the [[ParameterMap]] internal slot of the arguments object.
The [[Set]] internal method of an arguments exotic object when called with property key
+ P, value V, and ECMAScript language valueReceiver performs the following steps:
Let result be the result of calling the default [[Delete]] internal method for ordinary objects (9.1.10) on the arguments object passing
+ P as the argument.
The abstract operation CreateMappedArgumentsObject is called with
+ object func, parsed grammar phrase formals, ListargumentsList, and Environment Recordenv. The
+ following steps are performed:
+
+
+
Assert: formals does not contain a rest parameter, any binding
+ patterns, or any initializers. It may contain duplicate identifiers.
+
Let len be the number of elements in argumentsList.
+
Let obj be a newly created arguments exotic object with a [[ParameterMap]] internal slot.
+
Set the [[GetOwnProperty]] internal method of obj as specified in 9.4.4.1.
+
Set the [[DefineOwnProperty]] internal method of obj as specified in 9.4.4.2.
+
Set the [[Get]] internal method of obj as specified in 9.4.4.3.
+
Set the [[Set]] internal method of obj as specified in 9.4.4.4.
+
Set the [[Delete]] internal method of obj as specified in 9.4.4.5.
+
Set the remainder of obj’s essential internal methods to the default ordinary object definitions
+ specified in 9.1.
+
Set the [[Prototype]] internal slot of obj to
+ %ObjectPrototype%.
+
Set the [[Extensible]] internal slot of obj
+ to true.
+
Let parameterNames be the BoundNames of formals.
+
Let numberOfParameters be the number of elements in parameterNames
The abstract operation MakeArgGetter called with String
+ name and Environment Recordenv creates a built-in function
+ object that when executed returns the value bound for name in env. It performs the following
+ steps:
An ArgGetter function is an anonymous built-in function with [[name]] and [[env]] internal slots. When an ArgGetter
+ function f that expects no arguments is called it performs the following steps:
+
+
+
Let name be the value of f’s [[name]] internal slot.
The abstract operation MakeArgSetter called with String
+ name and Environment Recordenv creates a built-in function
+ object that when executed sets the value bound for name in env. It performs the following
+ steps:
An ArgSetter function is an anonymous built-in function with [[name]] and [[env]] internal slots. When an ArgSetter
+ function f is called with argument value it performs the following steps:
+
+
+
Let name be the value of f’s [[name]] internal slot.
An Integer Indexed object is an exotic object that performs special handling of integer index property keys.
+
+
Integer Indexed exotic objects have the same internal slots as ordinary objects additionally [[ViewedArrayBuffer]],
+ [[ArrayLength]], [[ByteOffset]], and [[TypedArrayName]] internal slots.
+
+
Integer Indexed Exotic objects provide alternative definitions for the following internal methods. All of the other
+ Integer Indexed exotic object essential internal methods that are not defined below are as specified in 9.1.
When the [[DefineOwnProperty]] internal method of an Integer Indexed exotic object O is called with property keyP, and Property
+ DescriptorDesc the following steps are taken:
When the [[Get]] internal method of an Integer Indexed exotic object O is called with property keyP and ECMAScript language
+ valueReceiver the following steps are taken:
When the [[Set]] internal method of an Integer Indexed exotic object O is called with property keyP, value V, and ECMAScript language valueReceiver, the following steps
+ are taken:
The abstract operation IntegerIndexedObjectCreate with arguments prototype and internalSlotsList
+ is used to specify the creation of new Integer Indexed exotic objects. The argument internalSlotsList is a List of the names of additional internal slots that must be defined as
+ part of the object. IntegerIndexedObjectCreate performs the following steps:
+
+
+
Let A be a newly created object with an internal
+ slot for each name in internalSlotsList.
+
Set A’s essential internal methods to the default ordinary object definitions specified in 9.1.
+
Set the [[GetOwnProperty]] internal method of A as specified in 9.4.5.1.
+
Set the [[HasProperty]] internal method of A as specified in 9.4.5.2.
+
Set the [[DefineOwnProperty]] internal method of A as specified in 9.4.5.3.
+
Set the [[Get]] internal method of A as specified in 9.4.5.4.
+
Set the [[Set]] internal method of A as specified in 9.4.5.5.
+
Set the [[OwnPropertyKeys]] internal method of A as specified in 9.4.5.6.
+
Set the [[Prototype]] internal slot of A to
+ prototype.
+
Set the [[Extensible]] internal slot of A to
+ true.
A module namespace object is an exotic object that exposes the bindings exported from an ECMAScript Module(See 15.2.3). There is a one-to-one correspondence between
+ the String-keyed own properties of a module namespace exotic object and the binding names exported by the Module. The exported bindings include any bindings that are indirectly exported using export
+ * export items. Each String-valued own property key is the StringValue of the
+ corresponding exported binding name. These are the only String-keyed properties of a module namespace exotic object. Each
+ such property has the attributes {[[Configurable]]: false, [[Enumerable]]: true}. Module namespace objects are not extensible.
+
+
Module namespace objects have the internal slots defined in Table 29.
A List containing the String values of the exported names exposed as own properties of this object. The list is ordered as if an Array of those string values had been sorted using Array.prototype.sort using SortCompare as comparefn.
+
+
+
+
+
Module namespace exotic objects provide alternative definitions for all of the internal methods.
When the [[DefineOwnProperty]] internal method of a module namespace exotic object O is called with property keyP and Property
+ DescriptorDesc, the following steps are taken:
When the [[Get]] internal method of a module namespace exotic object O is called with property keyP and ECMAScript language
+ valueReceiver the following steps are taken:
NOTEResolveExport is idempotent and side-effect free. An
+ implementation might choose to pre-compute or cache the ResolveExport results for the
+ [[Exports]] of each module namespace exotic object.
When the [[Set]] internal method of a module namespace exotic object
+ O is called with property keyP, value V, and ECMAScript language valueReceiver, the following steps
+ are taken:
The abstract operation ModuleNamespaceCreate with arguments module, and exports is used to
+ specify the creation of new module namespace exotic objects. It performs the following steps:
Create own properties of M corresponding to the definitions in 26.3.
+
Set module.[[Namespace]] to M.
+
Return M.
+
+
+
+
+
+
+
+
9.5 Proxy Object Internal Methods and Internal Slots
+
+
A proxy object is an exotic object whose essential internal methods are partially implemented using ECMAScript code.
+ Every proxy objects has an internal slot called
+ [[ProxyHandler]]. The value of [[ProxyHandler]] is an object, called the proxy’s handler object, or null. Methods (see Table 30) of a handler object may be used to augment the
+ implementation for one or more of the proxy object’s internal methods. Every proxy object also has an internal slot called [[ProxyTarget]] whose value is either an
+ object or the null value. This object is called the proxy’s target object.
+
+
+ Table 30 — Proxy Handler Methods
+
+
+
Internal Method
+
Handler Method
+
+
+
[[GetPrototypeOf]]
+
getPrototypeOf
+
+
+
[[SetPrototypeOf]]
+
setPrototypeOf
+
+
+
[[IsExtensible]]
+
isExtensible
+
+
+
[[PreventExtensions]]
+
preventExtensions
+
+
+
[[GetOwnProperty]]
+
getOwnPropertyDescriptor
+
+
+
[[HasProperty]]
+
has
+
+
+
[[Get]]
+
get
+
+
+
[[Set]]
+
set
+
+
+
[[Delete]]
+
deleteProperty
+
+
+
[[DefineOwnProperty]]
+
defineProperty
+
+
+
[[Enumerate]]
+
enumerate
+
+
+
[[OwnPropertyKeys]]
+
ownKeys
+
+
+
[[Call]]
+
apply
+
+
+
[[Construct]]
+
construct
+
+
+
+
+
When a handler method is called to provide the implementation of a proxy object internal method, the handler method is
+ passed the proxy’s target object as a parameter. A proxy’s handler object does not necessarily have a method
+ corresponding to every essential internal method. Invoking an internal method on the proxy results in the invocation of the
+ corresponding internal method on the proxy’s target object if the handler object does not have a method corresponding
+ to the internal trap.
+
+
The [[ProxyHandler]] and [[ProxyTarget]] internal slots of a proxy object are always initialized when the object is
+ created and typically may not be modified. Some proxy objects are created in a manner that permits them to be subsequently
+ revoked. When a proxy is revoked, its [[ProxyHander]] and [[ProxyTarget]] internal slots are set to null
+ causing subsequent invocations of internal methods on that proxy object to throw a TypeError
+ exception.
+
+
Because proxy objects permit the implementation of internal methods to be provided by arbitrary ECMAScript code, it is
+ possible to define a proxy object whose handler methods violates the invariants defined in 6.1.7.3. Some of the internal method invariants defined in 6.1.7.3 are essential integrity invariants. These invariants
+ are explicitly enforced by the proxy object internal methods specified in this section. An ECMAScript implementation must be
+ robust in the presence of all possible invariant violations.
If SameValue(handlerProto, targetProto) is false, throw a
+ TypeError exception.
+
Return handlerProto.
+
+
+
+
NOTE [[GetPrototypeOf]] for proxy objects enforces the following invariant:
+
+
+
+
The result of [[GetPrototypeOf]] must be either an Object or null.
+
+
+
+
If the target object is not extensible, [[GetPrototypeOf]] applied to the proxy object must return the same value
+ as [[GetPrototypeOf]] applied to the proxy object’s target object.
If SameValue(booleanTrapResult, targetResult) is false, throw a
+ TypeError exception.
+
Return booleanTrapResult.
+
+
+
+
NOTE [[IsExtensible]] for proxy objects enforces the following invariant:
+
+
+
+
The result of [[IsExtensible]] is a Boolean value.
+
+
+
+
[[IsExtensible]] applied to the proxy object must return the same value as [[IsExtensible]] applied to the proxy
+ object’s target object with the same argument.
If targetDesc is undefined or targetDesc.[[Configurable]] is true, then
+
+
Throw a TypeError exception.
+
+
+
+
+
Return resultDesc.
+
+
+
+
NOTE [[GetOwnProperty]] for proxy objects enforces the following invariants:
+
+
+
+
The result of [[GetOwnProperty]] must be either an Object or undefined.
+
+
+
+
A property cannot be reported as non-existent, if it exists as a non-configurable own property of the target
+ object.
+
+
+
+
A property cannot be reported as non-existent, if it exists as an own property of the target object and the target
+ object is not extensible.
+
+
+
+
A property cannot be reported as existent, if it does not exists as an own property of the target object and the
+ target object is not extensible.
+
+
+
+
A property cannot be reported as non-configurable, if it does not exists as an own property of the target object or
+ if it exists as a configurable own property of the target object.
When the [[DefineOwnProperty]] internal method of a Proxy exotic object O is called with property keyP and Property
+ DescriptorDesc, the following steps are taken:
If settingConfigFalse is true and targetDesc.[[Configurable]] is true, throw a
+ TypeError exception.
+
+
+
Return true.
+
+
+
+
NOTE [[DefineOwnProperty]] for proxy objects enforces the following invariants:
+
+
+
+
The result of [[DefineOwnProperty]] is a Boolean value.
+
+
+
+
A property cannot be added, if the target object is not extensible.
+
+
+
+
A property cannot be non-configurable, unless there exists a corresponding non-configurable own property of the
+ target object.
+
+
+
+
If a property has a corresponding target object property then applying the Property Descriptor of the property to the target object using
+ [[DefineOwnProperty]] will not throw an exception.
When the [[Get]] internal method of a Proxy exotic object O is called with property
+ keyP and ECMAScript language valueReceiver the following steps are taken:
If IsDataDescriptor(targetDesc) and targetDesc.[[Configurable]]
+ is false and targetDesc.[[Writable]] is false, then
+
+
If SameValue(trapResult, targetDesc.[[Value]]) is false,
+ throw a TypeError exception.
+
+
+
If IsAccessorDescriptor(targetDesc) and
+ targetDesc.[[Configurable]] is false and targetDesc.[[Get]] is undefined, then
+
+
If trapResult is not undefined, throw a TypeError exception.
+
+
+
+
+
Return trapResult.
+
+
+
+
NOTE [[Get]] for proxy objects enforces the following invariants:
+
+
+
+
The value reported for a property must be the same as the value of the corresponding target object property if the
+ target object property is a non-writable, non-configurable own data property.
+
+
+
+
The value reported for a property must be undefined if the corresponding target object property is a
+ non-configurable own accessor property that has undefined as its [[Get]] attribute.
When the [[Set]] internal method of a Proxy exotic object O is called with property
+ keyP, value V, and ECMAScript language valueReceiver, the following steps are taken:
If IsDataDescriptor(targetDesc) and targetDesc.[[Configurable]]
+ is false and targetDesc.[[Writable]] is false, then
+
+
If SameValue(V, targetDesc.[[Value]]) is false, throw a
+ TypeError exception.
+
+
+
If IsAccessorDescriptor(targetDesc) and
+ targetDesc.[[Configurable]] is false, then
+
+
If targetDesc.[[Set]] is undefined, throw a TypeError exception.
+
+
+
+
+
Return true.
+
+
+
+
NOTE [[Set]] for proxy objects enforces the following invariants:
+
+
+
+
The result of [[Set]] is a Boolean value.
+
+
+
+
Cannot change the value of a property to be different from the value of the corresponding target object property if
+ the corresponding target object property is a non-writable, non-configurable own data property.
+
+
+
+
Cannot set the value of a property if the corresponding target object property is a non-configurable own accessor
+ property that has undefined as its [[Set]] attribute.
The Type of each result List element is either String or
+ Symbol.
+
+
+
+
The result List must contain the keys of all non-configurable
+ own properties of the target object.
+
+
+
+
If the target object is not extensible, then the result List
+ must contain all the keys of the own properties of the target object and no other values.
The [[Call]] internal method of a Proxy exotic object O is called with parameters thisArgument and
+ argumentsList, a List of ECMAScript language values. The following steps are taken:
+
+
+
Let handler be the value of the [[ProxyHandler]] internal slot of O.
NOTE A Proxy exotic object only has a [[Call]] internal method if the initial value of its
+ [[ProxyTarget]] internal slot is an object that has a
+ [[Call]] internal method.
The [[Construct]] internal method of a Proxy exotic object O is called with parameters
+ argumentsList which is a possibly empty List of ECMAScript language values and newTarget. The following steps are
+ taken:
+
+
+
Let handler be the value of the [[ProxyHandler]] internal slot of O.
If Type(newObj) is not Object, throw a TypeError
+ exception.
+
Return newObj.
+
+
+
+
NOTE 1 A Proxy exotic object only has a [[Construct]] internal method if the initial value of
+ its [[ProxyTarget]] internal slot is an object that has a
+ [[Construct]] internal method.
+
+
+
+
NOTE 2 [[Construct]] for proxy objects enforces the following invariants:
The abstract operation ProxyCreate with arguments target and handler is used to specify the
+ creation of new Proxy exotic objects. It performs the following steps:
+
+
+
If Type(target) is not Object, throw a TypeError
+ Exception.
+
If target is a Proxy exotic object and the value of the [[ProxyHandler]] internal slot of target is null, throw a
+ TypeError exception.
+
If Type(handler) is not Object, throw a TypeError
+ Exception.
+
If handler is a Proxy exotic object and the value of the [[ProxyHandler]] internal slot of handler is null, throw a
+ TypeError exception.
+
Let P be a newly created object.
+
Set P’s essential internal methods (except for [[Call]] and [[Construct]]) to the definitions specified
+ in 9.5.
ECMAScript code is expressed using Unicode, version 5.1 or later. ECMAScript source text is a sequence of code points.
+ All Unicode code point values from U+0000 to U+10FFFF, including surrogate code points, may occur in source text where
+ permitted by the ECMAScript grammars. The actual encodings used to store and interchange ECMAScript source text is not
+ relevant to this specification. Regardless of the external source text encoding, a conforming ECMAScript implementation
+ processes the source text as if it was an equivalent sequence of SourceCharacter values. Each SourceCharacter being a Unicode code point. Conforming ECMAScript implementations are not required to
+ perform any normalization of source text, or behave as though they were performing normalization of source text.
+
+
The components of a combining character sequence are treated as individual Unicode code points even though a user might
+ think of the whole sequence as a single character.
+
+
+
NOTE In string literals, regular expression literals, template literals and identifiers, any
+ Unicode code point may also be expressed using Unicode escape sequences that explicitly express a code point’s
+ numeric value. Within a comment, such an escape sequence is effectively ignored as part of the comment.
+
+
ECMAScript differs from the Java programming language in the behaviour of Unicode escape sequences. In a Java program,
+ if the Unicode escape sequence \u000A, for example, occurs within a single-line comment, it is interpreted as
+ a line terminator (Unicode code point U+000A is line feed (lf)) and therefore the next code point is not part of the
+ comment. Similarly, if the Unicode escape sequence \u000A occurs within a string literal in a Java program,
+ it is likewise interpreted as a line terminator, which is not allowed within a string literal—one must write
+ \n instead of \u000A to cause a line feed (lf) to be part of the string value of a string
+ literal. In an ECMAScript program, a Unicode escape sequence occurring within a comment is never interpreted and therefore
+ cannot contribute to termination of the comment. Similarly, a Unicode escape sequence occurring within a string literal in
+ an ECMAScript program always contributes to the literal and is never interpreted as a line terminator or as a code point
+ that might terminate the string literal.
Global code is source text that is treated as an ECMAScript Script. The global code of a particular
+ Script does not include any source text that is parsed as part of a FunctionDeclaration,
+ FunctionExpression, GeneratorDeclaration, GeneratorExpression, MethodDefinition,
+ ArrowFunction, ClassDeclaration, or ClassExpression.
+
+
+
+
Eval code is the source text supplied to the built-in eval function. More precisely, if the
+ parameter to the built-in eval function is a String, it is treated as an ECMAScript Script. The eval
+ code for a particular invocation of eval is the global code portion of that Script.
+
+
+
+
Function code is source text that is parsed to supply the value of the [[ECMAScriptCode]] and
+ [[FormalParameters]] internal slots (see 9.2) of an ECMAScript function object. The function code of a particular ECMAScript
+ function does not include any source text that is parsed as the function code of a nested FunctionDeclaration,
+ FunctionExpression, GeneratorDeclaration, GeneratorExpression, MethodDefinition,
+ ArrowFunction, ClassDeclaration, or ClassExpression.
+
+
+
+
Module code is source text that is code that is provided as a ModuleBody. It is the code that is
+ directly evaluated when a module is initialized. The module code of a particular module does not include any source text
+ that is parsed as part of a nested FunctionDeclaration, FunctionExpression, GeneratorDeclaration,
+ GeneratorExpression, MethodDefinition, ArrowFunction, ClassDeclaration, or
+ ClassExpression.
+
+
+
+
+
NOTE Function code is generally provided as the bodies of Function Definitions (14.1), Arrow Function Definitions (14.2), Method Definitions (14.3) and
+ Generator Definitions (14.4). Function code is also derived from the
+ arguments to the Function constructor (19.2.1.1) and the
+ GeneratorFunction constructor (25.2.1.1).
An ECMAScript Script syntactic unit may be processed using either unrestricted or strict mode
+ syntax and semantics. Code is interpreted as strict mode code in the following situations:
All parts of a ClassDeclaration or a ClassExpression are strict mode
+ code.
+
+
+
+
Eval code is strict mode code if it begins with a Directive Prologue that contains a Use Strict Directive or if the call to eval is a direct
+ eval (see 12.3.4.1) that is contained in strict mode
+ code.
+
+
+
+
Function code is strict mode code if the associated FunctionDeclaration, FunctionExpression, GeneratorDeclaration, GeneratorExpression, MethodDefinition, or ArrowFunction is contained in strict mode code or if the code that produces the value of the
+ function’s [[ECMAScriptCode]] internal slot begins
+ with a Directive Prologue that contains a Use Strict Directive.
+
+
+
+
Function code that is supplied as the arguments to the built-in Function and Generator
+ constructors is strict mode code if the last argument is a String that when processed has a FunctionBody begins with a Directive
+ Prologue that contains a Use Strict
+ Directive.
+
+
+
+
ECMAScript code that is not strict mode code is called non-strict code.
An ECMAScript implementation may support the evaluation of exotic function objects whose evaluative behaviour is
+ expressed in some implementation defined form of executable code other than via ECMAScript code. Whether a function object
+ is an ECMAScript code function or a non-ECMAScript function is not semantically observable from the perspective of an
+ ECMAScript code function that calls or is called by such a non-ECMAScript function.
The source text of an ECMAScript Script or Module is first converted into a
+ sequence of input elements, which are tokens, line terminators, comments, or white space. The source text is scanned from left
+ to right, repeatedly taking the longest possible sequence of code points as the next input element.
+
+
There are several situations where the identification of lexical input elements is sensitive to the syntactic grammar
+ context that is consuming the input elements. This requires multiple goal symbols for the lexical grammar. The InputElementRegExpOrTemplateTail goal is used in syntactic grammar contexts where a
+ RegularExpressionLiteral, a TemplateMiddle, or a TemplateTail is permitted. The
+ InputElementRegExp goal symbol is used in all syntactic grammar contexts where a RegularExpressionLiteral is permitted but neither a TemplateMiddle, nor a TemplateTail is permitted. The InputElementTemplateTail goal is used in all
+ syntactic grammar contexts where a TemplateMiddle or a TemplateTail is
+ permitted but a RegularExpressionLiteral is not permitted. In all other contexts, InputElementDiv is used as the lexical goal symbol.
+
+
+
NOTE The use of multiple lexical goals ensures that there are no lexical ambiguities that would
+ affect automatic semicolon insertion. For example, there are no syntactic
+ grammar contexts where both a leading division or division-assignment, and a leading RegularExpressionLiteral are
+ permitted. This is not affected by semicolon insertion (see 11.9); in
+ examples such as the following:
+
+
a = b /hi/g.exec(c).map(d);
+
+
where the first non-whitespace, non-comment code point after a LineTerminator is U+002F (SOLIDUS) and the
+ syntactic context allows division or division-assignment, no semicolon is inserted at the LineTerminator. That is,
+ the above example is interpreted in the same way as:
The Unicode format-control characters (i.e., the characters in category “Cf” in the Unicode Character Database
+ such as left-to-right mark or right-to-left mark) are control codes used to control the formatting of a range of text in the
+ absence of higher-level protocols for this (such as mark-up languages).
+
+
It is useful to allow format-control characters in source text to facilitate editing and display. All format control
+ characters may be used within comments, and within string literals, template literals, and regular expression literals.
+
+
U+200C (Zero width non-joiner) and U+200D (Zero width joiner) are format-control characters that are used to make necessary distinctions when forming words or phrases
+ in certain languages. In ECMAScript source text these code points may also be used in an IdentifierName (see 11.6.1) after the first character.
+
+
U+FEFF (Zero Width no-break space) is a format-control character used primarily at the start of a text to mark it as Unicode and to allow
+ detection of the text's encoding and byte order. <ZWNBSP> characters
+ intended for this purpose can sometimes also appear after the start of a text, for example as a result of concatenating files.
+ In ECMAScript source text <ZWNBSP> code points are treated as white space characters (see
+ 11.2).
+
+
The special treatment of certain format-control characters outside of comments, string literals, and regular expression
+ literals is summarized in Table 31.
White space code points are used to improve source text readability and to separate tokens (indivisible lexical units) from
+ each other, but are otherwise insignificant. White space code points may occur between any two tokens and at the start or end
+ of input. White space code points may occur within a StringLiteral, a RegularExpressionLiteral, a Template, or a TemplateSubstitutionTail where they are considered significant code points forming part of a literal value.
+ They may also occur within a Comment, but cannot appear within any other kind of token.
+
+
The ECMAScript white space code points are listed in Table 32.
+
+
+ Table 32 — White Space Code Points
+
+
+
Code Point
+
Name
+
Abbreviation
+
+
+
U+0009
+
Character Tabulation
+
<TAB>
+
+
+
U+000B
+
LINE TABULATION
+
<VT>
+
+
+
U+000C
+
Form Feed (ff)
+
<FF>
+
+
+
U+0020
+
Space
+
<SP>
+
+
+
U+00A0
+
No-break space
+
<NBSP>
+
+
+
U+FEFF
+
ZERO wIDTH nO-bREAK SPACE
+
<ZWNBSP>
+
+
+
Other category “Zs”
+
Any other Unicode “Separator, space” code point
+
<USP>
+
+
+
+
+
ECMAScript implementations must recognize as WhiteSpace code points listed in the “Separator,
+ space” (Zs) category by Unicode 5.1. ECMAScript implementations may also recognize as WhiteSpace
+ additional category Zs code points from subsequent editions of the Unicode Standard.
+
+
+
NOTE Other than for the code points listed in Table 32, ECMAScript
+ WhiteSpace intentionally excludes all code points that have the Unicode “White_Space” property but which
+ are not classified in category “Zs”.
Like white space code points, line terminator code points are used to improve source text readability and to separate
+ tokens (indivisible lexical units) from each other. However, unlike white space code points, line terminators have some
+ influence over the behaviour of the syntactic grammar. In general, line terminators may occur between any two tokens, but
+ there are a few places where they are forbidden by the syntactic grammar. Line terminators also affect the process of automatic semicolon insertion (11.9). A line terminator cannot occur within any token except a StringLiteral, Template, or TemplateSubstitutionTail. Line
+ terminators may only occur within a StringLiteral token as part of a LineContinuation.
+
+
A line terminator can occur within a MultiLineComment (11.4) but cannot
+ occur within a SingleLineComment.
+
+
Line terminators are included in the set of white space code points that are matched by the \s class in
+ regular expressions.
+
+
The ECMAScript line terminator code points are listed in Table 33.
+
+
+ Table 33 — Line Terminator Code Points
+
+
+
Code Point
+
Unicode Name
+
Abbreviation
+
+
+
U+000A
+
Line Feed (LF)
+
<LF>
+
+
+
U+000D
+
Carriage Return (CR)
+
<CR>
+
+
+
U+2028
+
Line separator
+
<LS>
+
+
+
U+2029
+
Paragraph separator
+
<PS>
+
+
+
+
+
Only the Unicode code points in Table 33 are treated as line terminators. Other new line or line
+ breaking Unicode code points are not treated as line terminators but are treated as white space if they meet the requirements
+ listed in Table 32. The sequence <CR><LF> is commonly used as a line terminator. It should
+ be considered a single SourceCharacter for the purpose of reporting line numbers.
Comments can be either single or multi-line. Multi-line comments cannot nest.
+
+
Because a single-line comment can contain any Unicode code point except a LineTerminator code
+ point, and because of the general rule that a token is always as long as possible, a single-line comment always consists of
+ all code points from the // marker to the end of the line. However, the LineTerminator at
+ the end of the line is not considered to be part of the single-line comment; it is recognized separately by the lexical
+ grammar and becomes part of the stream of input elements for the syntactic grammar. This point is very important, because it
+ implies that the presence or absence of single-line comments does not affect the process of automatic semicolon insertion (see
+ 11.9).
+
+
Comments behave like white space and are discarded except that, if a MultiLineComment contains a
+ line terminator code point, then the entire comment is considered to be a LineTerminator for purposes
+ of parsing by the syntactic grammar.
NOTE The DivPunctuator, RegularExpressionLiteral, RightBracePunctuator, and
+ TemplateSubstitutionTail productions derive additional tokens that are not included in the CommonToken
+ production.
IdentifierName and ReservedWord are tokens that are interpreted according
+ to the Default Identifier Syntax given in Unicode Standard Annex #31, Identifier and Pattern Syntax, with some small
+ modifications. ReservedWord is an enumerated subset of IdentifierName. The syntactic grammar defines Identifier as an IdentifierName that is not a ReservedWord (see
+ 11.6.2). The Unicode identifier grammar is based on character properties specified by the Unicode Standard. The Unicode
+ code points in the specified categories in version 5.1.0 of the Unicode standard must be treated as in those categories by
+ all conforming ECMAScript implementations. ECMAScript implementations may recognize identifier code points defined in later
+ editions of the Unicode Standard.
+
+
+
NOTE This standard specifies specific code point additions: U+0024 (dollar sign) and U+005F (LOW LINE) are permitted anywhere in an IdentifierName, and
+ the code pointsU+200C (zero-width non-joiner) and U+200D (zero-width joiner)
+ are permitted anywhere after the first code pointof an
+ IdentifierName.
+
+
+
Unicode escape sequences are permitted in an IdentifierName, where they contribute a single
+ Unicode code point to the IdentifierName. The code point is expressed by the HexDigits of the UnicodeEscapeSequence (see 11.8.4). The \ preceding the UnicodeEscapeSequence and the u and { } code units, if they appear, do not
+ contribute code points to the IdentifierName. A UnicodeEscapeSequence cannot
+ be used to put a code point into an IdentifierName that would otherwise be illegal. In other words,
+ if a \UnicodeEscapeSequence sequence were replaced by the SourceCharacter it contributes, the result must still be a valid IdentifierName
+ that has the exact same sequence of SourceCharacter elements as the original IdentifierName. All interpretations of IdentifierName within this specification
+ are based upon their actual code points regardless of whether or not an escape sequence was used to contribute any
+ particular code point.
+
+
Two IdentifierName that are canonically equivalent according to the Unicode standard are
+ not equal unless, after replacement of each UnicodeEscapeSequence, they are represented by
+ the exact same sequence of code points.
+
+
Syntax
+
+
+
IdentifierName::
+
IdentifierStart
+
IdentifierNameIdentifierPart
+
+
+
+
IdentifierStart::
+
UnicodeIDStart
+
$
+
_
+
\UnicodeEscapeSequence
+
+
+
+
IdentifierPart::
+
UnicodeIDContinue
+
$
+
_
+
\UnicodeEscapeSequence
+
<ZWNJ>
+
<ZWJ>
+
+
+
+
UnicodeIDStart::
+
any Unicode code point with the Unicode property “ID_Start”
+
+
+
+
UnicodeIDContinue::
+
any Unicode code point with the Unicode property “ID_Continue”
+
+
+
The definitions of the nonterminal UnicodeEscapeSequence is given in 11.8.4.
+
+
+
NOTE The sets of code points with Unicode properties “ID_Start” and
+ “ID_Continue” include, respectively, the code points with Unicode properties “Other_ID_Start” and
+ “Other_ID_Continue”.
It is a Syntax Error if SV(UnicodeEscapeSequence) is none
+ of "$", or "_", or the UTF16Encoding (10.1.1) of a code point that would be matched by the UnicodeIDStart lexical grammar production.
+
+
+
IdentifierPart::\UnicodeEscapeSequence
+
+
+
It is a Syntax Error if SV(UnicodeEscapeSequence) is none
+ of "$", or "_", or the UTF16Encoding (10.1.1) of either <ZWNJ> or <ZWJ>, or the UTF16Encoding of a Unicode code point that would be matched by the UnicodeIDContinue lexical grammar production.
Return the String value consisting of the sequence of code units corresponding to IdentifierName. In
+ determining the sequence any occurrences of \UnicodeEscapeSequence are first replaced with the
+ code point represented by the UnicodeEscapeSequence and then the code points of the entire
+ IdentifierName are converted to code units by UTF16Encoding (10.1.1) each code point.
A reserved word is an IdentifierName that cannot be used as an Identifier.
+
+
Syntax
+
+
+
ReservedWord::
+
Keyword
+
FutureReservedWord
+
NullLiteral
+
BooleanLiteral
+
+
+
+
NOTE The ReservedWord definitions are specified as literal sequences of specific
+ SourceCharacter elements. A code point in a ReservedWord cannot be expressed by a \
+ UnicodeEscapeSequence.
The following tokens are ECMAScript keywords and may not be used as Identifiers in ECMAScript
+ programs.
+
+
Syntax
+
Keyword::one of
+
+
+
+
+
break
+
do
+
in
+
typeof
+
+
+
case
+
else
+
instanceof
+
var
+
+
+
catch
+
export
+
new
+
void
+
+
+
class
+
extends
+
return
+
while
+
+
+
const
+
finally
+
super
+
with
+
+
+
continue
+
for
+
switch
+
yield
+
+
+
debugger
+
function
+
this
+
+
+
+
default
+
if
+
throw
+
+
+
+
delete
+
import
+
try
+
+
+
+
+
+
+
NOTE In some contexts yield is given the semantics of an Identifier. See
+ 12.1.1. In strict mode
+ code, let and static are treated as reserved keywords through static semantic restrictions
+ (see 12.1.1, 13.2.1.1, 13.6.4.1, and 14.5.1) rather than the lexical grammar.
The following tokens are reserved for used as keywords in future language extensions.
+
+
Syntax
+
FutureReservedWord::
+
+
+
+
+
enum await
+
+
+
+
+
+
+
+
await is only treated as a FutureReservedWord when Module
+ is the goal symbol of the syntactic grammar.
+
+
+
NOTE Use of the following tokens within strict mode code
+ (see 10.2.1) is also reserved. That usage is restricted using static semantic
+ restrictions (see 12.1.1) rather than the lexical
+ grammar:
The SourceCharacter immediately following a NumericLiteral must not be
+ an IdentifierStart or DecimalDigit.
+
+
+
NOTE For example:
+
+
3in
+
+
is an error and not the two input elements 3 and in.
+
+
+
A conforming implementation, when processing strict mode code (see 10.2.1), must not extend, as described in B.1.1, the syntax of NumericLiteral to include
+ LegacyOctalIntegerLiteral, nor extend the syntax of DecimalIntegerLiteral to include NonOctalDecimalIntegerLiteral.
A numeric literal stands for a value of the Number type. This value is determined in two steps: first, a mathematical
+ value (MV) is derived from the literal; second, this mathematical value is rounded as described below.
+
+
+
+
The MV of NumericLiteral::DecimalLiteral is the MV of DecimalLiteral.
+
+
+
+
The MV of NumericLiteral::BinaryIntegerLiteral is the MV of BinaryIntegerLiteral.
+
+
+
+
The MV of NumericLiteral::OctalIntegerLiteral is the MV of OctalIntegerLiteral.
+
+
+
+
The MV of NumericLiteral::HexIntegerLiteral is the MV of HexIntegerLiteral.
+
+
+
+
The MV of DecimalLiteral::DecimalIntegerLiteral. is the MV of DecimalIntegerLiteral.
+
+
+
+
The MV of DecimalLiteral::DecimalIntegerLiteral.DecimalDigits is the
+ MV of DecimalIntegerLiteral plus (the MV of DecimalDigits × 10–n), where
+ n is the number of code points in DecimalDigits.
+
+
+
+
The MV of DecimalLiteral::DecimalIntegerLiteral.ExponentPart is the MV
+ of DecimalIntegerLiteral × 10e, where e is the MV of ExponentPart.
+
+
+
+
The MV of DecimalLiteral::DecimalIntegerLiteral.DecimalDigitsExponentPart is (the MV of DecimalIntegerLiteral plus (the MV of DecimalDigits
+ × 10–n)) × 10e, where n is the number of code points in
+ DecimalDigits and e is the MV of ExponentPart.
+
+
+
+
The MV of DecimalLiteral::.DecimalDigits is the MV of DecimalDigits ×
+ 10–n, where n is the number of code points in DecimalDigits.
+
+
+
+
The MV of DecimalLiteral::.DecimalDigitsExponentPart is the MV of
+ DecimalDigits × 10e–n, where n is the number of code points in
+ DecimalDigits and e is the MV of ExponentPart.
+
+
+
+
The MV of DecimalLiteral::DecimalIntegerLiteral is the MV of DecimalIntegerLiteral.
+
+
+
+
The MV of DecimalLiteral::DecimalIntegerLiteralExponentPart is the MV of
+ DecimalIntegerLiteral × 10e, where e is the MV of ExponentPart.
+
+
+
+
The MV of DecimalIntegerLiteral::0 is 0.
+
+
+
+
The MV of DecimalIntegerLiteral::NonZeroDigit is the MV of NonZeroDigit.
+
+
+
+
The MV of DecimalIntegerLiteral::NonZeroDigitDecimalDigits is (the MV of NonZeroDigit ×
+ 10n) plus the MV of DecimalDigits, where n is the number of code points in
+ DecimalDigits.
+
+
+
+
The MV of DecimalDigits::DecimalDigit is the MV of DecimalDigit.
+
+
+
+
The MV of DecimalDigits::DecimalDigitsDecimalDigit is (the MV of DecimalDigits ×
+ 10) plus the MV of DecimalDigit.
+
+
+
+
The MV of ExponentPart::ExponentIndicatorSignedInteger is the MV of
+ SignedInteger.
+
+
+
+
The MV of SignedInteger::DecimalDigits is the MV of DecimalDigits.
+
+
+
+
The MV of SignedInteger::+DecimalDigits is the MV of DecimalDigits.
+
+
+
+
The MV of SignedInteger::-DecimalDigits is the negative of the MV of DecimalDigits.
+
+
+
+
The MV of DecimalDigit::0 or of HexDigit::0 or of OctalDigit::
+ 0 or of BinaryDigit::0 is 0.
+
+
+
+
The MV of DecimalDigit::1 or of NonZeroDigit::
+ 1 or of HexDigit::
+ 1 or of OctalDigit::1 or of BinaryDigit
+ ::1 is 1.
+
+
+
+
The MV of DecimalDigit::2 or of NonZeroDigit::
+ 2 or of HexDigit::
+ 2 or of OctalDigit::2 is 2.
+
+
+
+
The MV of DecimalDigit::3 or of NonZeroDigit::
+ 3 or of HexDigit::
+ 3 or of OctalDigit::3 is 3.
+
+
+
+
The MV of DecimalDigit::4 or of NonZeroDigit::
+ 4 or of HexDigit::
+ 4 or of OctalDigit::4 is 4.
+
+
+
+
The MV of DecimalDigit::5 or of NonZeroDigit::
+ 5 or of HexDigit::
+ 5 or of OctalDigit::5 is 5.
+
+
+
+
The MV of DecimalDigit::6 or of NonZeroDigit::
+ 6 or of HexDigit::
+ 6 or of OctalDigit::6 is 6.
+
+
+
+
The MV of DecimalDigit::7 or of NonZeroDigit::
+ 7 or of HexDigit::
+ 7 or of OctalDigit::7 is 7.
+
+
+
+
The MV of DecimalDigit::8 or of NonZeroDigit::
+ 8 or of HexDigit::
+ 8 is 8.
+
+
+
+
The MV of DecimalDigit::9 or of NonZeroDigit::
+ 9 or of HexDigit::
+ 9 is 9.
+
+
+
+
The MV of HexDigit::a or of HexDigit::A is 10.
+
+
+
+
The MV of HexDigit::b or of HexDigit::B is 11.
+
+
+
+
The MV of HexDigit::c or of HexDigit::C is 12.
+
+
+
+
The MV of HexDigit::d or of HexDigit::D is 13.
+
+
+
+
The MV of HexDigit::e or of HexDigit::E is 14.
+
+
+
+
The MV of HexDigit::f or of HexDigit::F is 15.
+
+
+
+
The MV of BinaryIntegerLiteral::0bBinaryDigits is the MV of BinaryDigits.
+
+
+
+
The MV of BinaryIntegerLiteral::0BBinaryDigits is the MV of BinaryDigits.
+
+
+
+
The MV of BinaryDigits::BinaryDigit is the MV of BinaryDigit.
+
+
+
+
The MV of BinaryDigits::BinaryDigitsBinaryDigit is (the MV of BinaryDigits × 2)
+ plus the MV of BinaryDigit.
+
+
+
+
The MV of OctalIntegerLiteral::0oOctalDigits is the MV of OctalDigits.
+
+
+
+
The MV of OctalIntegerLiteral::0OOctalDigits is the MV of OctalDigits.
+
+
+
+
The MV of OctalDigits::OctalDigit is the MV of OctalDigit.
+
+
+
+
The MV of OctalDigits::OctalDigitsOctalDigit is (the MV of OctalDigits × 8)
+ plus the MV of OctalDigit.
+
+
+
+
The MV of HexIntegerLiteral::0xHexDigits is the MV of HexDigits.
+
+
+
+
The MV of HexIntegerLiteral::0XHexDigits is the MV of HexDigits.
+
+
+
+
The MV of HexDigits::HexDigit is the MV of HexDigit.
+
+
+
+
The MV of HexDigits::HexDigitsHexDigit is (the MV of HexDigits × 16) plus
+ the MV of HexDigit.
+
+
+
+
Once the exact MV for a numeric literal has been determined, it is then rounded to a value of the Number type. If the
+ MV is 0, then the rounded value is +0; otherwise, the rounded value must be the Number value
+ for the MV (as specified in 6.1.6), unless the literal is a DecimalLiteral and the literal has more than 20 significant digits, in which case the Number value may
+ be either the Number value for the MV of a literal produced by replacing each significant digit after the 20th with a
+ 0 digit or the Number value for the MV of a literal produced by replacing each significant digit after the
+ 20th with a 0 digit and then incrementing the literal at the 20th significant digit position. A digit is
+ significant if it is not part of an ExponentPart and
+
+
+
it is not 0; or
+
there is a nonzero digit to its left and there is a nonzero digit, not in the ExponentPart, to its
+ right.
NOTE A string literal is zero or more Unicode code points enclosed in single or double
+ quotes. Unicode code points may also be represented by an escape sequence. All code points may appear literally in a string literal except for the closing quote code points, U+005C (REVERSE SOLIDUS), U+000D (carriage return), U+2028 (line
+ separator), U+2029 (paragraph separator), and U+000A (line feed). Any code
+ points may appear in the form of an escape sequence. String literals evaluate to ECMAScript String values. When
+ generating these string values Unicode code points are UTF-16 encoded as defined in 10.1.1. Code points belonging to the Basic Multilingual Plane are encoded as a single code
+ unit element of the string. All other code points are encoded as two code unit elements of the string.
+
+
+
Syntax
+
+
+
StringLiteral::
+
"DoubleStringCharactersopt"
+
'SingleStringCharactersopt'
+
+
+
+
DoubleStringCharacters::
+
DoubleStringCharacterDoubleStringCharactersopt
+
+
+
+
SingleStringCharacters::
+
SingleStringCharacterSingleStringCharactersopt
+
+
+
+
DoubleStringCharacter::
+
SourceCharacterbut not one of"or\orLineTerminator
+
\EscapeSequence
+
LineContinuation
+
+
+
+
SingleStringCharacter::
+
SourceCharacterbut not one of'or\orLineTerminator
+
\EscapeSequence
+
LineContinuation
+
+
+
+
LineContinuation::
+
\LineTerminatorSequence
+
+
+
+
EscapeSequence::
+
CharacterEscapeSequence
+
0[lookahead ∉ DecimalDigit]
+
HexEscapeSequence
+
UnicodeEscapeSequence
+
+
+
A conforming implementation, when processing strict mode code (see 10.2.1), must not extend the syntax of EscapeSequence to
+ include LegacyOctalEscapeSequence as described in B.1.2.
+
+
+
CharacterEscapeSequence::
+
SingleEscapeCharacter
+
NonEscapeCharacter
+
+
+
+
SingleEscapeCharacter::one of
+
'"\bfnrtv
+
+
+
+
NonEscapeCharacter::
+
SourceCharacterbut not one ofEscapeCharacterorLineTerminator
+
+
+
+
EscapeCharacter::
+
SingleEscapeCharacter
+
DecimalDigit
+
x
+
u
+
+
+
+
HexEscapeSequence::
+
xHexDigitHexDigit
+
+
+
+
UnicodeEscapeSequence::
+
uHex4Digits
+
u{HexDigits}
+
+
+
+
Hex4Digits::
+
HexDigitHexDigitHexDigitHexDigit
+
+
+
The definition of the nonterminal HexDigit is given in 11.8.3. SourceCharacter is defined in 10.1.
+
+
+
NOTE A line terminator code point cannot appear
+ in a string literal, except as part of a LineContinuation to produce the empty code points sequence. The proper way to cause a line terminator code point to be part of the String value of a string literal is to use an escape sequence such as
+ \n or \u000A.
A string literal stands for a value of the String type. The String value (SV) of the literal is described in terms of
+ code unit values contributed by the various parts of the string literal. As part of this process, some Unicode code points
+ within the string literal are interpreted as having a mathematical value (MV), as described below or in 11.8.3.
+
+
+
+
The SV of StringLiteral::"" is the empty code unit sequence.
+
+
+
+
The SV of StringLiteral::'' is the empty code unit sequence.
+
+
+
+
The SV of StringLiteral::"DoubleStringCharacters" is the SV of
+ DoubleStringCharacters.
+
+
+
+
The SV of StringLiteral::'SingleStringCharacters' is the SV of
+ SingleStringCharacters.
+
+
+
+
The SV of DoubleStringCharacters::DoubleStringCharacter is a sequence of one or two code units that is the SV of
+ DoubleStringCharacter.
+
+
+
+
The SV of DoubleStringCharacters::DoubleStringCharacterDoubleStringCharacters is a sequence of one or
+ two code units that is the SV of DoubleStringCharacter followed by all the code units in the SV of
+ DoubleStringCharacters in order.
+
+
+
+
The SV of SingleStringCharacters::SingleStringCharacter is a sequence of one or two code units that is the SV of
+ SingleStringCharacter.
+
+
+
+
The SV of SingleStringCharacters::SingleStringCharacterSingleStringCharacters is a sequence of one or
+ two code units that is the SV of SingleStringCharacter followed by all the code units in the SV of
+ SingleStringCharacters in order.
+
+
+
+
The SV of DoubleStringCharacter::SourceCharacterbut not one of"or\orLineTerminator is the UTF16Encoding (10.1.1) of the code point value of SourceCharacter.
+
+
+
+
The SV of DoubleStringCharacter::\EscapeSequence is the SV of the EscapeSequence.
+
+
+
+
The SV of DoubleStringCharacter::LineContinuation is the empty code unit sequence.
+
+
+
+
The SV of SingleStringCharacter::SourceCharacterbut not one of'or\orLineTerminator is the UTF16Encoding (10.1.1) of the code point value of SourceCharacter.
+
+
+
+
The SV of SingleStringCharacter::\EscapeSequence is the SV of the EscapeSequence.
+
+
+
+
The SV of SingleStringCharacter::LineContinuation is the empty code unit sequence.
+
+
+
+
The SV of EscapeSequence::CharacterEscapeSequence is the SV of the CharacterEscapeSequence.
+
+
+
+
The SV of EscapeSequence::0 is the code unit value 0.
+
+
+
+
The SV of EscapeSequence::HexEscapeSequence is the SV of the HexEscapeSequence.
+
+
+
+
The SV of EscapeSequence::UnicodeEscapeSequence is the SV of the UnicodeEscapeSequence.
+
+
+
+
The SV of CharacterEscapeSequence::SingleEscapeCharacter is the code unit whose value is determined by the
+ SingleEscapeCharacter according to { REF _Ref365803173 \h }Table 34.
+
+
+
+
+ Table 34 — String Single Character Escape Sequences
+
+
+
Escape Sequence
+
Code Unit Value
+
Unicode Character Name
+
Symbol
+
+
+
\b
+
0x0008
+
BACKSPACE
+
<BS>
+
+
+
\t
+
0x0009
+
CHARACTER TABULATION
+
<HT>
+
+
+
\n
+
0x000A
+
line feed (lf)
+
<LF>
+
+
+
\v
+
0x000B
+
LINE TABULATION
+
<VT>
+
+
+
\f
+
0x000C
+
form feed (ff)
+
<FF>
+
+
+
\r
+
0x000D
+
carriage return (cr)
+
<CR>
+
+
+
\"
+
0x0022
+
quotation Mark
+
"
+
+
+
\'
+
0x0027
+
apostrophe
+
'
+
+
+
\\
+
0x005C
+
REverse Solidus
+
\
+
+
+
+
+
+
+
The SV of CharacterEscapeSequence::NonEscapeCharacter is the SV of the NonEscapeCharacter.
+
+
+
+
The SV of NonEscapeCharacter::SourceCharacterbut not one ofEscapeCharacter
+ orLineTerminator is the UTF16Encoding (10.1.1) of the code point value of
+ SourceCharacter.
+
+
+
+
The SV of HexEscapeSequence::xHexDigitHexDigit is the code unit value
+ that is (16 times the MV of the first HexDigit) plus the MV of the second HexDigit.
+
+
+
+
The SV of UnicodeEscapeSequence::uHex4Digits is the SV of Hex4Digits.
+
+
+
+
The SV of Hex4Digits::HexDigitHexDigitHexDigitHexDigit is the code unit value that is (4096 times the MV of the first HexDigit) plus
+ (256 times the MV of the second HexDigit) plus (16 times the MV of the third HexDigit) plus the MV of
+ the fourth HexDigit.
+
+
+
+
The SV of UnicodeEscapeSequence::u{HexDigits} is the UTF16Encoding (10.1.1) of the MV of
+ HexDigits.
NOTE A regular expression literal is an input element that is converted to a RegExp object
+ (see 21.2) each time the literal is evaluated. Two regular
+ expression literals in a program evaluate to regular expression objects that never compare as === to each
+ other even if the two literals' contents are identical. A RegExp object may also be created at runtime by new
+ RegExp or calling the RegExp constructor as a function (see
+ 21.2.3).
+
+
+
The productions below describe the syntax for a regular expression literal and are used by the input element scanner to
+ find the end of the regular expression literal. The source text comprising the RegularExpressionBody and the RegularExpressionFlags are subsequently parsed
+ again using the more stringent ECMAScript Regular Expression grammar (21.2.1).
+
+
An implementation may extend the ECMAScript Regular Expression grammar defined in 21.2.1,
+ but it must not extend the RegularExpressionBody and RegularExpressionFlags productions defined below or the productions used by these productions.
+
+
Syntax
+
+
+
RegularExpressionLiteral::
+
/RegularExpressionBody/RegularExpressionFlags
+
+
+
+
RegularExpressionBody::
+
RegularExpressionFirstCharRegularExpressionChars
+
+
+
+
RegularExpressionChars::
+
[empty]
+
RegularExpressionCharsRegularExpressionChar
+
+
+
+
RegularExpressionFirstChar::
+
RegularExpressionNonTerminatorbut not one of*or\or/or[
+
RegularExpressionBackslashSequence
+
RegularExpressionClass
+
+
+
+
RegularExpressionChar::
+
RegularExpressionNonTerminatorbut not one of\or/or[
NOTE Regular expression literals may not be empty; instead of representing an empty regular
+ expression literal, the code unit sequence // starts a single-line comment. To specify an empty regular
+ expression, use: /(?:)/.
A template literal component is interpreted as a sequence of Unicode code points. The Template Value (TV) of a literal
+ component is described in terms of code unit values (SV, 11.8.4) contributed
+ by the various parts of the template literal component. As part of this process, some Unicode code points within the
+ template component are interpreted as having a mathematical value (MV, 11.8.3). In determining a TV, escape sequences are replaced by the UTF-16 code
+ unit(s) of the Unicode code point represented by the escape sequence. The Template Raw Value (TRV) is similar to a
+ Template Value with the difference that in TRVs escape sequences are interpreted literally.
+
+
+
+
The TV and TRV of NoSubstitutionTemplate::
+ `` is the empty code unit sequence.
+
+
+
+
The TV and TRV of TemplateHead::`${ is the empty code unit sequence.
+
+
+
+
The TV and TRV of TemplateMiddle::}${ is the empty code unit sequence.
+
+
+
+
The TV and TRV of TemplateTail::}` is the empty code unit sequence.
+
+
+
+
The TV of NoSubstitutionTemplate::`TemplateCharacters` is the TV of
+ TemplateCharacters.
+
+
+
+
The TV of TemplateHead::`TemplateCharacters${ is the TV of
+ TemplateCharacters.
+
+
+
+
The TV of TemplateMiddle::}TemplateCharacters${ is the TV of
+ TemplateCharacters.
+
+
+
+
The TV of TemplateTail::}TemplateCharacters` is the TV of
+ TemplateCharacters.
+
+
+
+
The TV of TemplateCharacters::TemplateCharacter is the TV of TemplateCharacter.
+
+
+
+
The TV of TemplateCharacters::TemplateCharacterTemplateCharacters is a sequence consisting of the
+ code units in the TV of TemplateCharacter followed by all the code units in the TV of TemplateCharacters
+ in order.
+
+
+
+
The TV of TemplateCharacter::SourceCharacterbut not one of`or\or$orLineTerminator is the UTF16Encoding (10.1.1) of the code point value of
+ SourceCharacter.
+
+
+
+
The TV of TemplateCharacter::$ is the code unit value 0x0024.
+
+
+
+
The TV of TemplateCharacter::\EscapeSequence is the SV of EscapeSequence.
+
+
+
+
The TV of TemplateCharacter::LineContinuation is the TV of LineContinuation.
+
+
+
+
The TV of TemplateCharacter::LineTerminatorSequence is the TRV of LineTerminatorSequence.
+
+
+
+
The TV of LineContinuation::\LineTerminatorSequence is the empty code unit sequence.
+
+
+
+
The TRV of NoSubstitutionTemplate::`TemplateCharacters` is the TRV of
+ TemplateCharacters.
+
+
+
+
The TRV of TemplateHead::`TemplateCharacters${ is the TRV of
+ TemplateCharacters.
+
+
+
+
The TRV of TemplateMiddle::}TemplateCharacters${ is the TRV of
+ TemplateCharacters.
+
+
+
+
The TRV of TemplateTail::}TemplateCharacters` is the TRV of
+ TemplateCharacters.
+
+
+
+
The TRV of TemplateCharacters::TemplateCharacter is the TRV of TemplateCharacter.
+
+
+
+
The TRV of TemplateCharacters::TemplateCharacterTemplateCharacters is a sequence consisting of the
+ code units in the TRV of TemplateCharacter followed by all the code units in the TRV of
+ TemplateCharacters, in order.
+
+
+
+
The TRV of TemplateCharacter::SourceCharacterbut not one of`or\or$orLineTerminator is the UTF16Encoding (10.1.1) of the code point value of
+ SourceCharacter.
+
+
+
+
The TRV of TemplateCharacter::$ is the code unit value 0x0024.
+
+
+
+
The TRV of TemplateCharacter::\EscapeSequence is the sequence consisting of the code unit value
+ 0x005C followed by the code units of TRV of EscapeSequence.
+
+
+
+
The TRV of TemplateCharacter::LineContinuation is the TRV of LineContinuation.
+
+
+
+
The TRV of TemplateCharacter::LineTerminatorSequence is the TRV of LineTerminatorSequence.
+
+
+
+
The TRV of EscapeSequence::CharacterEscapeSequence is the TRV of the CharacterEscapeSequence.
+
+
+
+
The TRV of EscapeSequence::0 is the code unit value 0x0030.
+
+
+
+
The TRV of EscapeSequence::HexEscapeSequence is the TRV of the HexEscapeSequence.
+
+
+
+
The TRV of EscapeSequence::UnicodeEscapeSequence is the TRV of the UnicodeEscapeSequence.
+
+
+
+
The TRV of CharacterEscapeSequence::SingleEscapeCharacter is the TRV of the SingleEscapeCharacter.
+
+
+
+
The TRV of CharacterEscapeSequence::NonEscapeCharacter is the SV of the NonEscapeCharacter.
+
+
+
+
The TRV of SingleEscapeCharacter::one of'"\bfnrt
+ v is the SV of the SourceCharacter that is that single code point.
+
+
+
+
The TRV of HexEscapeSequence::xHexDigitHexDigit is the sequence
+ consisting of code unit value 0x0078 followed by TRV of the first HexDigit followed by the TRV of the second
+ HexDigit.
+
+
+
+
The TRV of UnicodeEscapeSequence::uHex4Digits is the sequence consisting of code unit value 0x0075
+ followed by TRV of Hex4Digits.
+
+
+
+
The TRV of UnicodeEscapeSequence::u{HexDigits} is the sequence consisting of
+ code unit value 0x0075 followed by code unit value 0x007B followed by TRV of HexDigits followed by code unit
+ value 0x007D.
+
+
+
+
The TRV of Hex4Digits::HexDigitHexDigitHexDigitHexDigit is the sequence consisting of the TRV of the first HexDigit followed by the
+ TRV of the second HexDigit followed by the TRV of the third HexDigit followed by the TRV of the fourth
+ HexDigit.
+
+
+
+
The TRV of HexDigits::HexDigit is the TRV of HexDigit.
+
+
+
+
The TRV of HexDigits::HexDigitsHexDigit is the sequence consisting of TRV of
+ HexDigits followed by TRV of HexDigit.
+
+
+
+
The TRV of a HexDigit is the SV of the SourceCharacter that is that HexDigit.
+
+
+
+
The TRV of LineContinuation::\LineTerminatorSequence is the sequence consisting of the code unit
+ value 0x005C followed by the code units of TRV of LineTerminatorSequence.
+
+
+
+
The TRV of LineTerminatorSequence::
+ <LF> is the code unit value 0x000A.
+
+
+
+
The TRV of LineTerminatorSequence::
+ <CR> is the code unit value 0x000A.
+
+
+
+
The TRV of LineTerminatorSequence::
+ <LS> is the code unit value 0x2028.
+
+
+
+
The TRV of LineTerminatorSequence::
+ <PS> is the code unit value 0x2029.
+
+
+
+
The TRV of LineTerminatorSequence::
+ <CR><LF> is the sequence consisting of the code unit value 0x000A.
+
+
+
+
+
NOTE TV excludes the code units of LineContinuation while TRV includes them.
+ <CR><LF> and <CR> LineTerminatorSequences are normalized to <LF> for both TV and TRV. An
+ explicit EscapeSequence is needed to include a <CR> or <CR><LF> sequence.
Certain ECMAScript statements (empty statement, let, const, import, and
+ export declarations, variable statement, expression statement, debugger statement,
+ continue statement, break statement, return statement, and throw
+ statement) must be terminated with semicolons. Such semicolons may always appear explicitly in the source text. For
+ convenience, however, such semicolons may be omitted from the source text in certain situations. These situations are
+ described by saying that semicolons are automatically inserted into the source code token stream in those situations.
In the following rules, “token” means the actual recognized lexical token determined using the current
+ lexical goal symbol as described in clause 11.
+
+
There are three basic rules of semicolon insertion:
+
+
+
When, as a Script or Module is parsed from left to
+ right, a token (called the offending token) is encountered that is not allowed by any production of the
+ grammar, then a semicolon is automatically inserted before the offending token if one or more of the following
+ conditions is true:
+
+
+
The offending token is separated from the previous token by at least one LineTerminator.
+
+
+
+
The offending token is }.
+
+
+
+
The previous token is ) and the inserted semicolon would then be parsed as the terminating semicolon
+ of a do-while statement (13.6.1).
+
+
+
+
When, as the Script or Module is parsed from left to
+ right, the end of the input stream of tokens is encountered and the parser is unable to parse the input token stream
+ as a single complete ECMAScript Script or Module, then
+ a semicolon is automatically inserted at the end of the input stream.
+
When, as the Script or Module is parsed from left to
+ right, a token is encountered that is allowed by some production of the grammar, but the production is a restricted
+ production and the token would be the first token for a terminal or nonterminal immediately following the
+ annotation “[no LineTerminator here]” within the restricted production (and therefore such a token is
+ called a restricted token), and the restricted token is separated from the previous token by at least one LineTerminator, then a semicolon is automatically inserted before the restricted token.
+
+
+
However, there is an additional overriding condition on the preceding rules: a semicolon is never inserted automatically
+ if the semicolon would then be parsed as an empty statement or if that semicolon would become one of the two semicolons in
+ the header of a for statement (see 13.6.3).
+
+
+
NOTE The following are the only restricted productions in the grammar:
The practical effect of these restricted productions is as follows:
+
+
When a ++ or -- token is encountered where the parser would treat it as a postfix operator, and
+ at least one LineTerminator occurred between the preceding token and the ++ or
+ -- token, then a semicolon is automatically inserted before the ++ or -- token.
+
+
When a continue, break, return, throw, or yield token is
+ encountered and a LineTerminator is encountered before the next token, a semicolon is automatically
+ inserted after the continue, break, return, throw, or yield
+ token.
+
+
The resulting practical advice to ECMAScript programmers is:
+
+
A postfix ++ or -- operator should appear on the same line as its operand.
+
+
An Expression in a return or throw statement or an AssignmentExpression in a yield expression should start on the same line as the
+ return, throw, or yield token.
+
+
An IdentifierReference in a break or continue statement should be on
+ the same line as the break or continue token.
is not a valid ECMAScript sentence and is not altered by automatic semicolon
+ insertion because the semicolon is needed for the header of a for statement. Automatic semicolon insertion
+ never inserts one of the two semicolons in the header of a for statement.
NOTE The expression a + b is not treated as a value to be returned by the
+ return statement, because a LineTerminator separates it from the token return.
NOTE The token ++ is not treated as a postfix operator applying to the variable
+ b, because a LineTerminator occurs between b and ++.
+
+
+
The source
+
+
if (a > b) else c = d
+
+
is not a valid ECMAScript sentence and is not altered by automatic semicolon
+ insertion before the else token, even though no production of the grammar applies at that point, because an
+ automatically inserted semicolon would then be parsed as an empty statement.
+
+
The source
+
+
a = b + c (d + e).print()
+
+
is not transformed by automatic semicolon insertion, because the
+ parenthesized expression that begins the second line can be interpreted as an argument list for a function call:
+
+
a = b + c(d + e).print()
+
+
In the circumstance that an assignment statement must begin with a left parenthesis, it is a good idea for the programmer
+ to provide an explicit semicolon at the end of the preceding statement rather than to rely on automatic semicolon insertion.
It is a Syntax Error if the code matched by this production is contained in strict
+ mode code and the StringValue of Identifier is "arguments" or
+ "eval".
+
+
+
+
IdentifierReference:yield
+
+
BindingIdentifier:yield
+
+
LabelIdentifier:yield
+
+
+
It is a Syntax Error if the code matched by this production is contained in strict
+ code.
+
+
+
+
IdentifierReference[Yield]:Identifier
+
+
BindingIdentifier[Yield]:Identifier
+
+
LabelIdentifier[Yield]:Identifier
+
+
+
+
It is a Syntax Error if this production has a [Yield] parameter and StringValue of Identifier is "yield".
+
+
+
Identifier:IdentifierNamebut notReservedWord
+
+
+
It is a Syntax Error if this phrase is contained in strict mode code and the
+ StringValue of IdentifierName is: "implements", "interface",
+ "let", "package", "private", "protected", "public",
+ "static", or "yield".
+
+
+
+
It is a Syntax Error if StringValue of IdentifierName is the same string value as the
+ StringValue of any ReservedWord except for yield.
+
+
+
+
+
NOTEStringValue ofIdentifierName
+ normalizes any Unicode escape sequences in IdentifierName hence such escapes cannot be used to write an
+ Identifier whose code point sequence is the same as a ReservedWord.
NOTEundefined is passed for environment to indicate that a PutValue operation should be used to assign the initialization value. This is the case for
+ var statements and formal parameter lists of some non-strict functions (See 9.2.12). In those cases a lexical binding is hoisted and preinitialized
+ prior to evaluation of its initializer.
NOTE 1: The result of evaluating an IdentifierReference is always a value of type Reference.
+
+
+
+
NOTE 2: In non-strict code, the keyword yield
+ may be used as an identifier. Evaluating the IdentifierReference production resolves the binding of
+ yield as if it was an Identifier. Early Error restriction ensures that such an evaluation only can
+ occur for non-strict code. See 13.2.1
+ for the handling of yield in binding creation contexts.
PrimaryExpression[Yield]:CoverParenthesizedExpressionAndArrowParameterList[?Yield] the interpretation of CoverParenthesizedExpressionAndArrowParameterList is
+ refined using the following grammar:
Return the result of parsing the lexical token stream matched by
+ CoverParenthesizedExpressionAndArrowParameterList[Yield] using either
+ ParenthesizedExpression or ParenthesizedExpression[Yield] as the goal symbol depending upon
+ whether the [Yield] grammar parameter was present when
+ CoverParenthesizedExpressionAndArrowParameterList was matched.
NOTE An ArrayLiteral is an expression describing the initialization of an Array
+ object, using a list, of zero or more expressions each of which represents an array element, enclosed in square
+ brackets. The elements need not be literals; they are evaluated each time the array initializer is evaluated.
+
+
+
Array elements may be elided at the beginning, middle or end of the element list. Whenever a comma in the element list
+ is not preceded by an AssignmentExpression (i.e., a comma at the beginning or after another
+ comma), the missing array element contributes to the length of the Array and increases the index of subsequent elements.
+ Elided array elements are not defined. If an element is elided at the end of an array, that element does not contribute to
+ the length of the Array.
NOTECreateDataProperty is used to ensure that own
+ properties are defined for the array even if the standard built-in Array prototype object has been modified in a manner
+ that would preclude the creation of new own properties using [[Set]].
NOTE 1 An object initializer is an expression describing the initialization of an Object,
+ written in a form resembling a literal. It is a list of zero or more pairs of property keys and associated values,
+ enclosed in curly brackets. The values need not be literals; they are evaluated each time the object initializer is
+ evaluated.
NOTE 3 In certain contexts, ObjectLiteral is used as a cover grammar for a more
+ restricted secondary grammar. The CoverInitializedName production is necessary to fully cover these secondary
+ grammars. However, use of this production results in an early Syntax Error in normal contexts where an actual
+ ObjectLiteral is expected.
It is a Syntax Error if HasDirectSuper of MethodDefinition is true.
+
+
+
In addition to describing an actual object initializer the ObjectLiteral productions are also
+ used as a cover grammar for ObjectAssignmentPattern (12.14.5). and may be recognized as part of a CoverParenthesizedExpressionAndArrowParameterList. When ObjectLiteral appears in
+ a context where ObjectAssignmentPattern is required the following Early Error rules are not
+ applied. In addition, they are not applied when initially parsing a
+ CoverParenthesizedExpressionAndArrowParameterList.
+
+
PropertyDefinition:CoverInitializedName
+
+
Always throw a Syntax Error if code matches this production.
+
+
+
+
NOTE This production exists so that ObjectLiteral can serve as a cover grammar for
+ ObjectAssignmentPattern (12.14.5). It cannot occur in an actual
+ object initializer.
It is a Syntax Error if BodyText of RegularExpressionLiteral cannot be recognized using the goal symbol Pattern
+ of the ECMAScript RegExp grammar specified in 21.2.1.
+
+
+
+
It is a Syntax Error if FlagText of RegularExpressionLiteral contains any code points other than "g", "i",
+ "m", "u", or "y", or if it contains the same code point more than once.
Return a List whose first element is siteObj, whose
+ second elements is firstSub, and whose subsequent elements are the elements of restSub, in order.
+ restSub may contain no elements.
Append the Record{[[strings]]: rawStrings, [[array]]: template} to templateRegistry.
+
Return template.
+
+
+
+
NOTE 1 The creation of a template object cannot result in an abrupt completion.
+
+
+
+
NOTE 2 Each TemplateLiteral in the program code of a Realm is associated with a unique template object that is used in the evaluation of tagged
+ Templates (12.2.8.5). The template objects are frozen
+ and the same template object is used each time a specific tagged Template is evaluated. Whether template objects are
+ created lazily upon first evaluation of the TemplateLiteral or eagerly prior to first evaluation is an
+ implementation choice that is not observable to ECMAScript code.
+
+
+
+
NOTE 3 Future editions of this specification may define additional non-enumerable properties
+ of template objects.
It is a Syntax Error if the lexical token sequence matched by CoverParenthesizedExpressionAndArrowParameterList cannot be parsed with no tokens left over using
+ ParenthesizedExpression as the goal symbol.
+
+
+
+
All Early Errors rules for ParenthesizedExpression and its derived productions also apply
+ to CoveredParenthesizedExpression of CoverParenthesizedExpressionAndArrowParameterList.
Let expr be CoveredParenthesizedExpression of CoverParenthesizedExpressionAndArrowParameterList.
+
Return the result of evaluating expr.
+
+
ParenthesizedExpression:(Expression)
+
+
Return the result of evaluating Expression. This may be of type Reference.
+
+
+
+
NOTE This algorithm does not apply GetValue to the result of
+ evaluating Expression. The principal motivation for this is so that operators such as delete and
+ typeof may be applied to parenthesized expressions.
Let propertyNameString be StringValue of IdentifierName
+
If the code matched by the syntactic production that is being evaluated is strict
+ mode code, let strict be true, else let strict be false.
+
Return a value of type Reference whose base value is bv and
+ whose referenced name is propertyNameString, and whose strict reference flag is strict.
+
+
CallExpression:CallExpression[Expression]
+
+
Is evaluated in exactly the same manner as MemberExpression:MemberExpression[Expression
+ ] except that the contained CallExpression is evaluated in step
+ 1.
+
+
CallExpression:CallExpression.IdentifierName
+
+
Is evaluated in exactly the same manner as MemberExpression:MemberExpression.IdentifierName except that the contained CallExpression is evaluated in
+ step 1.
The abstract operation EvaluateCall takes as arguments a value ref, a syntactic grammar production
+ arguments, and a Boolean argument tailPosition. It performs the following steps:
The abstract operation EvaluateDirectCall takes as arguments a value func, a value thisValue, a
+ syntactic grammar production arguments, and a Boolean argument tailPosition. It performs the
+ following steps:
Assert: If tailPosition is true, the above call will not
+ return here, but instead evaluation will continue as if the following return has already occurred.
Return a value of type Reference that is a Super Reference whose base value is bv, whose referenced name is
+ propertyKey, whose thisValue is actualThis, and whose strict reference flag is strict.
NOTE A tagged template is a function call where the arguments of the call are derived from a
+ TemplateLiteral (12.2.8). The actual arguments include a template object (12.2.8.3) and the values produced by evaluating the expressions embedded within the
+ TemplateLiteral.
It is a Syntax Error if the UnaryExpression is contained in strict mode code and the derived UnaryExpression is PrimaryExpression:
+ IdentifierReference.
+
+
+
+
It is a Syntax Error if the derived UnaryExpression is PrimaryExpression : CoverParenthesizedExpressionAndArrowParameterList and CoverParenthesizedExpressionAndArrowParameterList ultimately derives a phrase that, if used in place
+ of UnaryExpression, would produce a Syntax Error according to these rules. This rule is recursively
+ applied.
+
+
+
+
+
NOTE The last rule means that expressions such as delete
+ (((foo))) produce early errors because of recursive application of the first rule.
NOTE When a delete operator occurs within strict
+ mode code, a SyntaxError exception is thrown if its UnaryExpression is a direct reference to a
+ variable, function argument, or function name. In addition, if a delete operator occurs within strict mode code and the property to be deleted has the attribute { [[Configurable]]:
+ false }, a TypeError exception is thrown.
Object (standard exotic and does not implement [[Call]])
+
"object"
+
+
+
Object (implements [[Call]])
+
"function"
+
+
+
Object (non-standard exotic and does not implement [[Call]])
+
Implementation-defined. Must not be "undefined", "boolean", "function", "number", "symbol", or "string".
+
+
+
+
+
+
NOTE Implementations are discouraged from defining new typeof result values for
+ non-standard exotic objects. If possible "object"should be used for such objects.
The *MultiplicativeOperator performs multiplication, producing the product of its
+ operands. Multiplication is commutative. Multiplication is not always associative in ECMAScript, because of finite
+ precision.
+
+
The result of a floating-point multiplication is governed by the rules of IEEE 754 binary double-precision
+ arithmetic:
+
+
+
+
If either operand is NaN, the result is NaN.
+
+
+
+
The sign of the result is positive if both operands have the same sign, negative if the operands have different
+ signs.
+
+
+
+
Multiplication of an infinity by a zero results in NaN.
+
+
+
+
Multiplication of an infinity by an infinity results in an infinity. The sign is determined by the rule already
+ stated above.
+
+
+
+
Multiplication of an infinity by a finite nonzero value results in a signed infinity. The sign is determined by the
+ rule already stated above.
+
+
+
+
In the remaining cases, where neither an infinity nor NaN is involved, the product is computed and rounded to the
+ nearest representable value using IEEE 754 round-to-nearest mode. If the magnitude is too large to represent, the
+ result is then an infinity of appropriate sign. If the magnitude is too small to represent, the result is then a zero
+ of appropriate sign. The ECMAScript language requires support of gradual underflow as defined by IEEE 754.
The /MultiplicativeOperator performs division, producing the quotient of its
+ operands. The left operand is the dividend and the right operand is the divisor. ECMAScript does not perform integer
+ division. The operands and result of all division operations are double-precision floating-point numbers. The result of
+ division is determined by the specification of IEEE 754 arithmetic:
+
+
+
+
If either operand is NaN, the result is NaN.
+
+
+
+
The sign of the result is positive if both operands have the same sign, negative if the operands have different
+ signs.
+
+
+
+
Division of an infinity by an infinity results in NaN.
+
+
+
+
Division of an infinity by a zero results in an infinity. The sign is determined by the rule already stated
+ above.
+
+
+
+
Division of an infinity by a nonzero finite value results in a signed infinity. The sign is determined by the rule
+ already stated above.
+
+
+
+
Division of a finite value by an infinity results in zero. The sign is determined by the rule already stated
+ above.
+
+
+
+
Division of a zero by a zero results in NaN; division of zero by any other finite value results in zero,
+ with the sign determined by the rule already stated above.
+
+
+
+
Division of a nonzero finite value by a zero results in a signed infinity. The sign is determined by the rule
+ already stated above.
+
+
+
+
In the remaining cases, where neither an infinity, nor a zero, nor NaN is involved, the quotient is computed
+ and rounded to the nearest representable value using IEEE 754 round-to-nearest mode. If the magnitude is too large to
+ represent, the operation overflows; the result is then an infinity of appropriate sign. If the magnitude is too small
+ to represent, the operation underflows and the result is a zero of the appropriate sign. The ECMAScript language
+ requires support of gradual underflow as defined by IEEE 754.
The %MultiplicativeOperator yields the remainder of its operands from an implied
+ division; the left operand is the dividend and the right operand is the divisor.
+
+
+
NOTE In C and C++, the remainder operator accepts only integral operands; in ECMAScript, it
+ also accepts floating-point operands.
+
+
+
The result of a floating-point remainder operation as computed by the % operator is not the same as the
+ “remainder” operation defined by IEEE 754. The IEEE 754 “remainder” operation computes the
+ remainder from a rounding division, not a truncating division, and so its behaviour is not analogous to that of the usual
+ integer remainder operator. Instead the ECMAScript language defines % on floating-point operations to behave
+ in a manner analogous to that of the Java integer remainder operator; this may be compared with the C library function
+ fmod.
+
+
The result of an ECMAScript floating-point remainder operation is determined by the rules of IEEE arithmetic:
+
+
+
+
If either operand is NaN, the result is NaN.
+
+
+
+
The sign of the result equals the sign of the dividend.
+
+
+
+
If the dividend is an infinity, or the divisor is a zero, or both, the result is NaN.
+
+
+
+
If the dividend is finite and the divisor is an infinity, the result equals the dividend.
+
+
+
+
If the dividend is a zero and the divisor is nonzero and finite, the result is the same as the dividend.
+
+
+
+
In the remaining cases, where neither an infinity, nor a zero, nor NaN is involved, the floating-point
+ remainder r from a dividend n and a divisor d is defined by the mathematical relation r = n − (d × q)
+ where q is an integer that is negative only if n/d is negative and positive only if n/d is positive, and whose
+ magnitude is as large as possible without exceeding the magnitude of the true mathematical quotient of n and d. r is
+ computed and rounded to the nearest representable value using IEEE 754 round-to-nearest mode.