532 lines
12 KiB
Go
532 lines
12 KiB
Go
// Copyright 2017 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package message
|
|
|
|
import (
|
|
"bytes"
|
|
"strconv"
|
|
"unicode/utf8"
|
|
)
|
|
|
|
const (
|
|
ldigits = "0123456789abcdefx"
|
|
udigits = "0123456789ABCDEFX"
|
|
)
|
|
|
|
const (
|
|
signed = true
|
|
unsigned = false
|
|
)
|
|
|
|
// flags placed in a separate struct for easy clearing.
|
|
type fmtFlags struct {
|
|
widPresent bool
|
|
precPresent bool
|
|
minus bool
|
|
plus bool
|
|
sharp bool
|
|
space bool
|
|
zero bool
|
|
|
|
// For the formats %+v %#v, we set the plusV/sharpV flags
|
|
// and clear the plus/sharp flags since %+v and %#v are in effect
|
|
// different, flagless formats set at the top level.
|
|
plusV bool
|
|
sharpV bool
|
|
}
|
|
|
|
// A formatInfo is the raw formatter used by Printf etc.
|
|
// It prints into a buffer that must be set up separately.
|
|
type formatInfo struct {
|
|
buf *bytes.Buffer
|
|
|
|
fmtFlags
|
|
|
|
wid int // width
|
|
prec int // precision
|
|
|
|
// intbuf is large enough to store %b of an int64 with a sign and
|
|
// avoids padding at the end of the struct on 32 bit architectures.
|
|
intbuf [68]byte
|
|
}
|
|
|
|
func (f *formatInfo) clearflags() {
|
|
f.fmtFlags = fmtFlags{}
|
|
}
|
|
|
|
func (f *formatInfo) init(buf *bytes.Buffer) {
|
|
f.buf = buf
|
|
f.clearflags()
|
|
}
|
|
|
|
// writePadding generates n bytes of padding.
|
|
func (f *formatInfo) writePadding(n int) {
|
|
if n <= 0 { // No padding bytes needed.
|
|
return
|
|
}
|
|
f.buf.Grow(n)
|
|
// Decide which byte the padding should be filled with.
|
|
padByte := byte(' ')
|
|
if f.zero {
|
|
padByte = byte('0')
|
|
}
|
|
// Fill padding with padByte.
|
|
for i := 0; i < n; i++ {
|
|
f.buf.WriteByte(padByte) // TODO: make more efficient.
|
|
}
|
|
}
|
|
|
|
// pad appends b to f.buf, padded on left (!f.minus) or right (f.minus).
|
|
func (f *formatInfo) pad(b []byte) {
|
|
if !f.widPresent || f.wid == 0 {
|
|
f.buf.Write(b)
|
|
return
|
|
}
|
|
width := f.wid - utf8.RuneCount(b)
|
|
if !f.minus {
|
|
// left padding
|
|
f.writePadding(width)
|
|
f.buf.Write(b)
|
|
} else {
|
|
// right padding
|
|
f.buf.Write(b)
|
|
f.writePadding(width)
|
|
}
|
|
}
|
|
|
|
// padString appends s to f.buf, padded on left (!f.minus) or right (f.minus).
|
|
func (f *formatInfo) padString(s string) {
|
|
if !f.widPresent || f.wid == 0 {
|
|
f.buf.WriteString(s)
|
|
return
|
|
}
|
|
width := f.wid - utf8.RuneCountInString(s)
|
|
if !f.minus {
|
|
// left padding
|
|
f.writePadding(width)
|
|
f.buf.WriteString(s)
|
|
} else {
|
|
// right padding
|
|
f.buf.WriteString(s)
|
|
f.writePadding(width)
|
|
}
|
|
}
|
|
|
|
// fmt_boolean formats a boolean.
|
|
func (f *formatInfo) fmt_boolean(v bool) {
|
|
if v {
|
|
f.padString("true")
|
|
} else {
|
|
f.padString("false")
|
|
}
|
|
}
|
|
|
|
// fmt_unicode formats a uint64 as "U+0078" or with f.sharp set as "U+0078 'x'".
|
|
func (f *formatInfo) fmt_unicode(u uint64) {
|
|
buf := f.intbuf[0:]
|
|
|
|
// With default precision set the maximum needed buf length is 18
|
|
// for formatting -1 with %#U ("U+FFFFFFFFFFFFFFFF") which fits
|
|
// into the already allocated intbuf with a capacity of 68 bytes.
|
|
prec := 4
|
|
if f.precPresent && f.prec > 4 {
|
|
prec = f.prec
|
|
// Compute space needed for "U+" , number, " '", character, "'".
|
|
width := 2 + prec + 2 + utf8.UTFMax + 1
|
|
if width > len(buf) {
|
|
buf = make([]byte, width)
|
|
}
|
|
}
|
|
|
|
// Format into buf, ending at buf[i]. Formatting numbers is easier right-to-left.
|
|
i := len(buf)
|
|
|
|
// For %#U we want to add a space and a quoted character at the end of the buffer.
|
|
if f.sharp && u <= utf8.MaxRune && strconv.IsPrint(rune(u)) {
|
|
i--
|
|
buf[i] = '\''
|
|
i -= utf8.RuneLen(rune(u))
|
|
utf8.EncodeRune(buf[i:], rune(u))
|
|
i--
|
|
buf[i] = '\''
|
|
i--
|
|
buf[i] = ' '
|
|
}
|
|
// Format the Unicode code point u as a hexadecimal number.
|
|
for u >= 16 {
|
|
i--
|
|
buf[i] = udigits[u&0xF]
|
|
prec--
|
|
u >>= 4
|
|
}
|
|
i--
|
|
buf[i] = udigits[u]
|
|
prec--
|
|
// Add zeros in front of the number until requested precision is reached.
|
|
for prec > 0 {
|
|
i--
|
|
buf[i] = '0'
|
|
prec--
|
|
}
|
|
// Add a leading "U+".
|
|
i--
|
|
buf[i] = '+'
|
|
i--
|
|
buf[i] = 'U'
|
|
|
|
oldZero := f.zero
|
|
f.zero = false
|
|
f.pad(buf[i:])
|
|
f.zero = oldZero
|
|
}
|
|
|
|
// fmt_integer formats signed and unsigned integers.
|
|
func (f *formatInfo) fmt_integer(u uint64, base int, isSigned bool, digits string) {
|
|
negative := isSigned && int64(u) < 0
|
|
if negative {
|
|
u = -u
|
|
}
|
|
|
|
buf := f.intbuf[0:]
|
|
// The already allocated f.intbuf with a capacity of 68 bytes
|
|
// is large enough for integer formatting when no precision or width is set.
|
|
if f.widPresent || f.precPresent {
|
|
// Account 3 extra bytes for possible addition of a sign and "0x".
|
|
width := 3 + f.wid + f.prec // wid and prec are always positive.
|
|
if width > len(buf) {
|
|
// We're going to need a bigger boat.
|
|
buf = make([]byte, width)
|
|
}
|
|
}
|
|
|
|
// Two ways to ask for extra leading zero digits: %.3d or %03d.
|
|
// If both are specified the f.zero flag is ignored and
|
|
// padding with spaces is used instead.
|
|
prec := 0
|
|
if f.precPresent {
|
|
prec = f.prec
|
|
// Precision of 0 and value of 0 means "print nothing" but padding.
|
|
if prec == 0 && u == 0 {
|
|
oldZero := f.zero
|
|
f.zero = false
|
|
f.writePadding(f.wid)
|
|
f.zero = oldZero
|
|
return
|
|
}
|
|
} else if f.zero && f.widPresent {
|
|
prec = f.wid
|
|
if negative || f.plus || f.space {
|
|
prec-- // leave room for sign
|
|
}
|
|
}
|
|
|
|
// Because printing is easier right-to-left: format u into buf, ending at buf[i].
|
|
// We could make things marginally faster by splitting the 32-bit case out
|
|
// into a separate block but it's not worth the duplication, so u has 64 bits.
|
|
i := len(buf)
|
|
// Use constants for the division and modulo for more efficient code.
|
|
// Switch cases ordered by popularity.
|
|
switch base {
|
|
case 10:
|
|
for u >= 10 {
|
|
i--
|
|
next := u / 10
|
|
buf[i] = byte('0' + u - next*10)
|
|
u = next
|
|
}
|
|
case 16:
|
|
for u >= 16 {
|
|
i--
|
|
buf[i] = digits[u&0xF]
|
|
u >>= 4
|
|
}
|
|
case 8:
|
|
for u >= 8 {
|
|
i--
|
|
buf[i] = byte('0' + u&7)
|
|
u >>= 3
|
|
}
|
|
case 2:
|
|
for u >= 2 {
|
|
i--
|
|
buf[i] = byte('0' + u&1)
|
|
u >>= 1
|
|
}
|
|
default:
|
|
panic("fmt: unknown base; can't happen")
|
|
}
|
|
i--
|
|
buf[i] = digits[u]
|
|
for i > 0 && prec > len(buf)-i {
|
|
i--
|
|
buf[i] = '0'
|
|
}
|
|
|
|
// Various prefixes: 0x, -, etc.
|
|
if f.sharp {
|
|
switch base {
|
|
case 8:
|
|
if buf[i] != '0' {
|
|
i--
|
|
buf[i] = '0'
|
|
}
|
|
case 16:
|
|
// Add a leading 0x or 0X.
|
|
i--
|
|
buf[i] = digits[16]
|
|
i--
|
|
buf[i] = '0'
|
|
}
|
|
}
|
|
|
|
if negative {
|
|
i--
|
|
buf[i] = '-'
|
|
} else if f.plus {
|
|
i--
|
|
buf[i] = '+'
|
|
} else if f.space {
|
|
i--
|
|
buf[i] = ' '
|
|
}
|
|
|
|
// Left padding with zeros has already been handled like precision earlier
|
|
// or the f.zero flag is ignored due to an explicitly set precision.
|
|
oldZero := f.zero
|
|
f.zero = false
|
|
f.pad(buf[i:])
|
|
f.zero = oldZero
|
|
}
|
|
|
|
// truncate truncates the string to the specified precision, if present.
|
|
func (f *formatInfo) truncate(s string) string {
|
|
if f.precPresent {
|
|
n := f.prec
|
|
for i := range s {
|
|
n--
|
|
if n < 0 {
|
|
return s[:i]
|
|
}
|
|
}
|
|
}
|
|
return s
|
|
}
|
|
|
|
// fmt_s formats a string.
|
|
func (f *formatInfo) fmt_s(s string) {
|
|
s = f.truncate(s)
|
|
f.padString(s)
|
|
}
|
|
|
|
// fmt_sbx formats a string or byte slice as a hexadecimal encoding of its bytes.
|
|
func (f *formatInfo) fmt_sbx(s string, b []byte, digits string) {
|
|
length := len(b)
|
|
if b == nil {
|
|
// No byte slice present. Assume string s should be encoded.
|
|
length = len(s)
|
|
}
|
|
// Set length to not process more bytes than the precision demands.
|
|
if f.precPresent && f.prec < length {
|
|
length = f.prec
|
|
}
|
|
// Compute width of the encoding taking into account the f.sharp and f.space flag.
|
|
width := 2 * length
|
|
if width > 0 {
|
|
if f.space {
|
|
// Each element encoded by two hexadecimals will get a leading 0x or 0X.
|
|
if f.sharp {
|
|
width *= 2
|
|
}
|
|
// Elements will be separated by a space.
|
|
width += length - 1
|
|
} else if f.sharp {
|
|
// Only a leading 0x or 0X will be added for the whole string.
|
|
width += 2
|
|
}
|
|
} else { // The byte slice or string that should be encoded is empty.
|
|
if f.widPresent {
|
|
f.writePadding(f.wid)
|
|
}
|
|
return
|
|
}
|
|
// Handle padding to the left.
|
|
if f.widPresent && f.wid > width && !f.minus {
|
|
f.writePadding(f.wid - width)
|
|
}
|
|
// Write the encoding directly into the output buffer.
|
|
buf := f.buf
|
|
if f.sharp {
|
|
// Add leading 0x or 0X.
|
|
buf.WriteByte('0')
|
|
buf.WriteByte(digits[16])
|
|
}
|
|
var c byte
|
|
for i := 0; i < length; i++ {
|
|
if f.space && i > 0 {
|
|
// Separate elements with a space.
|
|
buf.WriteByte(' ')
|
|
if f.sharp {
|
|
// Add leading 0x or 0X for each element.
|
|
buf.WriteByte('0')
|
|
buf.WriteByte(digits[16])
|
|
}
|
|
}
|
|
if b != nil {
|
|
c = b[i] // Take a byte from the input byte slice.
|
|
} else {
|
|
c = s[i] // Take a byte from the input string.
|
|
}
|
|
// Encode each byte as two hexadecimal digits.
|
|
buf.WriteByte(digits[c>>4])
|
|
buf.WriteByte(digits[c&0xF])
|
|
}
|
|
// Handle padding to the right.
|
|
if f.widPresent && f.wid > width && f.minus {
|
|
f.writePadding(f.wid - width)
|
|
}
|
|
}
|
|
|
|
// fmt_sx formats a string as a hexadecimal encoding of its bytes.
|
|
func (f *formatInfo) fmt_sx(s, digits string) {
|
|
f.fmt_sbx(s, nil, digits)
|
|
}
|
|
|
|
// fmt_bx formats a byte slice as a hexadecimal encoding of its bytes.
|
|
func (f *formatInfo) fmt_bx(b []byte, digits string) {
|
|
f.fmt_sbx("", b, digits)
|
|
}
|
|
|
|
// fmt_q formats a string as a double-quoted, escaped Go string constant.
|
|
// If f.sharp is set a raw (backquoted) string may be returned instead
|
|
// if the string does not contain any control characters other than tab.
|
|
func (f *formatInfo) fmt_q(s string) {
|
|
s = f.truncate(s)
|
|
if f.sharp && strconv.CanBackquote(s) {
|
|
f.padString("`" + s + "`")
|
|
return
|
|
}
|
|
buf := f.intbuf[:0]
|
|
if f.plus {
|
|
f.pad(strconv.AppendQuoteToASCII(buf, s))
|
|
} else {
|
|
f.pad(strconv.AppendQuote(buf, s))
|
|
}
|
|
}
|
|
|
|
// fmt_c formats an integer as a Unicode character.
|
|
// If the character is not valid Unicode, it will print '\ufffd'.
|
|
func (f *formatInfo) fmt_c(c uint64) {
|
|
r := rune(c)
|
|
if c > utf8.MaxRune {
|
|
r = utf8.RuneError
|
|
}
|
|
buf := f.intbuf[:0]
|
|
w := utf8.EncodeRune(buf[:utf8.UTFMax], r)
|
|
f.pad(buf[:w])
|
|
}
|
|
|
|
// fmt_qc formats an integer as a single-quoted, escaped Go character constant.
|
|
// If the character is not valid Unicode, it will print '\ufffd'.
|
|
func (f *formatInfo) fmt_qc(c uint64) {
|
|
r := rune(c)
|
|
if c > utf8.MaxRune {
|
|
r = utf8.RuneError
|
|
}
|
|
buf := f.intbuf[:0]
|
|
if f.plus {
|
|
f.pad(strconv.AppendQuoteRuneToASCII(buf, r))
|
|
} else {
|
|
f.pad(strconv.AppendQuoteRune(buf, r))
|
|
}
|
|
}
|
|
|
|
// fmt_float formats a float64. It assumes that verb is a valid format specifier
|
|
// for strconv.AppendFloat and therefore fits into a byte.
|
|
func (f *formatInfo) fmt_float(v float64, size int, verb rune, prec int) {
|
|
// Explicit precision in format specifier overrules default precision.
|
|
if f.precPresent {
|
|
prec = f.prec
|
|
}
|
|
// Format number, reserving space for leading + sign if needed.
|
|
num := strconv.AppendFloat(f.intbuf[:1], v, byte(verb), prec, size)
|
|
if num[1] == '-' || num[1] == '+' {
|
|
num = num[1:]
|
|
} else {
|
|
num[0] = '+'
|
|
}
|
|
// f.space means to add a leading space instead of a "+" sign unless
|
|
// the sign is explicitly asked for by f.plus.
|
|
if f.space && num[0] == '+' && !f.plus {
|
|
num[0] = ' '
|
|
}
|
|
// Special handling for infinities and NaN,
|
|
// which don't look like a number so shouldn't be padded with zeros.
|
|
if num[1] == 'I' || num[1] == 'N' {
|
|
oldZero := f.zero
|
|
f.zero = false
|
|
// Remove sign before NaN if not asked for.
|
|
if num[1] == 'N' && !f.space && !f.plus {
|
|
num = num[1:]
|
|
}
|
|
f.pad(num)
|
|
f.zero = oldZero
|
|
return
|
|
}
|
|
// The sharp flag forces printing a decimal point for non-binary formats
|
|
// and retains trailing zeros, which we may need to restore.
|
|
if f.sharp && verb != 'b' {
|
|
digits := 0
|
|
switch verb {
|
|
case 'v', 'g', 'G':
|
|
digits = prec
|
|
// If no precision is set explicitly use a precision of 6.
|
|
if digits == -1 {
|
|
digits = 6
|
|
}
|
|
}
|
|
|
|
// Buffer pre-allocated with enough room for
|
|
// exponent notations of the form "e+123".
|
|
var tailBuf [5]byte
|
|
tail := tailBuf[:0]
|
|
|
|
hasDecimalPoint := false
|
|
// Starting from i = 1 to skip sign at num[0].
|
|
for i := 1; i < len(num); i++ {
|
|
switch num[i] {
|
|
case '.':
|
|
hasDecimalPoint = true
|
|
case 'e', 'E':
|
|
tail = append(tail, num[i:]...)
|
|
num = num[:i]
|
|
default:
|
|
digits--
|
|
}
|
|
}
|
|
if !hasDecimalPoint {
|
|
num = append(num, '.')
|
|
}
|
|
for digits > 0 {
|
|
num = append(num, '0')
|
|
digits--
|
|
}
|
|
num = append(num, tail...)
|
|
}
|
|
// We want a sign if asked for and if the sign is not positive.
|
|
if f.plus || num[0] != '+' {
|
|
// If we're zero padding to the left we want the sign before the leading zeros.
|
|
// Achieve this by writing the sign out and then padding the unsigned number.
|
|
if f.zero && f.widPresent && f.wid > len(num) {
|
|
f.buf.WriteByte(num[0])
|
|
f.writePadding(f.wid - len(num))
|
|
f.buf.Write(num[1:])
|
|
return
|
|
}
|
|
f.pad(num)
|
|
return
|
|
}
|
|
// No sign to show and the number is positive; just print the unsigned number.
|
|
f.pad(num[1:])
|
|
}
|