210 lines
6.3 KiB
Go
210 lines
6.3 KiB
Go
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:generate go run gen.go
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// Package ianaindex maps names to Encodings as specified by the IANA registry.
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// This includes both the MIME and IANA names.
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//
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// See http://www.iana.org/assignments/character-sets/character-sets.xhtml for
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// more details.
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package ianaindex
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import (
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"errors"
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"sort"
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"strings"
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"golang.org/x/text/encoding"
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"golang.org/x/text/encoding/charmap"
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"golang.org/x/text/encoding/internal/identifier"
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"golang.org/x/text/encoding/japanese"
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"golang.org/x/text/encoding/korean"
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"golang.org/x/text/encoding/simplifiedchinese"
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"golang.org/x/text/encoding/traditionalchinese"
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"golang.org/x/text/encoding/unicode"
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)
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// TODO: remove the "Status... incomplete" in the package doc comment.
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// TODO: allow users to specify their own aliases?
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// TODO: allow users to specify their own indexes?
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// TODO: allow canonicalizing names
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// NOTE: only use these top-level variables if we can get the linker to drop
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// the indexes when they are not used. Make them a function or perhaps only
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// support MIME otherwise.
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var (
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// MIME is an index to map MIME names.
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MIME *Index = mime
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// IANA is an index that supports all names and aliases using IANA names as
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// the canonical identifier.
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IANA *Index = iana
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// MIB is an index that associates the MIB display name with an Encoding.
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MIB *Index = mib
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mime = &Index{mimeName, ianaToMIB, ianaAliases, encodings[:]}
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iana = &Index{ianaName, ianaToMIB, ianaAliases, encodings[:]}
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mib = &Index{mibName, ianaToMIB, ianaAliases, encodings[:]}
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)
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// Index maps names registered by IANA to Encodings.
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// Currently different Indexes only differ in the names they return for
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// encodings. In the future they may also differ in supported aliases.
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type Index struct {
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names func(i int) string
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toMIB []identifier.MIB // Sorted slice of supported MIBs
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alias map[string]int
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enc []encoding.Encoding
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}
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var (
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errInvalidName = errors.New("ianaindex: invalid encoding name")
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errUnknown = errors.New("ianaindex: unknown Encoding")
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errUnsupported = errors.New("ianaindex: unsupported Encoding")
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)
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// Encoding returns an Encoding for IANA-registered names. Matching is
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// case-insensitive.
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func (x *Index) Encoding(name string) (encoding.Encoding, error) {
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name = strings.TrimSpace(name)
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// First try without lowercasing (possibly creating an allocation).
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i, ok := x.alias[name]
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if !ok {
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i, ok = x.alias[strings.ToLower(name)]
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if !ok {
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return nil, errInvalidName
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}
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}
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return x.enc[i], nil
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}
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// Name reports the canonical name of the given Encoding. It will return an
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// error if the e is not associated with a known encoding scheme.
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func (x *Index) Name(e encoding.Encoding) (string, error) {
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id, ok := e.(identifier.Interface)
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if !ok {
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return "", errUnknown
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}
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mib, _ := id.ID()
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if mib == 0 {
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return "", errUnknown
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}
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v := findMIB(x.toMIB, mib)
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if v == -1 {
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return "", errUnsupported
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}
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return x.names(v), nil
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}
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// TODO: the coverage of this index is rather spotty. Allowing users to set
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// encodings would allow:
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// - users to increase coverage
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// - allow a partially loaded set of encodings in case the user doesn't need to
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// them all.
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// - write an OS-specific wrapper for supported encodings and set them.
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// The exact definition of Set depends a bit on if and how we want to let users
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// write their own Encoding implementations. Also, it is not possible yet to
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// only partially load the encodings without doing some refactoring. Until this
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// is solved, we might as well not support Set.
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// // Set sets the e to be used for the encoding scheme identified by name. Only
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// // canonical names may be used. An empty name assigns e to its internally
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// // associated encoding scheme.
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// func (x *Index) Set(name string, e encoding.Encoding) error {
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// panic("TODO: implement")
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// }
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func findMIB(x []identifier.MIB, mib identifier.MIB) int {
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i := sort.Search(len(x), func(i int) bool { return x[i] >= mib })
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if i < len(x) && x[i] == mib {
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return i
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}
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return -1
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}
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const maxMIMENameLen = '0' - 1 // officially 40, but we leave some buffer.
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func mimeName(x int) string {
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n := ianaNames[x]
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// See gen.go for a description of the encoding.
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if n[0] <= maxMIMENameLen {
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return n[1:n[0]]
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}
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return n
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}
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func ianaName(x int) string {
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n := ianaNames[x]
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// See gen.go for a description of the encoding.
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if n[0] <= maxMIMENameLen {
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return n[n[0]:]
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}
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return n
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}
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func mibName(x int) string {
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return mibNames[x]
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}
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var encodings = [numIANA]encoding.Encoding{
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enc106: unicode.UTF8,
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enc1015: unicode.UTF16(unicode.BigEndian, unicode.UseBOM),
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enc1013: unicode.UTF16(unicode.BigEndian, unicode.IgnoreBOM),
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enc1014: unicode.UTF16(unicode.LittleEndian, unicode.IgnoreBOM),
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enc2028: charmap.CodePage037,
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enc2011: charmap.CodePage437,
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enc2009: charmap.CodePage850,
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enc2010: charmap.CodePage852,
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enc2046: charmap.CodePage855,
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enc2089: charmap.CodePage858,
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enc2048: charmap.CodePage860,
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enc2013: charmap.CodePage862,
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enc2050: charmap.CodePage863,
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enc2052: charmap.CodePage865,
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enc2086: charmap.CodePage866,
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enc2102: charmap.CodePage1047,
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enc2091: charmap.CodePage1140,
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enc4: charmap.ISO8859_1,
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enc5: charmap.ISO8859_2,
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enc6: charmap.ISO8859_3,
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enc7: charmap.ISO8859_4,
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enc8: charmap.ISO8859_5,
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enc9: charmap.ISO8859_6,
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enc81: charmap.ISO8859_6E,
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enc82: charmap.ISO8859_6I,
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enc10: charmap.ISO8859_7,
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enc11: charmap.ISO8859_8,
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enc84: charmap.ISO8859_8E,
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enc85: charmap.ISO8859_8I,
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enc12: charmap.ISO8859_9,
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enc13: charmap.ISO8859_10,
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enc109: charmap.ISO8859_13,
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enc110: charmap.ISO8859_14,
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enc111: charmap.ISO8859_15,
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enc112: charmap.ISO8859_16,
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enc2084: charmap.KOI8R,
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enc2088: charmap.KOI8U,
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enc2027: charmap.Macintosh,
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enc2109: charmap.Windows874,
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enc2250: charmap.Windows1250,
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enc2251: charmap.Windows1251,
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enc2252: charmap.Windows1252,
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enc2253: charmap.Windows1253,
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enc2254: charmap.Windows1254,
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enc2255: charmap.Windows1255,
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enc2256: charmap.Windows1256,
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enc2257: charmap.Windows1257,
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enc2258: charmap.Windows1258,
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enc18: japanese.EUCJP,
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enc39: japanese.ISO2022JP,
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enc17: japanese.ShiftJIS,
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enc38: korean.EUCKR,
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enc114: simplifiedchinese.GB18030,
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enc113: simplifiedchinese.GBK,
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enc2085: simplifiedchinese.HZGB2312,
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enc2026: traditionalchinese.Big5,
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}
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