300 lines
6.6 KiB
Go
Vendored
300 lines
6.6 KiB
Go
Vendored
// Copyright 2013 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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package japanese
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import (
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"unicode/utf8"
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"golang.org/x/text/encoding"
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"golang.org/x/text/encoding/internal"
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"golang.org/x/text/encoding/internal/identifier"
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"golang.org/x/text/transform"
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)
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// ISO2022JP is the ISO-2022-JP encoding.
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var ISO2022JP encoding.Encoding = &iso2022JP
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var iso2022JP = internal.Encoding{
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internal.FuncEncoding{iso2022JPNewDecoder, iso2022JPNewEncoder},
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"ISO-2022-JP",
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identifier.ISO2022JP,
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}
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func iso2022JPNewDecoder() transform.Transformer {
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return new(iso2022JPDecoder)
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}
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func iso2022JPNewEncoder() transform.Transformer {
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return new(iso2022JPEncoder)
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}
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const (
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asciiState = iota
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katakanaState
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jis0208State
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jis0212State
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)
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const asciiEsc = 0x1b
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type iso2022JPDecoder int
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func (d *iso2022JPDecoder) Reset() {
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*d = asciiState
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}
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func (d *iso2022JPDecoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
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r, size := rune(0), 0
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for ; nSrc < len(src); nSrc += size {
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c0 := src[nSrc]
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if c0 >= utf8.RuneSelf {
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r, size = '\ufffd', 1
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goto write
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}
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if c0 == asciiEsc {
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if nSrc+2 >= len(src) {
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if !atEOF {
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return nDst, nSrc, transform.ErrShortSrc
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}
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// TODO: is it correct to only skip 1??
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r, size = '\ufffd', 1
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goto write
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}
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size = 3
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c1 := src[nSrc+1]
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c2 := src[nSrc+2]
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switch {
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case c1 == '$' && (c2 == '@' || c2 == 'B'): // 0x24 {0x40, 0x42}
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*d = jis0208State
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continue
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case c1 == '$' && c2 == '(': // 0x24 0x28
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if nSrc+3 >= len(src) {
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if !atEOF {
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return nDst, nSrc, transform.ErrShortSrc
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}
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r, size = '\ufffd', 1
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goto write
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}
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size = 4
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if src[nSrc+3] == 'D' {
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*d = jis0212State
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continue
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}
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case c1 == '(' && (c2 == 'B' || c2 == 'J'): // 0x28 {0x42, 0x4A}
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*d = asciiState
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continue
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case c1 == '(' && c2 == 'I': // 0x28 0x49
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*d = katakanaState
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continue
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}
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r, size = '\ufffd', 1
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goto write
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}
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switch *d {
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case asciiState:
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r, size = rune(c0), 1
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case katakanaState:
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if c0 < 0x21 || 0x60 <= c0 {
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r, size = '\ufffd', 1
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goto write
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}
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r, size = rune(c0)+(0xff61-0x21), 1
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default:
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if c0 == 0x0a {
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*d = asciiState
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r, size = rune(c0), 1
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goto write
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}
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if nSrc+1 >= len(src) {
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if !atEOF {
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return nDst, nSrc, transform.ErrShortSrc
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}
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r, size = '\ufffd', 1
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goto write
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}
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size = 2
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c1 := src[nSrc+1]
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i := int(c0-0x21)*94 + int(c1-0x21)
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if *d == jis0208State && i < len(jis0208Decode) {
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r = rune(jis0208Decode[i])
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} else if *d == jis0212State && i < len(jis0212Decode) {
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r = rune(jis0212Decode[i])
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} else {
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r = '\ufffd'
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goto write
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}
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if r == 0 {
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r = '\ufffd'
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}
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}
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write:
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if nDst+utf8.RuneLen(r) > len(dst) {
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return nDst, nSrc, transform.ErrShortDst
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}
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nDst += utf8.EncodeRune(dst[nDst:], r)
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}
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return nDst, nSrc, err
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}
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type iso2022JPEncoder int
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func (e *iso2022JPEncoder) Reset() {
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*e = asciiState
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}
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func (e *iso2022JPEncoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
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r, size := rune(0), 0
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for ; nSrc < len(src); nSrc += size {
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r = rune(src[nSrc])
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// Decode a 1-byte rune.
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if r < utf8.RuneSelf {
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size = 1
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} else {
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// Decode a multi-byte rune.
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r, size = utf8.DecodeRune(src[nSrc:])
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if size == 1 {
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// All valid runes of size 1 (those below utf8.RuneSelf) were
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// handled above. We have invalid UTF-8 or we haven't seen the
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// full character yet.
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if !atEOF && !utf8.FullRune(src[nSrc:]) {
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err = transform.ErrShortSrc
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break
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}
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}
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// func init checks that the switch covers all tables.
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//
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// http://encoding.spec.whatwg.org/#iso-2022-jp says that "the index jis0212
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// is not used by the iso-2022-jp encoder due to lack of widespread support".
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//
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// TODO: do we have to special-case U+00A5 and U+203E, as per
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// http://encoding.spec.whatwg.org/#iso-2022-jp
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// Doing so would mean that "\u00a5" would not be preserved
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// after an encode-decode round trip.
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switch {
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case encode0Low <= r && r < encode0High:
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if r = rune(encode0[r-encode0Low]); r>>tableShift == jis0208 {
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goto writeJIS
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}
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case encode1Low <= r && r < encode1High:
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if r = rune(encode1[r-encode1Low]); r>>tableShift == jis0208 {
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goto writeJIS
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}
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case encode2Low <= r && r < encode2High:
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if r = rune(encode2[r-encode2Low]); r>>tableShift == jis0208 {
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goto writeJIS
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}
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case encode3Low <= r && r < encode3High:
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if r = rune(encode3[r-encode3Low]); r>>tableShift == jis0208 {
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goto writeJIS
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}
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case encode4Low <= r && r < encode4High:
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if r = rune(encode4[r-encode4Low]); r>>tableShift == jis0208 {
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goto writeJIS
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}
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case encode5Low <= r && r < encode5High:
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if 0xff61 <= r && r < 0xffa0 {
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goto writeKatakana
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}
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if r = rune(encode5[r-encode5Low]); r>>tableShift == jis0208 {
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goto writeJIS
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}
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}
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// Switch back to ASCII state in case of error so that an ASCII
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// replacement character can be written in the correct state.
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if *e != asciiState {
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if nDst+3 > len(dst) {
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err = transform.ErrShortDst
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break
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}
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*e = asciiState
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dst[nDst+0] = asciiEsc
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dst[nDst+1] = '('
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dst[nDst+2] = 'B'
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nDst += 3
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}
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err = internal.ErrASCIIReplacement
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break
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}
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if *e != asciiState {
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if nDst+4 > len(dst) {
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err = transform.ErrShortDst
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break
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}
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*e = asciiState
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dst[nDst+0] = asciiEsc
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dst[nDst+1] = '('
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dst[nDst+2] = 'B'
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nDst += 3
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} else if nDst >= len(dst) {
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err = transform.ErrShortDst
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break
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}
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dst[nDst] = uint8(r)
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nDst++
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continue
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writeJIS:
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if *e != jis0208State {
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if nDst+5 > len(dst) {
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err = transform.ErrShortDst
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break
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}
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*e = jis0208State
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dst[nDst+0] = asciiEsc
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dst[nDst+1] = '$'
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dst[nDst+2] = 'B'
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nDst += 3
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} else if nDst+2 > len(dst) {
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err = transform.ErrShortDst
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break
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}
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dst[nDst+0] = 0x21 + uint8(r>>codeShift)&codeMask
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dst[nDst+1] = 0x21 + uint8(r)&codeMask
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nDst += 2
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continue
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writeKatakana:
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if *e != katakanaState {
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if nDst+4 > len(dst) {
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err = transform.ErrShortDst
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break
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}
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*e = katakanaState
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dst[nDst+0] = asciiEsc
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dst[nDst+1] = '('
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dst[nDst+2] = 'I'
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nDst += 3
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} else if nDst >= len(dst) {
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err = transform.ErrShortDst
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break
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}
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dst[nDst] = uint8(r - (0xff61 - 0x21))
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nDst++
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continue
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}
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if atEOF && err == nil && *e != asciiState {
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if nDst+3 > len(dst) {
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err = transform.ErrShortDst
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} else {
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*e = asciiState
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dst[nDst+0] = asciiEsc
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dst[nDst+1] = '('
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dst[nDst+2] = 'B'
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nDst += 3
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}
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}
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return nDst, nSrc, err
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}
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