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