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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 simplifiedchinese
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"
)
// HZGB2312 is the HZ-GB2312 encoding.
var HZGB2312 encoding.Encoding = &hzGB2312
var hzGB2312 = internal.Encoding{
internal.FuncEncoding{hzGB2312NewDecoder, hzGB2312NewEncoder},
"HZ-GB2312",
identifier.HZGB2312,
}
func hzGB2312NewDecoder() transform.Transformer {
return new(hzGB2312Decoder)
}
func hzGB2312NewEncoder() transform.Transformer {
return new(hzGB2312Encoder)
}
const (
asciiState = iota
gbState
)
type hzGB2312Decoder int
func (d *hzGB2312Decoder) Reset() {
*d = asciiState
}
func (d *hzGB2312Decoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
r, size := rune(0), 0
loop:
for ; nSrc < len(src); nSrc += size {
c0 := src[nSrc]
if c0 >= utf8.RuneSelf {
r, size = utf8.RuneError, 1
goto write
}
if c0 == '~' {
if nSrc+1 >= len(src) {
if !atEOF {
err = transform.ErrShortSrc
break loop
}
r = utf8.RuneError
goto write
}
size = 2
switch src[nSrc+1] {
case '{':
*d = gbState
continue
case '}':
*d = asciiState
continue
case '~':
if nDst >= len(dst) {
err = transform.ErrShortDst
break loop
}
dst[nDst] = '~'
nDst++
continue
case '\n':
continue
default:
r = utf8.RuneError
goto write
}
}
if *d == asciiState {
r, size = rune(c0), 1
} else {
if nSrc+1 >= len(src) {
if !atEOF {
err = transform.ErrShortSrc
break loop
}
r, size = utf8.RuneError, 1
goto write
}
size = 2
c1 := src[nSrc+1]
if c0 < 0x21 || 0x7e <= c0 || c1 < 0x21 || 0x7f <= c1 {
// error
} else if i := int(c0-0x01)*190 + int(c1+0x3f); i < len(decode) {
r = rune(decode[i])
if r != 0 {
goto write
}
}
if c1 > utf8.RuneSelf {
// Be consistent and always treat non-ASCII as a single error.
size = 1
}
r = utf8.RuneError
}
write:
if nDst+utf8.RuneLen(r) > len(dst) {
err = transform.ErrShortDst
break loop
}
nDst += utf8.EncodeRune(dst[nDst:], r)
}
return nDst, nSrc, err
}
type hzGB2312Encoder int
func (d *hzGB2312Encoder) Reset() {
*d = asciiState
}
func (e *hzGB2312Encoder) 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
if r == '~' {
if nDst+2 > len(dst) {
err = transform.ErrShortDst
break
}
dst[nDst+0] = '~'
dst[nDst+1] = '~'
nDst += 2
continue
} else if *e != asciiState {
if nDst+3 > len(dst) {
err = transform.ErrShortDst
break
}
*e = asciiState
dst[nDst+0] = '~'
dst[nDst+1] = '}'
nDst += 2
} else if nDst >= len(dst) {
err = transform.ErrShortDst
break
}
dst[nDst] = uint8(r)
nDst += 1
continue
}
// 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.
switch {
case encode0Low <= r && r < encode0High:
if r = rune(encode0[r-encode0Low]); r != 0 {
goto writeGB
}
case encode1Low <= r && r < encode1High:
if r = rune(encode1[r-encode1Low]); r != 0 {
goto writeGB
}
case encode2Low <= r && r < encode2High:
if r = rune(encode2[r-encode2Low]); r != 0 {
goto writeGB
}
case encode3Low <= r && r < encode3High:
if r = rune(encode3[r-encode3Low]); r != 0 {
goto writeGB
}
case encode4Low <= r && r < encode4High:
if r = rune(encode4[r-encode4Low]); r != 0 {
goto writeGB
}
}
terminateInASCIIState:
// 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+2 > len(dst) {
err = transform.ErrShortDst
break
}
dst[nDst+0] = '~'
dst[nDst+1] = '}'
nDst += 2
}
err = internal.ErrASCIIReplacement
break
writeGB:
c0 := uint8(r>>8) - 0x80
c1 := uint8(r) - 0x80
if c0 < 0x21 || 0x7e <= c0 || c1 < 0x21 || 0x7f <= c1 {
goto terminateInASCIIState
}
if *e == asciiState {
if nDst+4 > len(dst) {
err = transform.ErrShortDst
break
}
*e = gbState
dst[nDst+0] = '~'
dst[nDst+1] = '{'
nDst += 2
} else if nDst+2 > len(dst) {
err = transform.ErrShortDst
break
}
dst[nDst+0] = c0
dst[nDst+1] = c1
nDst += 2
continue
}
// TODO: should one always terminate in ASCII state to make it safe to
// concatenate two HZ-GB2312-encoded strings?
return nDst, nSrc, err
}
|
