youtubebeat/vendor/golang.org/x/text/encoding/simplifiedchinese/gbk.go

269 lines
5.8 KiB
Go

// 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"
)
var (
// GB18030 is the GB18030 encoding.
GB18030 encoding.Encoding = &gbk18030
// GBK is the GBK encoding. It encodes an extension of the GB2312 character set
// and is also known as Code Page 936.
GBK encoding.Encoding = &gbk
)
var gbk = internal.Encoding{
&internal.SimpleEncoding{
gbkDecoder{gb18030: false},
gbkEncoder{gb18030: false},
},
"GBK",
identifier.GBK,
}
var gbk18030 = internal.Encoding{
&internal.SimpleEncoding{
gbkDecoder{gb18030: true},
gbkEncoder{gb18030: true},
},
"GB18030",
identifier.GB18030,
}
type gbkDecoder struct {
transform.NopResetter
gb18030 bool
}
func (d gbkDecoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
r, size := rune(0), 0
loop:
for ; nSrc < len(src); nSrc += size {
switch c0 := src[nSrc]; {
case c0 < utf8.RuneSelf:
r, size = rune(c0), 1
// Microsoft's Code Page 936 extends GBK 1.0 to encode the euro sign U+20AC
// as 0x80. The HTML5 specification at http://encoding.spec.whatwg.org/#gbk
// says to treat "gbk" as Code Page 936.
case c0 == 0x80:
r, size = '€', 1
case c0 < 0xff:
if nSrc+1 >= len(src) {
if !atEOF {
err = transform.ErrShortSrc
break loop
}
r, size = utf8.RuneError, 1
goto write
}
c1 := src[nSrc+1]
switch {
case 0x40 <= c1 && c1 < 0x7f:
c1 -= 0x40
case 0x80 <= c1 && c1 < 0xff:
c1 -= 0x41
case d.gb18030 && 0x30 <= c1 && c1 < 0x40:
if nSrc+3 >= len(src) {
if !atEOF {
err = transform.ErrShortSrc
break loop
}
// The second byte here is always ASCII, so we can set size
// to 1 in all cases.
r, size = utf8.RuneError, 1
goto write
}
c2 := src[nSrc+2]
if c2 < 0x81 || 0xff <= c2 {
r, size = utf8.RuneError, 1
goto write
}
c3 := src[nSrc+3]
if c3 < 0x30 || 0x3a <= c3 {
r, size = utf8.RuneError, 1
goto write
}
size = 4
r = ((rune(c0-0x81)*10+rune(c1-0x30))*126+rune(c2-0x81))*10 + rune(c3-0x30)
if r < 39420 {
i, j := 0, len(gb18030)
for i < j {
h := i + (j-i)/2
if r >= rune(gb18030[h][0]) {
i = h + 1
} else {
j = h
}
}
dec := &gb18030[i-1]
r += rune(dec[1]) - rune(dec[0])
goto write
}
r -= 189000
if 0 <= r && r < 0x100000 {
r += 0x10000
} else {
r, size = utf8.RuneError, 1
}
goto write
default:
r, size = utf8.RuneError, 1
goto write
}
r, size = '\ufffd', 2
if i := int(c0-0x81)*190 + int(c1); i < len(decode) {
r = rune(decode[i])
if r == 0 {
r = '\ufffd'
}
}
default:
r, size = utf8.RuneError, 1
}
write:
if nDst+utf8.RuneLen(r) > len(dst) {
err = transform.ErrShortDst
break loop
}
nDst += utf8.EncodeRune(dst[nDst:], r)
}
return nDst, nSrc, err
}
type gbkEncoder struct {
transform.NopResetter
gb18030 bool
}
func (e gbkEncoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
r, r2, size := rune(0), 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.
switch {
case encode0Low <= r && r < encode0High:
if r2 = rune(encode0[r-encode0Low]); r2 != 0 {
goto write2
}
case encode1Low <= r && r < encode1High:
// Microsoft's Code Page 936 extends GBK 1.0 to encode the euro sign U+20AC
// as 0x80. The HTML5 specification at http://encoding.spec.whatwg.org/#gbk
// says to treat "gbk" as Code Page 936.
if r == '€' {
r = 0x80
goto write1
}
if r2 = rune(encode1[r-encode1Low]); r2 != 0 {
goto write2
}
case encode2Low <= r && r < encode2High:
if r2 = rune(encode2[r-encode2Low]); r2 != 0 {
goto write2
}
case encode3Low <= r && r < encode3High:
if r2 = rune(encode3[r-encode3Low]); r2 != 0 {
goto write2
}
case encode4Low <= r && r < encode4High:
if r2 = rune(encode4[r-encode4Low]); r2 != 0 {
goto write2
}
}
if e.gb18030 {
if r < 0x10000 {
i, j := 0, len(gb18030)
for i < j {
h := i + (j-i)/2
if r >= rune(gb18030[h][1]) {
i = h + 1
} else {
j = h
}
}
dec := &gb18030[i-1]
r += rune(dec[0]) - rune(dec[1])
goto write4
} else if r < 0x110000 {
r += 189000 - 0x10000
goto write4
}
}
err = internal.ErrASCIIReplacement
break
}
write1:
if nDst >= len(dst) {
err = transform.ErrShortDst
break
}
dst[nDst] = uint8(r)
nDst++
continue
write2:
if nDst+2 > len(dst) {
err = transform.ErrShortDst
break
}
dst[nDst+0] = uint8(r2 >> 8)
dst[nDst+1] = uint8(r2)
nDst += 2
continue
write4:
if nDst+4 > len(dst) {
err = transform.ErrShortDst
break
}
dst[nDst+3] = uint8(r%10 + 0x30)
r /= 10
dst[nDst+2] = uint8(r%126 + 0x81)
r /= 126
dst[nDst+1] = uint8(r%10 + 0x30)
r /= 10
dst[nDst+0] = uint8(r + 0x81)
nDst += 4
continue
}
return nDst, nSrc, err
}
func init() {
// Check that the hard-coded encode switch covers all tables.
if numEncodeTables != 5 {
panic("bad numEncodeTables")
}
}