rss-tools/vendor/golang.org/x/text/encoding/simplifiedchinese/gbk.go (view raw)
| 1 | // Copyright 2013 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package simplifiedchinese |
| 6 | |
| 7 | import ( |
| 8 | "unicode/utf8" |
| 9 | |
| 10 | "golang.org/x/text/encoding" |
| 11 | "golang.org/x/text/encoding/internal" |
| 12 | "golang.org/x/text/encoding/internal/identifier" |
| 13 | "golang.org/x/text/transform" |
| 14 | ) |
| 15 | |
| 16 | var ( |
| 17 | // GB18030 is the GB18030 encoding. |
| 18 | GB18030 encoding.Encoding = &gbk18030 |
| 19 | // GBK is the GBK encoding. It encodes an extension of the GB2312 character set |
| 20 | // and is also known as Code Page 936. |
| 21 | GBK encoding.Encoding = &gbk |
| 22 | ) |
| 23 | |
| 24 | var gbk = internal.Encoding{ |
| 25 | Encoding: &internal.SimpleEncoding{ |
| 26 | Decoder: gbkDecoder{gb18030: false}, |
| 27 | Encoder: gbkEncoder{gb18030: false}, |
| 28 | }, |
| 29 | Name: "GBK", |
| 30 | MIB: identifier.GBK, |
| 31 | } |
| 32 | |
| 33 | var gbk18030 = internal.Encoding{ |
| 34 | Encoding: &internal.SimpleEncoding{ |
| 35 | Decoder: gbkDecoder{gb18030: true}, |
| 36 | Encoder: gbkEncoder{gb18030: true}, |
| 37 | }, |
| 38 | Name: "GB18030", |
| 39 | MIB: identifier.GB18030, |
| 40 | } |
| 41 | |
| 42 | type gbkDecoder struct { |
| 43 | transform.NopResetter |
| 44 | gb18030 bool |
| 45 | } |
| 46 | |
| 47 | func (d gbkDecoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) { |
| 48 | r, size := rune(0), 0 |
| 49 | loop: |
| 50 | for ; nSrc < len(src); nSrc += size { |
| 51 | switch c0 := src[nSrc]; { |
| 52 | case c0 < utf8.RuneSelf: |
| 53 | r, size = rune(c0), 1 |
| 54 | |
| 55 | // Microsoft's Code Page 936 extends GBK 1.0 to encode the euro sign U+20AC |
| 56 | // as 0x80. The HTML5 specification at http://encoding.spec.whatwg.org/#gbk |
| 57 | // says to treat "gbk" as Code Page 936. |
| 58 | // GBK’s decoder is gb18030’s decoder. https://encoding.spec.whatwg.org/#gbk-decoder |
| 59 | // If byte is 0x80, return code point U+20AC. https://encoding.spec.whatwg.org/#gb18030-decoder |
| 60 | case c0 == 0x80: |
| 61 | r, size = '€', 1 |
| 62 | |
| 63 | case c0 < 0xff: |
| 64 | if nSrc+1 >= len(src) { |
| 65 | if !atEOF { |
| 66 | err = transform.ErrShortSrc |
| 67 | break loop |
| 68 | } |
| 69 | r, size = utf8.RuneError, 1 |
| 70 | goto write |
| 71 | } |
| 72 | c1 := src[nSrc+1] |
| 73 | switch { |
| 74 | case 0x40 <= c1 && c1 < 0x7f: |
| 75 | c1 -= 0x40 |
| 76 | case 0x80 <= c1 && c1 < 0xff: |
| 77 | c1 -= 0x41 |
| 78 | case d.gb18030 && 0x30 <= c1 && c1 < 0x40: |
| 79 | if nSrc+3 >= len(src) { |
| 80 | if !atEOF { |
| 81 | err = transform.ErrShortSrc |
| 82 | break loop |
| 83 | } |
| 84 | // The second byte here is always ASCII, so we can set size |
| 85 | // to 1 in all cases. |
| 86 | r, size = utf8.RuneError, 1 |
| 87 | goto write |
| 88 | } |
| 89 | c2 := src[nSrc+2] |
| 90 | if c2 < 0x81 || 0xff <= c2 { |
| 91 | r, size = utf8.RuneError, 1 |
| 92 | goto write |
| 93 | } |
| 94 | c3 := src[nSrc+3] |
| 95 | if c3 < 0x30 || 0x3a <= c3 { |
| 96 | r, size = utf8.RuneError, 1 |
| 97 | goto write |
| 98 | } |
| 99 | size = 4 |
| 100 | r = ((rune(c0-0x81)*10+rune(c1-0x30))*126+rune(c2-0x81))*10 + rune(c3-0x30) |
| 101 | if r < 39420 { |
| 102 | i, j := 0, len(gb18030) |
| 103 | for i < j { |
| 104 | h := i + (j-i)/2 |
| 105 | if r >= rune(gb18030[h][0]) { |
| 106 | i = h + 1 |
| 107 | } else { |
| 108 | j = h |
| 109 | } |
| 110 | } |
| 111 | dec := &gb18030[i-1] |
| 112 | r += rune(dec[1]) - rune(dec[0]) |
| 113 | goto write |
| 114 | } |
| 115 | r -= 189000 |
| 116 | if 0 <= r && r < 0x100000 { |
| 117 | r += 0x10000 |
| 118 | } else { |
| 119 | r, size = utf8.RuneError, 1 |
| 120 | } |
| 121 | goto write |
| 122 | default: |
| 123 | r, size = utf8.RuneError, 1 |
| 124 | goto write |
| 125 | } |
| 126 | r, size = '\ufffd', 2 |
| 127 | if i := int(c0-0x81)*190 + int(c1); i < len(decode) { |
| 128 | r = rune(decode[i]) |
| 129 | if r == 0 { |
| 130 | r = '\ufffd' |
| 131 | } |
| 132 | } |
| 133 | |
| 134 | default: |
| 135 | r, size = utf8.RuneError, 1 |
| 136 | } |
| 137 | |
| 138 | write: |
| 139 | if nDst+utf8.RuneLen(r) > len(dst) { |
| 140 | err = transform.ErrShortDst |
| 141 | break loop |
| 142 | } |
| 143 | nDst += utf8.EncodeRune(dst[nDst:], r) |
| 144 | } |
| 145 | return nDst, nSrc, err |
| 146 | } |
| 147 | |
| 148 | type gbkEncoder struct { |
| 149 | transform.NopResetter |
| 150 | gb18030 bool |
| 151 | } |
| 152 | |
| 153 | func (e gbkEncoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) { |
| 154 | r, r2, size := rune(0), rune(0), 0 |
| 155 | for ; nSrc < len(src); nSrc += size { |
| 156 | r = rune(src[nSrc]) |
| 157 | |
| 158 | // Decode a 1-byte rune. |
| 159 | if r < utf8.RuneSelf { |
| 160 | size = 1 |
| 161 | |
| 162 | } else { |
| 163 | // Decode a multi-byte rune. |
| 164 | r, size = utf8.DecodeRune(src[nSrc:]) |
| 165 | if size == 1 { |
| 166 | // All valid runes of size 1 (those below utf8.RuneSelf) were |
| 167 | // handled above. We have invalid UTF-8 or we haven't seen the |
| 168 | // full character yet. |
| 169 | if !atEOF && !utf8.FullRune(src[nSrc:]) { |
| 170 | err = transform.ErrShortSrc |
| 171 | break |
| 172 | } |
| 173 | } |
| 174 | |
| 175 | // func init checks that the switch covers all tables. |
| 176 | switch { |
| 177 | case encode0Low <= r && r < encode0High: |
| 178 | if r2 = rune(encode0[r-encode0Low]); r2 != 0 { |
| 179 | goto write2 |
| 180 | } |
| 181 | case encode1Low <= r && r < encode1High: |
| 182 | // Microsoft's Code Page 936 extends GBK 1.0 to encode the euro sign U+20AC |
| 183 | // as 0x80. The HTML5 specification at http://encoding.spec.whatwg.org/#gbk |
| 184 | // says to treat "gbk" as Code Page 936. |
| 185 | // GBK’s encoder is gb18030’s encoder with its _is GBK_ set to true. https://encoding.spec.whatwg.org/#gbk-encoder |
| 186 | // If _is GBK_ is true and code point is U+20AC, return byte 0x80. https://encoding.spec.whatwg.org/#gb18030-encoder |
| 187 | if !e.gb18030 && r == '€' { |
| 188 | r = 0x80 |
| 189 | goto write1 |
| 190 | } |
| 191 | if r2 = rune(encode1[r-encode1Low]); r2 != 0 { |
| 192 | goto write2 |
| 193 | } |
| 194 | case encode2Low <= r && r < encode2High: |
| 195 | if r2 = rune(encode2[r-encode2Low]); r2 != 0 { |
| 196 | goto write2 |
| 197 | } |
| 198 | case encode3Low <= r && r < encode3High: |
| 199 | if r2 = rune(encode3[r-encode3Low]); r2 != 0 { |
| 200 | goto write2 |
| 201 | } |
| 202 | case encode4Low <= r && r < encode4High: |
| 203 | if r2 = rune(encode4[r-encode4Low]); r2 != 0 { |
| 204 | goto write2 |
| 205 | } |
| 206 | } |
| 207 | |
| 208 | if e.gb18030 { |
| 209 | if r < 0x10000 { |
| 210 | i, j := 0, len(gb18030) |
| 211 | for i < j { |
| 212 | h := i + (j-i)/2 |
| 213 | if r >= rune(gb18030[h][1]) { |
| 214 | i = h + 1 |
| 215 | } else { |
| 216 | j = h |
| 217 | } |
| 218 | } |
| 219 | dec := &gb18030[i-1] |
| 220 | r += rune(dec[0]) - rune(dec[1]) |
| 221 | goto write4 |
| 222 | } else if r < 0x110000 { |
| 223 | r += 189000 - 0x10000 |
| 224 | goto write4 |
| 225 | } |
| 226 | } |
| 227 | err = internal.ErrASCIIReplacement |
| 228 | break |
| 229 | } |
| 230 | |
| 231 | write1: |
| 232 | if nDst >= len(dst) { |
| 233 | err = transform.ErrShortDst |
| 234 | break |
| 235 | } |
| 236 | dst[nDst] = uint8(r) |
| 237 | nDst++ |
| 238 | continue |
| 239 | |
| 240 | write2: |
| 241 | if nDst+2 > len(dst) { |
| 242 | err = transform.ErrShortDst |
| 243 | break |
| 244 | } |
| 245 | dst[nDst+0] = uint8(r2 >> 8) |
| 246 | dst[nDst+1] = uint8(r2) |
| 247 | nDst += 2 |
| 248 | continue |
| 249 | |
| 250 | write4: |
| 251 | if nDst+4 > len(dst) { |
| 252 | err = transform.ErrShortDst |
| 253 | break |
| 254 | } |
| 255 | dst[nDst+3] = uint8(r%10 + 0x30) |
| 256 | r /= 10 |
| 257 | dst[nDst+2] = uint8(r%126 + 0x81) |
| 258 | r /= 126 |
| 259 | dst[nDst+1] = uint8(r%10 + 0x30) |
| 260 | r /= 10 |
| 261 | dst[nDst+0] = uint8(r + 0x81) |
| 262 | nDst += 4 |
| 263 | continue |
| 264 | } |
| 265 | return nDst, nSrc, err |
| 266 | } |
| 267 | |
| 268 | func init() { |
| 269 | // Check that the hard-coded encode switch covers all tables. |
| 270 | if numEncodeTables != 5 { |
| 271 | panic("bad numEncodeTables") |
| 272 | } |
| 273 | } |