rss-tools/vendor/golang.org/x/text/encoding/japanese/iso2022jp.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 japanese |
| 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 | // ISO2022JP is the ISO-2022-JP encoding. |
| 17 | var ISO2022JP encoding.Encoding = &iso2022JP |
| 18 | |
| 19 | var iso2022JP = internal.Encoding{ |
| 20 | Encoding: internal.FuncEncoding{Decoder: iso2022JPNewDecoder, Encoder: iso2022JPNewEncoder}, |
| 21 | Name: "ISO-2022-JP", |
| 22 | MIB: identifier.ISO2022JP, |
| 23 | } |
| 24 | |
| 25 | func iso2022JPNewDecoder() transform.Transformer { |
| 26 | return new(iso2022JPDecoder) |
| 27 | } |
| 28 | |
| 29 | func iso2022JPNewEncoder() transform.Transformer { |
| 30 | return new(iso2022JPEncoder) |
| 31 | } |
| 32 | |
| 33 | const ( |
| 34 | asciiState = iota |
| 35 | katakanaState |
| 36 | jis0208State |
| 37 | jis0212State |
| 38 | ) |
| 39 | |
| 40 | const asciiEsc = 0x1b |
| 41 | |
| 42 | type iso2022JPDecoder int |
| 43 | |
| 44 | func (d *iso2022JPDecoder) Reset() { |
| 45 | *d = asciiState |
| 46 | } |
| 47 | |
| 48 | func (d *iso2022JPDecoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) { |
| 49 | r, size := rune(0), 0 |
| 50 | for ; nSrc < len(src); nSrc += size { |
| 51 | c0 := src[nSrc] |
| 52 | if c0 >= utf8.RuneSelf { |
| 53 | r, size = '\ufffd', 1 |
| 54 | goto write |
| 55 | } |
| 56 | |
| 57 | if c0 == asciiEsc { |
| 58 | if nSrc+2 >= len(src) { |
| 59 | if !atEOF { |
| 60 | return nDst, nSrc, transform.ErrShortSrc |
| 61 | } |
| 62 | // TODO: is it correct to only skip 1?? |
| 63 | r, size = '\ufffd', 1 |
| 64 | goto write |
| 65 | } |
| 66 | size = 3 |
| 67 | c1 := src[nSrc+1] |
| 68 | c2 := src[nSrc+2] |
| 69 | switch { |
| 70 | case c1 == '$' && (c2 == '@' || c2 == 'B'): // 0x24 {0x40, 0x42} |
| 71 | *d = jis0208State |
| 72 | continue |
| 73 | case c1 == '$' && c2 == '(': // 0x24 0x28 |
| 74 | if nSrc+3 >= len(src) { |
| 75 | if !atEOF { |
| 76 | return nDst, nSrc, transform.ErrShortSrc |
| 77 | } |
| 78 | r, size = '\ufffd', 1 |
| 79 | goto write |
| 80 | } |
| 81 | size = 4 |
| 82 | if src[nSrc+3] == 'D' { |
| 83 | *d = jis0212State |
| 84 | continue |
| 85 | } |
| 86 | case c1 == '(' && (c2 == 'B' || c2 == 'J'): // 0x28 {0x42, 0x4A} |
| 87 | *d = asciiState |
| 88 | continue |
| 89 | case c1 == '(' && c2 == 'I': // 0x28 0x49 |
| 90 | *d = katakanaState |
| 91 | continue |
| 92 | } |
| 93 | r, size = '\ufffd', 1 |
| 94 | goto write |
| 95 | } |
| 96 | |
| 97 | switch *d { |
| 98 | case asciiState: |
| 99 | r, size = rune(c0), 1 |
| 100 | |
| 101 | case katakanaState: |
| 102 | if c0 < 0x21 || 0x60 <= c0 { |
| 103 | r, size = '\ufffd', 1 |
| 104 | goto write |
| 105 | } |
| 106 | r, size = rune(c0)+(0xff61-0x21), 1 |
| 107 | |
| 108 | default: |
| 109 | if c0 == 0x0a { |
| 110 | *d = asciiState |
| 111 | r, size = rune(c0), 1 |
| 112 | goto write |
| 113 | } |
| 114 | if nSrc+1 >= len(src) { |
| 115 | if !atEOF { |
| 116 | return nDst, nSrc, transform.ErrShortSrc |
| 117 | } |
| 118 | r, size = '\ufffd', 1 |
| 119 | goto write |
| 120 | } |
| 121 | size = 2 |
| 122 | c1 := src[nSrc+1] |
| 123 | i := int(c0-0x21)*94 + int(c1-0x21) |
| 124 | if *d == jis0208State && i < len(jis0208Decode) { |
| 125 | r = rune(jis0208Decode[i]) |
| 126 | } else if *d == jis0212State && i < len(jis0212Decode) { |
| 127 | r = rune(jis0212Decode[i]) |
| 128 | } else { |
| 129 | r = '\ufffd' |
| 130 | goto write |
| 131 | } |
| 132 | if r == 0 { |
| 133 | r = '\ufffd' |
| 134 | } |
| 135 | } |
| 136 | |
| 137 | write: |
| 138 | if nDst+utf8.RuneLen(r) > len(dst) { |
| 139 | return nDst, nSrc, transform.ErrShortDst |
| 140 | } |
| 141 | nDst += utf8.EncodeRune(dst[nDst:], r) |
| 142 | } |
| 143 | return nDst, nSrc, err |
| 144 | } |
| 145 | |
| 146 | type iso2022JPEncoder int |
| 147 | |
| 148 | func (e *iso2022JPEncoder) Reset() { |
| 149 | *e = asciiState |
| 150 | } |
| 151 | |
| 152 | func (e *iso2022JPEncoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) { |
| 153 | r, size := rune(0), 0 |
| 154 | for ; nSrc < len(src); nSrc += size { |
| 155 | r = rune(src[nSrc]) |
| 156 | |
| 157 | // Decode a 1-byte rune. |
| 158 | if r < utf8.RuneSelf { |
| 159 | size = 1 |
| 160 | |
| 161 | } else { |
| 162 | // Decode a multi-byte rune. |
| 163 | r, size = utf8.DecodeRune(src[nSrc:]) |
| 164 | if size == 1 { |
| 165 | // All valid runes of size 1 (those below utf8.RuneSelf) were |
| 166 | // handled above. We have invalid UTF-8 or we haven't seen the |
| 167 | // full character yet. |
| 168 | if !atEOF && !utf8.FullRune(src[nSrc:]) { |
| 169 | err = transform.ErrShortSrc |
| 170 | break |
| 171 | } |
| 172 | } |
| 173 | |
| 174 | // func init checks that the switch covers all tables. |
| 175 | // |
| 176 | // http://encoding.spec.whatwg.org/#iso-2022-jp says that "the index jis0212 |
| 177 | // is not used by the iso-2022-jp encoder due to lack of widespread support". |
| 178 | // |
| 179 | // TODO: do we have to special-case U+00A5 and U+203E, as per |
| 180 | // http://encoding.spec.whatwg.org/#iso-2022-jp |
| 181 | // Doing so would mean that "\u00a5" would not be preserved |
| 182 | // after an encode-decode round trip. |
| 183 | switch { |
| 184 | case encode0Low <= r && r < encode0High: |
| 185 | if r = rune(encode0[r-encode0Low]); r>>tableShift == jis0208 { |
| 186 | goto writeJIS |
| 187 | } |
| 188 | case encode1Low <= r && r < encode1High: |
| 189 | if r = rune(encode1[r-encode1Low]); r>>tableShift == jis0208 { |
| 190 | goto writeJIS |
| 191 | } |
| 192 | case encode2Low <= r && r < encode2High: |
| 193 | if r = rune(encode2[r-encode2Low]); r>>tableShift == jis0208 { |
| 194 | goto writeJIS |
| 195 | } |
| 196 | case encode3Low <= r && r < encode3High: |
| 197 | if r = rune(encode3[r-encode3Low]); r>>tableShift == jis0208 { |
| 198 | goto writeJIS |
| 199 | } |
| 200 | case encode4Low <= r && r < encode4High: |
| 201 | if r = rune(encode4[r-encode4Low]); r>>tableShift == jis0208 { |
| 202 | goto writeJIS |
| 203 | } |
| 204 | case encode5Low <= r && r < encode5High: |
| 205 | if 0xff61 <= r && r < 0xffa0 { |
| 206 | goto writeKatakana |
| 207 | } |
| 208 | if r = rune(encode5[r-encode5Low]); r>>tableShift == jis0208 { |
| 209 | goto writeJIS |
| 210 | } |
| 211 | } |
| 212 | |
| 213 | // Switch back to ASCII state in case of error so that an ASCII |
| 214 | // replacement character can be written in the correct state. |
| 215 | if *e != asciiState { |
| 216 | if nDst+3 > len(dst) { |
| 217 | err = transform.ErrShortDst |
| 218 | break |
| 219 | } |
| 220 | *e = asciiState |
| 221 | dst[nDst+0] = asciiEsc |
| 222 | dst[nDst+1] = '(' |
| 223 | dst[nDst+2] = 'B' |
| 224 | nDst += 3 |
| 225 | } |
| 226 | err = internal.ErrASCIIReplacement |
| 227 | break |
| 228 | } |
| 229 | |
| 230 | if *e != asciiState { |
| 231 | if nDst+4 > len(dst) { |
| 232 | err = transform.ErrShortDst |
| 233 | break |
| 234 | } |
| 235 | *e = asciiState |
| 236 | dst[nDst+0] = asciiEsc |
| 237 | dst[nDst+1] = '(' |
| 238 | dst[nDst+2] = 'B' |
| 239 | nDst += 3 |
| 240 | } else if nDst >= len(dst) { |
| 241 | err = transform.ErrShortDst |
| 242 | break |
| 243 | } |
| 244 | dst[nDst] = uint8(r) |
| 245 | nDst++ |
| 246 | continue |
| 247 | |
| 248 | writeJIS: |
| 249 | if *e != jis0208State { |
| 250 | if nDst+5 > len(dst) { |
| 251 | err = transform.ErrShortDst |
| 252 | break |
| 253 | } |
| 254 | *e = jis0208State |
| 255 | dst[nDst+0] = asciiEsc |
| 256 | dst[nDst+1] = '$' |
| 257 | dst[nDst+2] = 'B' |
| 258 | nDst += 3 |
| 259 | } else if nDst+2 > len(dst) { |
| 260 | err = transform.ErrShortDst |
| 261 | break |
| 262 | } |
| 263 | dst[nDst+0] = 0x21 + uint8(r>>codeShift)&codeMask |
| 264 | dst[nDst+1] = 0x21 + uint8(r)&codeMask |
| 265 | nDst += 2 |
| 266 | continue |
| 267 | |
| 268 | writeKatakana: |
| 269 | if *e != katakanaState { |
| 270 | if nDst+4 > len(dst) { |
| 271 | err = transform.ErrShortDst |
| 272 | break |
| 273 | } |
| 274 | *e = katakanaState |
| 275 | dst[nDst+0] = asciiEsc |
| 276 | dst[nDst+1] = '(' |
| 277 | dst[nDst+2] = 'I' |
| 278 | nDst += 3 |
| 279 | } else if nDst >= len(dst) { |
| 280 | err = transform.ErrShortDst |
| 281 | break |
| 282 | } |
| 283 | dst[nDst] = uint8(r - (0xff61 - 0x21)) |
| 284 | nDst++ |
| 285 | continue |
| 286 | } |
| 287 | if atEOF && err == nil && *e != asciiState { |
| 288 | if nDst+3 > len(dst) { |
| 289 | err = transform.ErrShortDst |
| 290 | } else { |
| 291 | *e = asciiState |
| 292 | dst[nDst+0] = asciiEsc |
| 293 | dst[nDst+1] = '(' |
| 294 | dst[nDst+2] = 'B' |
| 295 | nDst += 3 |
| 296 | } |
| 297 | } |
| 298 | return nDst, nSrc, err |
| 299 | } |