rss-tools/vendor/golang.org/x/text/encoding/simplifiedchinese/hzgb2312.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 | // HZGB2312 is the HZ-GB2312 encoding. |
| 17 | var HZGB2312 encoding.Encoding = &hzGB2312 |
| 18 | |
| 19 | var hzGB2312 = internal.Encoding{ |
| 20 | Encoding: internal.FuncEncoding{Decoder: hzGB2312NewDecoder, Encoder: hzGB2312NewEncoder}, |
| 21 | Name: "HZ-GB2312", |
| 22 | MIB: identifier.HZGB2312, |
| 23 | } |
| 24 | |
| 25 | func hzGB2312NewDecoder() transform.Transformer { |
| 26 | return new(hzGB2312Decoder) |
| 27 | } |
| 28 | |
| 29 | func hzGB2312NewEncoder() transform.Transformer { |
| 30 | return new(hzGB2312Encoder) |
| 31 | } |
| 32 | |
| 33 | const ( |
| 34 | asciiState = iota |
| 35 | gbState |
| 36 | ) |
| 37 | |
| 38 | type hzGB2312Decoder int |
| 39 | |
| 40 | func (d *hzGB2312Decoder) Reset() { |
| 41 | *d = asciiState |
| 42 | } |
| 43 | |
| 44 | func (d *hzGB2312Decoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) { |
| 45 | r, size := rune(0), 0 |
| 46 | loop: |
| 47 | for ; nSrc < len(src); nSrc += size { |
| 48 | c0 := src[nSrc] |
| 49 | if c0 >= utf8.RuneSelf { |
| 50 | r, size = utf8.RuneError, 1 |
| 51 | goto write |
| 52 | } |
| 53 | |
| 54 | if c0 == '~' { |
| 55 | if nSrc+1 >= len(src) { |
| 56 | if !atEOF { |
| 57 | err = transform.ErrShortSrc |
| 58 | break loop |
| 59 | } |
| 60 | r, size = utf8.RuneError, 1 |
| 61 | goto write |
| 62 | } |
| 63 | size = 2 |
| 64 | switch src[nSrc+1] { |
| 65 | case '{': |
| 66 | *d = gbState |
| 67 | continue |
| 68 | case '}': |
| 69 | *d = asciiState |
| 70 | continue |
| 71 | case '~': |
| 72 | if nDst >= len(dst) { |
| 73 | err = transform.ErrShortDst |
| 74 | break loop |
| 75 | } |
| 76 | dst[nDst] = '~' |
| 77 | nDst++ |
| 78 | continue |
| 79 | case '\n': |
| 80 | continue |
| 81 | default: |
| 82 | r = utf8.RuneError |
| 83 | goto write |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | if *d == asciiState { |
| 88 | r, size = rune(c0), 1 |
| 89 | } else { |
| 90 | if nSrc+1 >= len(src) { |
| 91 | if !atEOF { |
| 92 | err = transform.ErrShortSrc |
| 93 | break loop |
| 94 | } |
| 95 | r, size = utf8.RuneError, 1 |
| 96 | goto write |
| 97 | } |
| 98 | size = 2 |
| 99 | c1 := src[nSrc+1] |
| 100 | if c0 < 0x21 || 0x7e <= c0 || c1 < 0x21 || 0x7f <= c1 { |
| 101 | // error |
| 102 | } else if i := int(c0-0x01)*190 + int(c1+0x3f); i < len(decode) { |
| 103 | r = rune(decode[i]) |
| 104 | if r != 0 { |
| 105 | goto write |
| 106 | } |
| 107 | } |
| 108 | if c1 > utf8.RuneSelf { |
| 109 | // Be consistent and always treat non-ASCII as a single error. |
| 110 | size = 1 |
| 111 | } |
| 112 | r = utf8.RuneError |
| 113 | } |
| 114 | |
| 115 | write: |
| 116 | if nDst+utf8.RuneLen(r) > len(dst) { |
| 117 | err = transform.ErrShortDst |
| 118 | break loop |
| 119 | } |
| 120 | nDst += utf8.EncodeRune(dst[nDst:], r) |
| 121 | } |
| 122 | return nDst, nSrc, err |
| 123 | } |
| 124 | |
| 125 | type hzGB2312Encoder int |
| 126 | |
| 127 | func (d *hzGB2312Encoder) Reset() { |
| 128 | *d = asciiState |
| 129 | } |
| 130 | |
| 131 | func (e *hzGB2312Encoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) { |
| 132 | r, size := rune(0), 0 |
| 133 | for ; nSrc < len(src); nSrc += size { |
| 134 | r = rune(src[nSrc]) |
| 135 | |
| 136 | // Decode a 1-byte rune. |
| 137 | if r < utf8.RuneSelf { |
| 138 | size = 1 |
| 139 | if r == '~' { |
| 140 | if nDst+2 > len(dst) { |
| 141 | err = transform.ErrShortDst |
| 142 | break |
| 143 | } |
| 144 | dst[nDst+0] = '~' |
| 145 | dst[nDst+1] = '~' |
| 146 | nDst += 2 |
| 147 | continue |
| 148 | } else if *e != asciiState { |
| 149 | if nDst+3 > len(dst) { |
| 150 | err = transform.ErrShortDst |
| 151 | break |
| 152 | } |
| 153 | *e = asciiState |
| 154 | dst[nDst+0] = '~' |
| 155 | dst[nDst+1] = '}' |
| 156 | nDst += 2 |
| 157 | } else if nDst >= len(dst) { |
| 158 | err = transform.ErrShortDst |
| 159 | break |
| 160 | } |
| 161 | dst[nDst] = uint8(r) |
| 162 | nDst += 1 |
| 163 | continue |
| 164 | |
| 165 | } |
| 166 | |
| 167 | // Decode a multi-byte rune. |
| 168 | r, size = utf8.DecodeRune(src[nSrc:]) |
| 169 | if size == 1 { |
| 170 | // All valid runes of size 1 (those below utf8.RuneSelf) were |
| 171 | // handled above. We have invalid UTF-8 or we haven't seen the |
| 172 | // full character yet. |
| 173 | if !atEOF && !utf8.FullRune(src[nSrc:]) { |
| 174 | err = transform.ErrShortSrc |
| 175 | break |
| 176 | } |
| 177 | } |
| 178 | |
| 179 | // func init checks that the switch covers all tables. |
| 180 | switch { |
| 181 | case encode0Low <= r && r < encode0High: |
| 182 | if r = rune(encode0[r-encode0Low]); r != 0 { |
| 183 | goto writeGB |
| 184 | } |
| 185 | case encode1Low <= r && r < encode1High: |
| 186 | if r = rune(encode1[r-encode1Low]); r != 0 { |
| 187 | goto writeGB |
| 188 | } |
| 189 | case encode2Low <= r && r < encode2High: |
| 190 | if r = rune(encode2[r-encode2Low]); r != 0 { |
| 191 | goto writeGB |
| 192 | } |
| 193 | case encode3Low <= r && r < encode3High: |
| 194 | if r = rune(encode3[r-encode3Low]); r != 0 { |
| 195 | goto writeGB |
| 196 | } |
| 197 | case encode4Low <= r && r < encode4High: |
| 198 | if r = rune(encode4[r-encode4Low]); r != 0 { |
| 199 | goto writeGB |
| 200 | } |
| 201 | } |
| 202 | |
| 203 | terminateInASCIIState: |
| 204 | // Switch back to ASCII state in case of error so that an ASCII |
| 205 | // replacement character can be written in the correct state. |
| 206 | if *e != asciiState { |
| 207 | if nDst+2 > len(dst) { |
| 208 | err = transform.ErrShortDst |
| 209 | break |
| 210 | } |
| 211 | dst[nDst+0] = '~' |
| 212 | dst[nDst+1] = '}' |
| 213 | nDst += 2 |
| 214 | } |
| 215 | err = internal.ErrASCIIReplacement |
| 216 | break |
| 217 | |
| 218 | writeGB: |
| 219 | c0 := uint8(r>>8) - 0x80 |
| 220 | c1 := uint8(r) - 0x80 |
| 221 | if c0 < 0x21 || 0x7e <= c0 || c1 < 0x21 || 0x7f <= c1 { |
| 222 | goto terminateInASCIIState |
| 223 | } |
| 224 | if *e == asciiState { |
| 225 | if nDst+4 > len(dst) { |
| 226 | err = transform.ErrShortDst |
| 227 | break |
| 228 | } |
| 229 | *e = gbState |
| 230 | dst[nDst+0] = '~' |
| 231 | dst[nDst+1] = '{' |
| 232 | nDst += 2 |
| 233 | } else if nDst+2 > len(dst) { |
| 234 | err = transform.ErrShortDst |
| 235 | break |
| 236 | } |
| 237 | dst[nDst+0] = c0 |
| 238 | dst[nDst+1] = c1 |
| 239 | nDst += 2 |
| 240 | continue |
| 241 | } |
| 242 | // TODO: should one always terminate in ASCII state to make it safe to |
| 243 | // concatenate two HZ-GB2312-encoded strings? |
| 244 | return nDst, nSrc, err |
| 245 | } |