rss-tools/vendor/golang.org/x/text/encoding/traditionalchinese/big5.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 traditionalchinese |
| 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 | // All is a list of all defined encodings in this package. |
| 17 | var All = []encoding.Encoding{Big5} |
| 18 | |
| 19 | // Big5 is the Big5 encoding, also known as Code Page 950. |
| 20 | var Big5 encoding.Encoding = &big5 |
| 21 | |
| 22 | var big5 = internal.Encoding{ |
| 23 | Encoding: &internal.SimpleEncoding{Decoder: big5Decoder{}, Encoder: big5Encoder{}}, |
| 24 | Name: "Big5", |
| 25 | MIB: identifier.Big5, |
| 26 | } |
| 27 | |
| 28 | type big5Decoder struct{ transform.NopResetter } |
| 29 | |
| 30 | func (big5Decoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) { |
| 31 | r, size, s := rune(0), 0, "" |
| 32 | loop: |
| 33 | for ; nSrc < len(src); nSrc += size { |
| 34 | switch c0 := src[nSrc]; { |
| 35 | case c0 < utf8.RuneSelf: |
| 36 | r, size = rune(c0), 1 |
| 37 | |
| 38 | case 0x81 <= c0 && c0 < 0xff: |
| 39 | if nSrc+1 >= len(src) { |
| 40 | if !atEOF { |
| 41 | err = transform.ErrShortSrc |
| 42 | break loop |
| 43 | } |
| 44 | r, size = utf8.RuneError, 1 |
| 45 | goto write |
| 46 | } |
| 47 | c1 := src[nSrc+1] |
| 48 | switch { |
| 49 | case 0x40 <= c1 && c1 < 0x7f: |
| 50 | c1 -= 0x40 |
| 51 | case 0xa1 <= c1 && c1 < 0xff: |
| 52 | c1 -= 0x62 |
| 53 | case c1 < 0x40: |
| 54 | r, size = utf8.RuneError, 1 |
| 55 | goto write |
| 56 | default: |
| 57 | r, size = utf8.RuneError, 2 |
| 58 | goto write |
| 59 | } |
| 60 | r, size = '\ufffd', 2 |
| 61 | if i := int(c0-0x81)*157 + int(c1); i < len(decode) { |
| 62 | if 1133 <= i && i < 1167 { |
| 63 | // The two-rune special cases for LATIN CAPITAL / SMALL E WITH CIRCUMFLEX |
| 64 | // AND MACRON / CARON are from http://encoding.spec.whatwg.org/#big5 |
| 65 | switch i { |
| 66 | case 1133: |
| 67 | s = "\u00CA\u0304" |
| 68 | goto writeStr |
| 69 | case 1135: |
| 70 | s = "\u00CA\u030C" |
| 71 | goto writeStr |
| 72 | case 1164: |
| 73 | s = "\u00EA\u0304" |
| 74 | goto writeStr |
| 75 | case 1166: |
| 76 | s = "\u00EA\u030C" |
| 77 | goto writeStr |
| 78 | } |
| 79 | } |
| 80 | r = rune(decode[i]) |
| 81 | if r == 0 { |
| 82 | r = '\ufffd' |
| 83 | } |
| 84 | } |
| 85 | |
| 86 | default: |
| 87 | r, size = utf8.RuneError, 1 |
| 88 | } |
| 89 | |
| 90 | write: |
| 91 | if nDst+utf8.RuneLen(r) > len(dst) { |
| 92 | err = transform.ErrShortDst |
| 93 | break loop |
| 94 | } |
| 95 | nDst += utf8.EncodeRune(dst[nDst:], r) |
| 96 | continue loop |
| 97 | |
| 98 | writeStr: |
| 99 | if nDst+len(s) > len(dst) { |
| 100 | err = transform.ErrShortDst |
| 101 | break loop |
| 102 | } |
| 103 | nDst += copy(dst[nDst:], s) |
| 104 | continue loop |
| 105 | } |
| 106 | return nDst, nSrc, err |
| 107 | } |
| 108 | |
| 109 | type big5Encoder struct{ transform.NopResetter } |
| 110 | |
| 111 | func (big5Encoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) { |
| 112 | r, size := rune(0), 0 |
| 113 | for ; nSrc < len(src); nSrc += size { |
| 114 | r = rune(src[nSrc]) |
| 115 | |
| 116 | // Decode a 1-byte rune. |
| 117 | if r < utf8.RuneSelf { |
| 118 | size = 1 |
| 119 | if nDst >= len(dst) { |
| 120 | err = transform.ErrShortDst |
| 121 | break |
| 122 | } |
| 123 | dst[nDst] = uint8(r) |
| 124 | nDst++ |
| 125 | continue |
| 126 | |
| 127 | } else { |
| 128 | // Decode a multi-byte rune. |
| 129 | r, size = utf8.DecodeRune(src[nSrc:]) |
| 130 | if size == 1 { |
| 131 | // All valid runes of size 1 (those below utf8.RuneSelf) were |
| 132 | // handled above. We have invalid UTF-8 or we haven't seen the |
| 133 | // full character yet. |
| 134 | if !atEOF && !utf8.FullRune(src[nSrc:]) { |
| 135 | err = transform.ErrShortSrc |
| 136 | break |
| 137 | } |
| 138 | } |
| 139 | } |
| 140 | |
| 141 | if r >= utf8.RuneSelf { |
| 142 | // func init checks that the switch covers all tables. |
| 143 | switch { |
| 144 | case encode0Low <= r && r < encode0High: |
| 145 | if r = rune(encode0[r-encode0Low]); r != 0 { |
| 146 | goto write2 |
| 147 | } |
| 148 | case encode1Low <= r && r < encode1High: |
| 149 | if r = rune(encode1[r-encode1Low]); r != 0 { |
| 150 | goto write2 |
| 151 | } |
| 152 | case encode2Low <= r && r < encode2High: |
| 153 | if r = rune(encode2[r-encode2Low]); r != 0 { |
| 154 | goto write2 |
| 155 | } |
| 156 | case encode3Low <= r && r < encode3High: |
| 157 | if r = rune(encode3[r-encode3Low]); r != 0 { |
| 158 | goto write2 |
| 159 | } |
| 160 | case encode4Low <= r && r < encode4High: |
| 161 | if r = rune(encode4[r-encode4Low]); r != 0 { |
| 162 | goto write2 |
| 163 | } |
| 164 | case encode5Low <= r && r < encode5High: |
| 165 | if r = rune(encode5[r-encode5Low]); r != 0 { |
| 166 | goto write2 |
| 167 | } |
| 168 | case encode6Low <= r && r < encode6High: |
| 169 | if r = rune(encode6[r-encode6Low]); r != 0 { |
| 170 | goto write2 |
| 171 | } |
| 172 | case encode7Low <= r && r < encode7High: |
| 173 | if r = rune(encode7[r-encode7Low]); r != 0 { |
| 174 | goto write2 |
| 175 | } |
| 176 | } |
| 177 | err = internal.ErrASCIIReplacement |
| 178 | break |
| 179 | } |
| 180 | |
| 181 | write2: |
| 182 | if nDst+2 > len(dst) { |
| 183 | err = transform.ErrShortDst |
| 184 | break |
| 185 | } |
| 186 | dst[nDst+0] = uint8(r >> 8) |
| 187 | dst[nDst+1] = uint8(r) |
| 188 | nDst += 2 |
| 189 | continue |
| 190 | } |
| 191 | return nDst, nSrc, err |
| 192 | } |
| 193 | |
| 194 | func init() { |
| 195 | // Check that the hard-coded encode switch covers all tables. |
| 196 | if numEncodeTables != 8 { |
| 197 | panic("bad numEncodeTables") |
| 198 | } |
| 199 | } |