rss-tools/vendor/golang.org/x/text/encoding/japanese/shiftjis.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 | // ShiftJIS is the Shift JIS encoding, also known as Code Page 932 and |
| 17 | // Windows-31J. |
| 18 | var ShiftJIS encoding.Encoding = &shiftJIS |
| 19 | |
| 20 | var shiftJIS = internal.Encoding{ |
| 21 | Encoding: &internal.SimpleEncoding{Decoder: shiftJISDecoder{}, Encoder: shiftJISEncoder{}}, |
| 22 | Name: "Shift JIS", |
| 23 | MIB: identifier.ShiftJIS, |
| 24 | } |
| 25 | |
| 26 | type shiftJISDecoder struct{ transform.NopResetter } |
| 27 | |
| 28 | func (shiftJISDecoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) { |
| 29 | r, size := rune(0), 0 |
| 30 | loop: |
| 31 | for ; nSrc < len(src); nSrc += size { |
| 32 | switch c0 := src[nSrc]; { |
| 33 | case c0 < utf8.RuneSelf: |
| 34 | r, size = rune(c0), 1 |
| 35 | |
| 36 | case 0xa1 <= c0 && c0 < 0xe0: |
| 37 | r, size = rune(c0)+(0xff61-0xa1), 1 |
| 38 | |
| 39 | case (0x81 <= c0 && c0 < 0xa0) || (0xe0 <= c0 && c0 < 0xfd): |
| 40 | if c0 <= 0x9f { |
| 41 | c0 -= 0x70 |
| 42 | } else { |
| 43 | c0 -= 0xb0 |
| 44 | } |
| 45 | c0 = 2*c0 - 0x21 |
| 46 | |
| 47 | if nSrc+1 >= len(src) { |
| 48 | if !atEOF { |
| 49 | err = transform.ErrShortSrc |
| 50 | break loop |
| 51 | } |
| 52 | r, size = '\ufffd', 1 |
| 53 | goto write |
| 54 | } |
| 55 | c1 := src[nSrc+1] |
| 56 | switch { |
| 57 | case c1 < 0x40: |
| 58 | r, size = '\ufffd', 1 // c1 is ASCII so output on next round |
| 59 | goto write |
| 60 | case c1 < 0x7f: |
| 61 | c0-- |
| 62 | c1 -= 0x40 |
| 63 | case c1 == 0x7f: |
| 64 | r, size = '\ufffd', 1 // c1 is ASCII so output on next round |
| 65 | goto write |
| 66 | case c1 < 0x9f: |
| 67 | c0-- |
| 68 | c1 -= 0x41 |
| 69 | case c1 < 0xfd: |
| 70 | c1 -= 0x9f |
| 71 | default: |
| 72 | r, size = '\ufffd', 2 |
| 73 | goto write |
| 74 | } |
| 75 | r, size = '\ufffd', 2 |
| 76 | if i := int(c0)*94 + int(c1); i < len(jis0208Decode) { |
| 77 | r = rune(jis0208Decode[i]) |
| 78 | if r == 0 { |
| 79 | r = '\ufffd' |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | case c0 == 0x80: |
| 84 | r, size = 0x80, 1 |
| 85 | |
| 86 | default: |
| 87 | r, size = '\ufffd', 1 |
| 88 | } |
| 89 | write: |
| 90 | if nDst+utf8.RuneLen(r) > len(dst) { |
| 91 | err = transform.ErrShortDst |
| 92 | break loop |
| 93 | } |
| 94 | nDst += utf8.EncodeRune(dst[nDst:], r) |
| 95 | } |
| 96 | return nDst, nSrc, err |
| 97 | } |
| 98 | |
| 99 | type shiftJISEncoder struct{ transform.NopResetter } |
| 100 | |
| 101 | func (shiftJISEncoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) { |
| 102 | r, size := rune(0), 0 |
| 103 | loop: |
| 104 | for ; nSrc < len(src); nSrc += size { |
| 105 | r = rune(src[nSrc]) |
| 106 | |
| 107 | // Decode a 1-byte rune. |
| 108 | if r < utf8.RuneSelf { |
| 109 | size = 1 |
| 110 | |
| 111 | } else { |
| 112 | // Decode a multi-byte rune. |
| 113 | r, size = utf8.DecodeRune(src[nSrc:]) |
| 114 | if size == 1 { |
| 115 | // All valid runes of size 1 (those below utf8.RuneSelf) were |
| 116 | // handled above. We have invalid UTF-8 or we haven't seen the |
| 117 | // full character yet. |
| 118 | if !atEOF && !utf8.FullRune(src[nSrc:]) { |
| 119 | err = transform.ErrShortSrc |
| 120 | break loop |
| 121 | } |
| 122 | } |
| 123 | |
| 124 | // func init checks that the switch covers all tables. |
| 125 | switch { |
| 126 | case encode0Low <= r && r < encode0High: |
| 127 | if r = rune(encode0[r-encode0Low]); r>>tableShift == jis0208 { |
| 128 | goto write2 |
| 129 | } |
| 130 | case encode1Low <= r && r < encode1High: |
| 131 | if r = rune(encode1[r-encode1Low]); r>>tableShift == jis0208 { |
| 132 | goto write2 |
| 133 | } |
| 134 | case encode2Low <= r && r < encode2High: |
| 135 | if r = rune(encode2[r-encode2Low]); r>>tableShift == jis0208 { |
| 136 | goto write2 |
| 137 | } |
| 138 | case encode3Low <= r && r < encode3High: |
| 139 | if r = rune(encode3[r-encode3Low]); r>>tableShift == jis0208 { |
| 140 | goto write2 |
| 141 | } |
| 142 | case encode4Low <= r && r < encode4High: |
| 143 | if r = rune(encode4[r-encode4Low]); r>>tableShift == jis0208 { |
| 144 | goto write2 |
| 145 | } |
| 146 | case encode5Low <= r && r < encode5High: |
| 147 | if 0xff61 <= r && r < 0xffa0 { |
| 148 | r -= 0xff61 - 0xa1 |
| 149 | goto write1 |
| 150 | } |
| 151 | if r = rune(encode5[r-encode5Low]); r>>tableShift == jis0208 { |
| 152 | goto write2 |
| 153 | } |
| 154 | } |
| 155 | err = internal.ErrASCIIReplacement |
| 156 | break |
| 157 | } |
| 158 | |
| 159 | write1: |
| 160 | if nDst >= len(dst) { |
| 161 | err = transform.ErrShortDst |
| 162 | break |
| 163 | } |
| 164 | dst[nDst] = uint8(r) |
| 165 | nDst++ |
| 166 | continue |
| 167 | |
| 168 | write2: |
| 169 | j1 := uint8(r>>codeShift) & codeMask |
| 170 | j2 := uint8(r) & codeMask |
| 171 | if nDst+2 > len(dst) { |
| 172 | err = transform.ErrShortDst |
| 173 | break loop |
| 174 | } |
| 175 | if j1 <= 61 { |
| 176 | dst[nDst+0] = 129 + j1/2 |
| 177 | } else { |
| 178 | dst[nDst+0] = 193 + j1/2 |
| 179 | } |
| 180 | if j1&1 == 0 { |
| 181 | dst[nDst+1] = j2 + j2/63 + 64 |
| 182 | } else { |
| 183 | dst[nDst+1] = j2 + 159 |
| 184 | } |
| 185 | nDst += 2 |
| 186 | continue |
| 187 | } |
| 188 | return nDst, nSrc, err |
| 189 | } |