github.com/graybobo/golang.org-package-offline-cache@v0.0.0-20200626051047-6608995c132f/x/text/encoding/japanese/shiftjis.go (about) 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 "errors" 9 "unicode/utf8" 10 11 "golang.org/x/text/encoding" 12 "golang.org/x/text/encoding/internal" 13 "golang.org/x/text/encoding/internal/identifier" 14 "golang.org/x/text/transform" 15 ) 16 17 // ShiftJIS is the Shift JIS encoding, also known as Code Page 932 and 18 // Windows-31J. 19 var ShiftJIS encoding.Encoding = &shiftJIS 20 21 var shiftJIS = internal.Encoding{ 22 &internal.SimpleEncoding{shiftJISDecoder{}, shiftJISEncoder{}}, 23 "Shift JIS", 24 identifier.ShiftJIS, 25 } 26 27 var errInvalidShiftJIS = errors.New("japanese: invalid Shift JIS encoding") 28 29 type shiftJISDecoder struct{ transform.NopResetter } 30 31 func (shiftJISDecoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) { 32 r, size := rune(0), 0 33 loop: 34 for ; nSrc < len(src); nSrc += size { 35 switch c0 := src[nSrc]; { 36 case c0 < utf8.RuneSelf: 37 r, size = rune(c0), 1 38 39 case 0xa1 <= c0 && c0 < 0xe0: 40 r, size = rune(c0)+(0xff61-0xa1), 1 41 42 case (0x81 <= c0 && c0 < 0xa0) || (0xe0 <= c0 && c0 < 0xf0): 43 if c0 <= 0x9f { 44 c0 -= 0x70 45 } else { 46 c0 -= 0xb0 47 } 48 c0 = 2*c0 - 0x21 49 50 if nSrc+1 >= len(src) { 51 err = transform.ErrShortSrc 52 break loop 53 } 54 c1 := src[nSrc+1] 55 switch { 56 case c1 < 0x40: 57 err = errInvalidShiftJIS 58 break loop 59 case c1 < 0x7f: 60 c0-- 61 c1 -= 0x40 62 case c1 == 0x7f: 63 err = errInvalidShiftJIS 64 break loop 65 case c1 < 0x9f: 66 c0-- 67 c1 -= 0x41 68 case c1 < 0xfd: 69 c1 -= 0x9f 70 default: 71 err = errInvalidShiftJIS 72 break loop 73 } 74 r, size = '\ufffd', 2 75 if i := int(c0)*94 + int(c1); i < len(jis0208Decode) { 76 r = rune(jis0208Decode[i]) 77 if r == 0 { 78 r = '\ufffd' 79 } 80 } 81 82 default: 83 err = errInvalidShiftJIS 84 break loop 85 } 86 87 if nDst+utf8.RuneLen(r) > len(dst) { 88 err = transform.ErrShortDst 89 break loop 90 } 91 nDst += utf8.EncodeRune(dst[nDst:], r) 92 } 93 if atEOF && err == transform.ErrShortSrc { 94 err = errInvalidShiftJIS 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 }