euckr.go 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 korean
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{EUCKR}
18
19 // EUCKR is the EUC-KR encoding, also known as Code Page 949.
20 var EUCKR encoding.Encoding = &eucKR
21
22 var eucKR = internal.Encoding{
23 Encoding: &internal.SimpleEncoding{Decoder: eucKRDecoder{}, Encoder: eucKREncoder{}},
24 Name: "EUC-KR",
25 MIB: identifier.EUCKR,
26 }
27
28 type eucKRDecoder struct{ transform.NopResetter }
29
30 func (eucKRDecoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
31 r, size := 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 break
46 }
47 c1 := src[nSrc+1]
48 size = 2
49 if c0 < 0xc7 {
50 r = 178 * rune(c0-0x81)
51 switch {
52 case 0x41 <= c1 && c1 < 0x5b:
53 r += rune(c1) - (0x41 - 0*26)
54 case 0x61 <= c1 && c1 < 0x7b:
55 r += rune(c1) - (0x61 - 1*26)
56 case 0x81 <= c1 && c1 < 0xff:
57 r += rune(c1) - (0x81 - 2*26)
58 default:
59 goto decError
60 }
61 } else if 0xa1 <= c1 && c1 < 0xff {
62 r = 178*(0xc7-0x81) + rune(c0-0xc7)*94 + rune(c1-0xa1)
63 } else {
64 goto decError
65 }
66 if int(r) < len(decode) {
67 r = rune(decode[r])
68 if r != 0 {
69 break
70 }
71 }
72 decError:
73 r = utf8.RuneError
74 if c1 < utf8.RuneSelf {
75 size = 1
76 }
77
78 default:
79 r, size = utf8.RuneError, 1
80 break
81 }
82
83 if nDst+utf8.RuneLen(r) > len(dst) {
84 err = transform.ErrShortDst
85 break
86 }
87 nDst += utf8.EncodeRune(dst[nDst:], r)
88 }
89 return nDst, nSrc, err
90 }
91
92 type eucKREncoder struct{ transform.NopResetter }
93
94 func (eucKREncoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
95 r, size := rune(0), 0
96 for ; nSrc < len(src); nSrc += size {
97 r = rune(src[nSrc])
98
99 // Decode a 1-byte rune.
100 if r < utf8.RuneSelf {
101 size = 1
102
103 if nDst >= len(dst) {
104 err = transform.ErrShortDst
105 break
106 }
107 dst[nDst] = uint8(r)
108 nDst++
109 continue
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
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 != 0 {
128 goto write2
129 }
130 case encode1Low <= r && r < encode1High:
131 if r = rune(encode1[r-encode1Low]); r != 0 {
132 goto write2
133 }
134 case encode2Low <= r && r < encode2High:
135 if r = rune(encode2[r-encode2Low]); r != 0 {
136 goto write2
137 }
138 case encode3Low <= r && r < encode3High:
139 if r = rune(encode3[r-encode3Low]); r != 0 {
140 goto write2
141 }
142 case encode4Low <= r && r < encode4High:
143 if r = rune(encode4[r-encode4Low]); r != 0 {
144 goto write2
145 }
146 case encode5Low <= r && r < encode5High:
147 if r = rune(encode5[r-encode5Low]); r != 0 {
148 goto write2
149 }
150 case encode6Low <= r && r < encode6High:
151 if r = rune(encode6[r-encode6Low]); r != 0 {
152 goto write2
153 }
154 }
155 err = internal.ErrASCIIReplacement
156 break
157 }
158
159 write2:
160 if nDst+2 > len(dst) {
161 err = transform.ErrShortDst
162 break
163 }
164 dst[nDst+0] = uint8(r >> 8)
165 dst[nDst+1] = uint8(r)
166 nDst += 2
167 continue
168 }
169 return nDst, nSrc, err
170 }
171
172 func init() {
173 // Check that the hard-coded encode switch covers all tables.
174 if numEncodeTables != 7 {
175 panic("bad numEncodeTables")
176 }
177 }
178