summaryrefslogtreecommitdiff
path: root/vendor/golang.org/x/text/encoding/simplifiedchinese/hzgb2312.go
blob: eb3157f0b20efa0cf7725a9b1f531ce728357d9a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package simplifiedchinese

import (
	"unicode/utf8"

	"golang.org/x/text/encoding"
	"golang.org/x/text/encoding/internal"
	"golang.org/x/text/encoding/internal/identifier"
	"golang.org/x/text/transform"
)

// HZGB2312 is the HZ-GB2312 encoding.
var HZGB2312 encoding.Encoding = &hzGB2312

var hzGB2312 = internal.Encoding{
	internal.FuncEncoding{hzGB2312NewDecoder, hzGB2312NewEncoder},
	"HZ-GB2312",
	identifier.HZGB2312,
}

func hzGB2312NewDecoder() transform.Transformer {
	return new(hzGB2312Decoder)
}

func hzGB2312NewEncoder() transform.Transformer {
	return new(hzGB2312Encoder)
}

const (
	asciiState = iota
	gbState
)

type hzGB2312Decoder int

func (d *hzGB2312Decoder) Reset() {
	*d = asciiState
}

func (d *hzGB2312Decoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
	r, size := rune(0), 0
loop:
	for ; nSrc < len(src); nSrc += size {
		c0 := src[nSrc]
		if c0 >= utf8.RuneSelf {
			r, size = utf8.RuneError, 1
			goto write
		}

		if c0 == '~' {
			if nSrc+1 >= len(src) {
				if !atEOF {
					err = transform.ErrShortSrc
					break loop
				}
				r = utf8.RuneError
				goto write
			}
			size = 2
			switch src[nSrc+1] {
			case '{':
				*d = gbState
				continue
			case '}':
				*d = asciiState
				continue
			case '~':
				if nDst >= len(dst) {
					err = transform.ErrShortDst
					break loop
				}
				dst[nDst] = '~'
				nDst++
				continue
			case '\n':
				continue
			default:
				r = utf8.RuneError
				goto write
			}
		}

		if *d == asciiState {
			r, size = rune(c0), 1
		} else {
			if nSrc+1 >= len(src) {
				if !atEOF {
					err = transform.ErrShortSrc
					break loop
				}
				r, size = utf8.RuneError, 1
				goto write
			}
			size = 2
			c1 := src[nSrc+1]
			if c0 < 0x21 || 0x7e <= c0 || c1 < 0x21 || 0x7f <= c1 {
				// error
			} else if i := int(c0-0x01)*190 + int(c1+0x3f); i < len(decode) {
				r = rune(decode[i])
				if r != 0 {
					goto write
				}
			}
			if c1 > utf8.RuneSelf {
				// Be consistent and always treat non-ASCII as a single error.
				size = 1
			}
			r = utf8.RuneError
		}

	write:
		if nDst+utf8.RuneLen(r) > len(dst) {
			err = transform.ErrShortDst
			break loop
		}
		nDst += utf8.EncodeRune(dst[nDst:], r)
	}
	return nDst, nSrc, err
}

type hzGB2312Encoder int

func (d *hzGB2312Encoder) Reset() {
	*d = asciiState
}

func (e *hzGB2312Encoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
	r, size := rune(0), 0
	for ; nSrc < len(src); nSrc += size {
		r = rune(src[nSrc])

		// Decode a 1-byte rune.
		if r < utf8.RuneSelf {
			size = 1
			if r == '~' {
				if nDst+2 > len(dst) {
					err = transform.ErrShortDst
					break
				}
				dst[nDst+0] = '~'
				dst[nDst+1] = '~'
				nDst += 2
				continue
			} else if *e != asciiState {
				if nDst+3 > len(dst) {
					err = transform.ErrShortDst
					break
				}
				*e = asciiState
				dst[nDst+0] = '~'
				dst[nDst+1] = '}'
				nDst += 2
			} else if nDst >= len(dst) {
				err = transform.ErrShortDst
				break
			}
			dst[nDst] = uint8(r)
			nDst += 1
			continue

		}

		// Decode a multi-byte rune.
		r, size = utf8.DecodeRune(src[nSrc:])
		if size == 1 {
			// All valid runes of size 1 (those below utf8.RuneSelf) were
			// handled above. We have invalid UTF-8 or we haven't seen the
			// full character yet.
			if !atEOF && !utf8.FullRune(src[nSrc:]) {
				err = transform.ErrShortSrc
				break
			}
		}

		// func init checks that the switch covers all tables.
		switch {
		case encode0Low <= r && r < encode0High:
			if r = rune(encode0[r-encode0Low]); r != 0 {
				goto writeGB
			}
		case encode1Low <= r && r < encode1High:
			if r = rune(encode1[r-encode1Low]); r != 0 {
				goto writeGB
			}
		case encode2Low <= r && r < encode2High:
			if r = rune(encode2[r-encode2Low]); r != 0 {
				goto writeGB
			}
		case encode3Low <= r && r < encode3High:
			if r = rune(encode3[r-encode3Low]); r != 0 {
				goto writeGB
			}
		case encode4Low <= r && r < encode4High:
			if r = rune(encode4[r-encode4Low]); r != 0 {
				goto writeGB
			}
		}

	terminateInASCIIState:
		// Switch back to ASCII state in case of error so that an ASCII
		// replacement character can be written in the correct state.
		if *e != asciiState {
			if nDst+2 > len(dst) {
				err = transform.ErrShortDst
				break
			}
			dst[nDst+0] = '~'
			dst[nDst+1] = '}'
			nDst += 2
		}
		err = internal.ErrASCIIReplacement
		break

	writeGB:
		c0 := uint8(r>>8) - 0x80
		c1 := uint8(r) - 0x80
		if c0 < 0x21 || 0x7e <= c0 || c1 < 0x21 || 0x7f <= c1 {
			goto terminateInASCIIState
		}
		if *e == asciiState {
			if nDst+4 > len(dst) {
				err = transform.ErrShortDst
				break
			}
			*e = gbState
			dst[nDst+0] = '~'
			dst[nDst+1] = '{'
			nDst += 2
		} else if nDst+2 > len(dst) {
			err = transform.ErrShortDst
			break
		}
		dst[nDst+0] = c0
		dst[nDst+1] = c1
		nDst += 2
		continue
	}
	// TODO: should one always terminate in ASCII state to make it safe to
	// concatenate two HZ-GB2312-encoded strings?
	return nDst, nSrc, err
}