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// 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 traditionalchinese
import (
"errors"
"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"
)
// All is a list of all defined encodings in this package.
var All = []encoding.Encoding{Big5}
// Big5 is the Big5 encoding, also known as Code Page 950.
var Big5 encoding.Encoding = &big5
var big5 = internal.Encoding{
&internal.SimpleEncoding{big5Decoder{}, big5Encoder{}},
"Big5",
identifier.Big5,
}
var errInvalidBig5 = errors.New("traditionalchinese: invalid Big5 encoding")
type big5Decoder struct{ transform.NopResetter }
func (big5Decoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
r, size, s := rune(0), 0, ""
loop:
for ; nSrc < len(src); nSrc += size {
switch c0 := src[nSrc]; {
case c0 < utf8.RuneSelf:
r, size = rune(c0), 1
case 0x81 <= c0 && c0 < 0xff:
if nSrc+1 >= len(src) {
err = transform.ErrShortSrc
break loop
}
c1 := src[nSrc+1]
switch {
case 0x40 <= c1 && c1 < 0x7f:
c1 -= 0x40
case 0xa1 <= c1 && c1 < 0xff:
c1 -= 0x62
default:
err = errInvalidBig5
break loop
}
r, size = '\ufffd', 2
if i := int(c0-0x81)*157 + int(c1); i < len(decode) {
if 1133 <= i && i < 1167 {
// The two-rune special cases for LATIN CAPITAL / SMALL E WITH CIRCUMFLEX
// AND MACRON / CARON are from http://encoding.spec.whatwg.org/#big5
switch i {
case 1133:
s = "\u00CA\u0304"
goto writeStr
case 1135:
s = "\u00CA\u030C"
goto writeStr
case 1164:
s = "\u00EA\u0304"
goto writeStr
case 1166:
s = "\u00EA\u030C"
goto writeStr
}
}
r = rune(decode[i])
if r == 0 {
r = '\ufffd'
}
}
default:
err = errInvalidBig5
break loop
}
if nDst+utf8.RuneLen(r) > len(dst) {
err = transform.ErrShortDst
break loop
}
nDst += utf8.EncodeRune(dst[nDst:], r)
continue loop
writeStr:
if nDst+len(s) > len(dst) {
err = transform.ErrShortDst
break loop
}
nDst += copy(dst[nDst:], s)
continue loop
}
if atEOF && err == transform.ErrShortSrc {
err = errInvalidBig5
}
return nDst, nSrc, err
}
type big5Encoder struct{ transform.NopResetter }
func (big5Encoder) 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 nDst >= len(dst) {
err = transform.ErrShortDst
break
}
dst[nDst] = uint8(r)
nDst++
continue
} else {
// 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
}
}
}
if r >= utf8.RuneSelf {
// func init checks that the switch covers all tables.
switch {
case encode0Low <= r && r < encode0High:
if r = rune(encode0[r-encode0Low]); r != 0 {
goto write2
}
case encode1Low <= r && r < encode1High:
if r = rune(encode1[r-encode1Low]); r != 0 {
goto write2
}
case encode2Low <= r && r < encode2High:
if r = rune(encode2[r-encode2Low]); r != 0 {
goto write2
}
case encode3Low <= r && r < encode3High:
if r = rune(encode3[r-encode3Low]); r != 0 {
goto write2
}
case encode4Low <= r && r < encode4High:
if r = rune(encode4[r-encode4Low]); r != 0 {
goto write2
}
case encode5Low <= r && r < encode5High:
if r = rune(encode5[r-encode5Low]); r != 0 {
goto write2
}
case encode6Low <= r && r < encode6High:
if r = rune(encode6[r-encode6Low]); r != 0 {
goto write2
}
case encode7Low <= r && r < encode7High:
if r = rune(encode7[r-encode7Low]); r != 0 {
goto write2
}
}
err = internal.ErrASCIIReplacement
break
}
write2:
if nDst+2 > len(dst) {
err = transform.ErrShortDst
break
}
dst[nDst+0] = uint8(r >> 8)
dst[nDst+1] = uint8(r)
nDst += 2
continue
}
return nDst, nSrc, err
}
func init() {
// Check that the hard-coded encode switch covers all tables.
if numEncodeTables != 8 {
panic("bad numEncodeTables")
}
}
|
