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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 japanese
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"
)
// ShiftJIS is the Shift JIS encoding, also known as Code Page 932 and
// Windows-31J.
var ShiftJIS encoding.Encoding = &shiftJIS
var shiftJIS = internal.Encoding{
&internal.SimpleEncoding{shiftJISDecoder{}, shiftJISEncoder{}},
"Shift JIS",
identifier.ShiftJIS,
}
type shiftJISDecoder struct{ transform.NopResetter }
func (shiftJISDecoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
r, size := rune(0), 0
loop:
for ; nSrc < len(src); nSrc += size {
switch c0 := src[nSrc]; {
case c0 < utf8.RuneSelf:
r, size = rune(c0), 1
case 0xa1 <= c0 && c0 < 0xe0:
r, size = rune(c0)+(0xff61-0xa1), 1
case (0x81 <= c0 && c0 < 0xa0) || (0xe0 <= c0 && c0 < 0xfd):
if c0 <= 0x9f {
c0 -= 0x70
} else {
c0 -= 0xb0
}
c0 = 2*c0 - 0x21
if nSrc+1 >= len(src) {
if !atEOF {
err = transform.ErrShortSrc
break loop
}
r, size = '\ufffd', 1
goto write
}
c1 := src[nSrc+1]
switch {
case c1 < 0x40:
r, size = '\ufffd', 1 // c1 is ASCII so output on next round
goto write
case c1 < 0x7f:
c0--
c1 -= 0x40
case c1 == 0x7f:
r, size = '\ufffd', 1 // c1 is ASCII so output on next round
goto write
case c1 < 0x9f:
c0--
c1 -= 0x41
case c1 < 0xfd:
c1 -= 0x9f
default:
r, size = '\ufffd', 2
goto write
}
r, size = '\ufffd', 2
if i := int(c0)*94 + int(c1); i < len(jis0208Decode) {
r = rune(jis0208Decode[i])
if r == 0 {
r = '\ufffd'
}
}
case c0 == 0x80:
r, size = 0x80, 1
default:
r, size = '\ufffd', 1
}
write:
if nDst+utf8.RuneLen(r) > len(dst) {
err = transform.ErrShortDst
break loop
}
nDst += utf8.EncodeRune(dst[nDst:], r)
}
return nDst, nSrc, err
}
type shiftJISEncoder struct{ transform.NopResetter }
func (shiftJISEncoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
r, size := rune(0), 0
loop:
for ; nSrc < len(src); nSrc += size {
r = rune(src[nSrc])
// Decode a 1-byte rune.
if r < utf8.RuneSelf {
size = 1
} 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 loop
}
}
// func init checks that the switch covers all tables.
switch {
case encode0Low <= r && r < encode0High:
if r = rune(encode0[r-encode0Low]); r>>tableShift == jis0208 {
goto write2
}
case encode1Low <= r && r < encode1High:
if r = rune(encode1[r-encode1Low]); r>>tableShift == jis0208 {
goto write2
}
case encode2Low <= r && r < encode2High:
if r = rune(encode2[r-encode2Low]); r>>tableShift == jis0208 {
goto write2
}
case encode3Low <= r && r < encode3High:
if r = rune(encode3[r-encode3Low]); r>>tableShift == jis0208 {
goto write2
}
case encode4Low <= r && r < encode4High:
if r = rune(encode4[r-encode4Low]); r>>tableShift == jis0208 {
goto write2
}
case encode5Low <= r && r < encode5High:
if 0xff61 <= r && r < 0xffa0 {
r -= 0xff61 - 0xa1
goto write1
}
if r = rune(encode5[r-encode5Low]); r>>tableShift == jis0208 {
goto write2
}
}
err = internal.ErrASCIIReplacement
break
}
write1:
if nDst >= len(dst) {
err = transform.ErrShortDst
break
}
dst[nDst] = uint8(r)
nDst++
continue
write2:
j1 := uint8(r>>codeShift) & codeMask
j2 := uint8(r) & codeMask
if nDst+2 > len(dst) {
err = transform.ErrShortDst
break loop
}
if j1 <= 61 {
dst[nDst+0] = 129 + j1/2
} else {
dst[nDst+0] = 193 + j1/2
}
if j1&1 == 0 {
dst[nDst+1] = j2 + j2/63 + 64
} else {
dst[nDst+1] = j2 + 159
}
nDst += 2
continue
}
return nDst, nSrc, err
}
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