89 lines
1.3 KiB
Go
89 lines
1.3 KiB
Go
package mahonia
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// Converters for Big 5 encoding.
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import (
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"sync"
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)
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func init() {
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RegisterCharset(&Charset{
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Name: "Big5",
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Aliases: []string{"csBig5"},
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NewDecoder: func() Decoder {
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return decodeBig5Rune
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},
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NewEncoder: func() Encoder {
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big5Once.Do(reverseBig5Table)
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return encodeBig5Rune
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},
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})
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}
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func decodeBig5Rune(p []byte) (r rune, size int, status Status) {
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if len(p) == 0 {
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status = NO_ROOM
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return
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}
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b := p[0]
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if b < 128 {
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return rune(b), 1, SUCCESS
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}
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if len(p) < 2 {
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status = NO_ROOM
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return
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}
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c := int(p[0])<<8 + int(p[1])
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c = int(big5ToUnicode[c])
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if c > 0 {
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return rune(c), 2, SUCCESS
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}
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return 0xfffd, 1, INVALID_CHAR
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}
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func encodeBig5Rune(p []byte, r rune) (size int, status Status) {
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if len(p) == 0 {
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status = NO_ROOM
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return
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}
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if r < 128 {
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p[0] = byte(r)
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return 1, SUCCESS
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}
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if len(p) < 2 {
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status = NO_ROOM
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return
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}
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if r < 0x10000 {
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c := unicodeToBig5[r]
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if c > 0 {
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p[0] = byte(c >> 8)
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p[1] = byte(c)
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return 2, SUCCESS
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}
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}
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p[0] = '?'
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return 1, INVALID_CHAR
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}
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var big5Once sync.Once
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var unicodeToBig5 []uint16
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func reverseBig5Table() {
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unicodeToBig5 = make([]uint16, 65536)
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for big5, unicode := range big5ToUnicode {
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if unicode > 0 {
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unicodeToBig5[unicode] = uint16(big5)
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}
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}
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}
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