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89 lines
1.5 KiB
Go
89 lines
1.5 KiB
Go
package charset
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import (
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"fmt"
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"unicode/utf8"
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)
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func init() {
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registerClass("big5", fromBig5, nil)
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}
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// Big5 consists of 89 fonts of 157 chars each
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const (
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big5Max = 13973
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big5Font = 157
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big5Data = "big5.dat"
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)
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type translateFromBig5 struct {
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font int
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scratch []byte
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big5map []rune
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}
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func (p *translateFromBig5) Translate(data []byte, eof bool) (int, []byte, error) {
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p.scratch = p.scratch[:0]
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n := 0
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for len(data) > 0 {
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c := int(data[0])
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data = data[1:]
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n++
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if p.font == -1 {
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// idle state
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if c >= 0xa1 {
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p.font = c
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continue
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}
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if c == 26 {
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c = '\n'
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}
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continue
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}
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f := p.font
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p.font = -1
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r := utf8.RuneError
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switch {
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case c >= 64 && c <= 126:
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c -= 64
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case c >= 161 && c <= 254:
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c = c - 161 + 63
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default:
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// bad big5 char
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f = 255
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}
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if f <= 254 {
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f -= 161
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ix := f*big5Font + c
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if ix < len(p.big5map) {
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r = p.big5map[ix]
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}
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if r == -1 {
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r = utf8.RuneError
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}
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}
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p.scratch = appendRune(p.scratch, r)
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}
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return n, p.scratch, nil
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}
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type big5Key bool
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func fromBig5(arg string) (Translator, error) {
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big5map, err := cache(big5Key(false), func() (interface{}, error) {
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data, err := readFile(big5Data)
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if err != nil {
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return nil, fmt.Errorf("charset: cannot open big5 data file: %v", err)
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}
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big5map := []rune(string(data))
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if len(big5map) != big5Max {
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return nil, fmt.Errorf("charset: corrupt big5 data")
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}
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return big5map, nil
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})
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if err != nil {
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return nil, err
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}
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return &translateFromBig5{big5map: big5map.([]rune), font: -1}, nil
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}
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