gitroast/modules/mahonia/gb18030.go

157 lines
2.8 KiB
Go

package mahonia
import (
"sync"
)
// Converters for GB18030 encoding.
func init() {
RegisterCharset(&Charset{
Name: "GB18030",
NewDecoder: func() Decoder {
gb18030Once.Do(buildGB18030Tables)
return decodeGB18030Rune
},
NewEncoder: func() Encoder {
gb18030Once.Do(buildGB18030Tables)
return encodeGB18030Rune
},
})
}
func decodeGB18030Rune(p []byte) (r rune, size int, status Status) {
if len(p) == 0 {
status = NO_ROOM
return
}
b := p[0]
if b < 128 {
return rune(b), 1, SUCCESS
}
if len(p) < 2 {
status = NO_ROOM
return
}
if p[0] < 0x81 || p[0] > 0xfe {
return 0xfffd, 1, INVALID_CHAR
}
if p[1] >= 0x40 {
// 2-byte character
c := uint16(p[0])<<8 + uint16(p[1])
r = rune(gbkToUnicode[c])
if r == 0 {
r = gbkToUnicodeExtra[c]
}
if r != 0 {
return r, 2, SUCCESS
}
} else if p[1] >= 0x30 {
// 4-byte character
if len(p) < 4 {
return 0, 0, NO_ROOM
}
if p[2] < 0x81 || p[2] > 0xfe || p[3] < 0x30 || p[3] > 0x39 {
return 0xfffd, 1, INVALID_CHAR
}
code := uint32(p[0])<<24 + uint32(p[1])<<16 + uint32(p[2])<<8 + uint32(p[3])
lin := gb18030Linear(code)
if lin <= maxGB18030Linear {
r = rune(gb18030LinearToUnicode[lin])
if r != 0 {
return r, 4, SUCCESS
}
}
for _, rng := range gb18030Ranges {
if lin >= rng.firstGB && lin <= rng.lastGB {
return rng.firstRune + rune(lin) - rune(rng.firstGB), 4, SUCCESS
}
}
}
return 0xfffd, 1, INVALID_CHAR
}
func encodeGB18030Rune(p []byte, r rune) (size int, status Status) {
if len(p) == 0 {
status = NO_ROOM
return
}
if r < 128 {
p[0] = byte(r)
return 1, SUCCESS
}
if len(p) < 2 {
status = NO_ROOM
return
}
var c uint16
if r < 0x10000 {
c = unicodeToGBK[r]
} else {
c = unicodeToGBKExtra[r]
}
if c != 0 {
p[0] = byte(c >> 8)
p[1] = byte(c)
return 2, SUCCESS
}
if len(p) < 4 {
return 0, NO_ROOM
}
if r < 0x10000 {
f := unicodeToGB18030[r]
if f != 0 {
p[0] = byte(f >> 24)
p[1] = byte(f >> 16)
p[2] = byte(f >> 8)
p[3] = byte(f)
return 4, SUCCESS
}
}
for _, rng := range gb18030Ranges {
if r >= rng.firstRune && r <= rng.lastRune {
lin := rng.firstGB + uint32(r) - uint32(rng.firstRune)
p[0] = byte(lin/(10*126*10)) + 0x81
p[1] = byte(lin/(126*10)%10) + 0x30
p[2] = byte(lin/10%126) + 0x81
p[3] = byte(lin%10) + 0x30
return 4, SUCCESS
}
}
p[0] = 0x1a
return 1, INVALID_CHAR
}
var gb18030Once sync.Once
// Mapping from gb18039Linear values to Unicode.
var gb18030LinearToUnicode []uint16
var unicodeToGB18030 []uint32
func buildGB18030Tables() {
gb18030LinearToUnicode = make([]uint16, maxGB18030Linear+1)
unicodeToGB18030 = make([]uint32, 65536)
for _, data := range gb18030Data {
gb18030LinearToUnicode[gb18030Linear(data.gb18030)] = data.unicode
unicodeToGB18030[data.unicode] = data.gb18030
}
}