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|
package mahonia
import (
"unicode/utf16"
)
func init() {
for i := 0; i < len(utf16Charsets); i++ {
RegisterCharset(&utf16Charsets[i])
}
}
var utf16Charsets = []Charset{
{
Name: "UTF-16",
NewDecoder: func() Decoder {
var decodeRune Decoder
return func(p []byte) (c rune, size int, status Status) {
if decodeRune == nil {
// haven't read the BOM yet
if len(p) < 2 {
status = NO_ROOM
return
}
switch {
case p[0] == 0xfe && p[1] == 0xff:
decodeRune = decodeUTF16beRune
return 0, 2, STATE_ONLY
case p[0] == 0xff && p[1] == 0xfe:
decodeRune = decodeUTF16leRune
return 0, 2, STATE_ONLY
default:
decodeRune = decodeUTF16beRune
}
}
return decodeRune(p)
}
},
NewEncoder: func() Encoder {
wroteBOM := false
return func(p []byte, c rune) (size int, status Status) {
if !wroteBOM {
if len(p) < 2 {
status = NO_ROOM
return
}
p[0] = 0xfe
p[1] = 0xff
wroteBOM = true
return 2, STATE_ONLY
}
return encodeUTF16beRune(p, c)
}
},
},
{
Name: "UTF-16BE",
NewDecoder: func() Decoder { return decodeUTF16beRune },
NewEncoder: func() Encoder { return encodeUTF16beRune },
},
{
Name: "UTF-16LE",
NewDecoder: func() Decoder { return decodeUTF16leRune },
NewEncoder: func() Encoder { return encodeUTF16leRune },
},
}
func decodeUTF16beRune(p []byte) (r rune, size int, status Status) {
if len(p) < 2 {
status = NO_ROOM
return
}
c := rune(p[0])<<8 + rune(p[1])
if utf16.IsSurrogate(c) {
if len(p) < 4 {
status = NO_ROOM
return
}
c2 := rune(p[2])<<8 + rune(p[3])
c = utf16.DecodeRune(c, c2)
if c == 0xfffd {
return c, 2, INVALID_CHAR
} else {
return c, 4, SUCCESS
}
}
return c, 2, SUCCESS
}
func encodeUTF16beRune(p []byte, c rune) (size int, status Status) {
if c < 0x10000 {
if len(p) < 2 {
status = NO_ROOM
return
}
p[0] = byte(c >> 8)
p[1] = byte(c)
return 2, SUCCESS
}
if len(p) < 4 {
status = NO_ROOM
return
}
s1, s2 := utf16.EncodeRune(c)
p[0] = byte(s1 >> 8)
p[1] = byte(s1)
p[2] = byte(s2 >> 8)
p[3] = byte(s2)
return 4, SUCCESS
}
func decodeUTF16leRune(p []byte) (r rune, size int, status Status) {
if len(p) < 2 {
status = NO_ROOM
return
}
c := rune(p[1])<<8 + rune(p[0])
if utf16.IsSurrogate(c) {
if len(p) < 4 {
status = NO_ROOM
return
}
c2 := rune(p[3])<<8 + rune(p[2])
c = utf16.DecodeRune(c, c2)
if c == 0xfffd {
return c, 2, INVALID_CHAR
} else {
return c, 4, SUCCESS
}
}
return c, 2, SUCCESS
}
func encodeUTF16leRune(p []byte, c rune) (size int, status Status) {
if c < 0x10000 {
if len(p) < 2 {
status = NO_ROOM
return
}
p[1] = byte(c >> 8)
p[0] = byte(c)
return 2, SUCCESS
}
if len(p) < 4 {
status = NO_ROOM
return
}
s1, s2 := utf16.EncodeRune(c)
p[1] = byte(s1 >> 8)
p[0] = byte(s1)
p[3] = byte(s2 >> 8)
p[2] = byte(s2)
return 4, SUCCESS
}
|
