49 lines
1.2 KiB
Go
49 lines
1.2 KiB
Go
// Copyright 2014 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 seq
|
|
|
|
import "unicode/utf16"
|
|
|
|
// Based heavily on package unicode/utf16 from the Go standard library.
|
|
|
|
const (
|
|
replacementChar = '\uFFFD' // Unicode replacement character
|
|
maxRune = '\U0010FFFF' // Maximum valid Unicode code point.
|
|
)
|
|
|
|
const (
|
|
// 0xd800-0xdc00 encodes the high 10 bits of a pair.
|
|
// 0xdc00-0xe000 encodes the low 10 bits of a pair.
|
|
// the value is those 20 bits plus 0x10000.
|
|
surr1 = 0xd800
|
|
surr2 = 0xdc00
|
|
surr3 = 0xe000
|
|
|
|
surrSelf = 0x10000
|
|
)
|
|
|
|
// UTF16Encode utf16 encodes s into chars. It returns the resulting
|
|
// length in units of uint16. It is assumed that the chars slice
|
|
// has enough room for the encoded string.
|
|
func UTF16Encode(s string, chars []uint16) int {
|
|
n := 0
|
|
for _, v := range s {
|
|
switch {
|
|
case v < 0, surr1 <= v && v < surr3, v > maxRune:
|
|
v = replacementChar
|
|
fallthrough
|
|
case v < surrSelf:
|
|
chars[n] = uint16(v)
|
|
n += 1
|
|
default:
|
|
// surrogate pair, two uint16 values
|
|
r1, r2 := utf16.EncodeRune(v)
|
|
chars[n] = uint16(r1)
|
|
chars[n+1] = uint16(r2)
|
|
n += 2
|
|
}
|
|
}
|
|
return n
|
|
}
|