// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
-// UTF-8 support.
-
+// Functions and constants to support text encoded in UTF-8.
+// This package calls a Unicode character a rune for brevity.
package utf8
+// Numbers fundamental to the encoding.
const (
- RuneError = 0xFFFD;
- RuneSelf = 0x80;
- RuneMax = 0x10FFFF;
- UTFMax = 4;
+ RuneError = 0xFFFD; // the "error" Rune or "replacement character".
+ RuneSelf = 0x80; // characters below Runeself are represented as themselves in a single byte.
+ RuneMax = 0x10FFFF; // maximum Unicode code point.
+ UTFMax = 4; // maximum number of bytes of a UTF-8 encoded Unicode character.
)
const (
return RuneError, 1, false
}
+// FullRune reports whether the bytes in p begin with a full UTF-8 encoding of a rune.
+// An invalid encoding is considered a full Rune since it will convert as a width-1 error rune.
func FullRune(p []byte) bool {
rune, size, short := decodeRuneInternal(p);
return !short
}
+// FullRuneInString is like FullRune but its input is a string.
func FullRuneInString(s string, i int) bool {
rune, size, short := decodeRuneInStringInternal(s, i, len(s) - i);
return !short
}
+// DecodeRune unpacks the first UTF-8 encoding in p and returns the rune and its width in bytes.
func DecodeRune(p []byte) (rune, size int) {
var short bool;
rune, size, short = decodeRuneInternal(p);
return;
}
+// DecodeRuneInString is like DecodeRune but its input is a string.
func DecodeRuneInString(s string, i int) (rune, size int) {
var short bool;
rune, size, short = decodeRuneInStringInternal(s, i, len(s) - i);
return;
}
+// RuneLen returns the number of bytes required to encode the rune.
func RuneLen(rune int) int {
switch {
case rune <= _Rune1Max:
return -1;
}
+// EncodeRune writes into p (which must be large enough) the UTF-8 encoding of the rune.
+// It returns the number of bytes written.
func EncodeRune(rune int, p []byte) int {
if rune <= _Rune1Max {
p[0] = byte(rune);
return 4;
}
+// RuneCount returns the number of runes in p. Erroneous and short
+// encodings are treated as single runes of width 1 byte.
func RuneCount(p []byte) int {
i := 0;
var n int;
return n;
}
+// RuneCountInString is like RuneCount but its input is a string.
func RuneCountInString(s string, i int, l int) int {
ei := i + l;
n := 0;