std/unicode/utf8 ​

Globals ​

const RuneError ​

The "error" rune or "Unicode replacement character"

const RuneSelf ​

Characters below RuneSelf are represented as themselves in a single byte.

const MaxRune ​

Maximum valid Unicode code point.

const UTFMax ​

Maximum number of bytes of a UTF-8 encoded Unicode character.

Functions ​

fn FullRune(p: []byte): bool

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.

fn FullRuneStr(s: str): bool

Is like FullRune but its input is a string.

fn DecodeRune(p: []byte): (r: rune, size: int)

Unpacks the first UTF-8 encoding in p and returns the rune and its width in bytes. If p is empty it returns (RuneError, 0). Otherwise, if the encoding is invalid, it returns (RuneError, 1). Both are impossible results for correct, non-empty UTF-8.

An encoding is invalid if it is incorrect UTF-8, encodes a rune that is out of range, or is not the shortest possible UTF-8 encoding for the value. No other validation is performed.

fn DecodeRuneStr(s: str): (r: rune, size: int)

Is like DecodeRune but its input is a string. If s is empty it returns (RuneError, 0). Otherwise, if the encoding is invalid, it returns (RuneError, 1). Both are impossible results for correct, non-empty UTF-8.

An encoding is invalid if it is incorrect UTF-8, encodes a rune that is out of range, or is not the shortest possible UTF-8 encoding for the value. No other validation is performed.

fn DecodeLastRune(p: []byte): (r: rune, size: int)

Unpacks the last UTF-8 encoding in p and returns the rune and its width in bytes. If p is empty it returns (RuneError, 0). Otherwise, if the encoding is invalid, it returns (RuneError, 1). Both are impossible results for correct, non-empty UTF-8.

An encoding is invalid if it is incorrect UTF-8, encodes a rune that is out of range, or is not the shortest possible UTF-8 encoding for the value. No other validation is performed.

fn DecodeLastRuneStr(s: str): (r: rune, size: int)

Is like DecodeLastRune but its input is a string. If s is empty it returns (RuneError, 0). Otherwise, if the encoding is invalid, it returns (RuneError, 1). Both are impossible results for correct, non-empty UTF-8.

An encoding is invalid if it is incorrect UTF-8, encodes a rune that is out of range, or is not the shortest possible UTF-8 encoding for the value. No other validation is performed.

fn RuneLen(r: rune): int

Returns the number of bytes required to encode the rune. It returns -1 if the rune is not a valid value to encode in UTF-8.

fn EncodeRune(mut p: []byte, mut r: rune): int

Writes into p (which must be large enough) the UTF-8 encoding of the rune. If the rune is out of range, it writes the encoding of RuneError. It returns the number of bytes written.

fn AppendRune(mut p: []byte, r: rune): []byte

Appends the UTF-8 encoding of r to the end of p and returns the extended buffer. If the rune is out of range, it appends the encoding of RuneError.

fn RuneCount(p: []byte): (n: int)

Returns the number of runes in p. Erroneous and short encodings are treated as single runes of width 1 byte.

fn RuneCountStr(s: str): (n: int)

Is like RuneCount but its input is a string.

fn RuneStart(b: byte): bool

Reports whether the byte could be the first byte of an encoded, possibly invalid rune. Second and subsequent bytes always have the top two bits set to 10.

fn Valid(p: []byte): bool

Reports whether p consists entirely of valid UTF-8-encoded runes.

fn ValidStr(mut s: str): bool

Reports whether s consists entirely of valid UTF-8-encoded runes.

fn ValidRune(r: rune): bool

Reports whether r can be legally encoded as UTF-8. Code points that are out of range or a surrogate half are illegal.