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unicode/utf8

import "unicode/utf8"

Package utf8 implements functions and constants to support text encoded in UTF-8. It includes functions to translate between runes and UTF-8 byte sequences. See https://en.wikipedia.org/wiki/UTF-8

Go 1.26.1

Constants

const (
	RuneError = '\uFFFD'     // the "error" Rune or "Unicode replacement character"
	RuneSelf  = 0x80         // characters below RuneSelf are represented as themselves in a single byte.
	MaxR...

Numbers fundamental to the encoding.

unicode/utf8/utf8.go:18

const (
	RuneError = '\uFFFD'     // the "error" Rune or "Unicode replacement character"
	RuneSelf  = 0x80         // characters below RuneSelf are represented as themselves in a single byte.
	MaxR...

Numbers fundamental to the encoding.

unicode/utf8/utf8.go:16

const (
	RuneError = '\uFFFD'     // the "error" Rune or "Unicode replacement character"
	RuneSelf  = 0x80         // characters below RuneSelf are represented as themselves in a single byte.
	MaxR...

Numbers fundamental to the encoding.

unicode/utf8/utf8.go:17

const (
	RuneError = '\uFFFD'     // the "error" Rune or "Unicode replacement character"
	RuneSelf  = 0x80         // characters below RuneSelf are represented as themselves in a single byte.
	MaxR...

Numbers fundamental to the encoding.

unicode/utf8/utf8.go:19

Functions

func AppendRune(p []byte, r rune) []byte

AppendRune 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].

unicode/utf8/utf8.go:410

func DecodeLastRune(p []byte) (rune, int)

DecodeLastRune 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.

unicode/utf8/utf8.go:279

func DecodeLastRuneInString(s string) (rune, int)

DecodeLastRuneInString 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.

unicode/utf8/utf8.go:316

func DecodeRune(p []byte) (rune, int)

DecodeRune 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.

unicode/utf8/utf8.go:157

func DecodeRuneInString(s string) (rune, int)

DecodeRuneInString 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.

unicode/utf8/utf8.go:219

func EncodeRune(p []byte, r rune) int

EncodeRune 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.

unicode/utf8/utf8.go:368

func FullRune(p []byte) bool

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.

unicode/utf8/utf8.go:110

func FullRuneInString(s string) bool

FullRuneInString is like FullRune but its input is a string.

unicode/utf8/utf8.go:130

func RuneCount(p []byte) int

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

unicode/utf8/utf8.go:434

func RuneCountInString(s string) int

RuneCountInString is like [RuneCount] but its input is a string.

unicode/utf8/utf8.go:447

func RuneLen(r rune) int

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

unicode/utf8/utf8.go:347

func RuneStart(b byte) bool

RuneStart 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.

unicode/utf8/utf8.go:457

func Valid(p []byte) bool

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

unicode/utf8/utf8.go:470

func ValidRune(r rune) bool

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

unicode/utf8/utf8.go:570

func ValidString(s string) bool

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

unicode/utf8/utf8.go:522