utf8 Class Reference

Public Member Functions
static function	char (local ...)
static function	codepoint (local s, local i, local j)
static function	codes (local s)
	The pattern (a string, not a function) "[\0-\x7F\xC2-\xF4][\x80-\xBF]*" (see §6.4.1), which matches exactly one UTF-8 byte sequence, assuming that the subject is a valid UTF-8 string. More...
static function	len (local s, local i, local j)
static function	offset (local s, local n, local i)

Member Function Documentation

char()

static function char

(

local ...

)

Receives zero or more integers, converts each one to its corresponding UTF-8 byte sequence and returns a string with the concatenation of all these sequences.

Returns

string

codepoint()

static function codepoint	(	local	s,
		local	i,
		local	j
	)

Returns the codepoints (as integers) from all characters in s that start between byte position i and j (both included). The default for i is 1 and for j is i. It raises an error if it meets any invalid byte sequence.

Parameters

s	string
i	number optional
j	number optional

codes()

static function codes

(

local

s

)

The pattern (a string, not a function) "[\0-\x7F\xC2-\xF4][\x80-\xBF]*" (see §6.4.1), which matches exactly one UTF-8 byte sequence, assuming that the subject is a valid UTF-8 string.

Returns values so that the construction

for p, c in utf8.codes(s) do body end

will iterate over all characters in string s, with p being the position (in bytes) and c the code point of each character. It raises an error if it meets any invalid byte sequence.

Parameters

s

string

len()

static function len	(	local	s,
		local	i,
		local	j
	)

Returns the number of UTF-8 characters in string s that start between positions i and j (both inclusive). The default for i is 1 and for j is -1. If it finds any invalid byte sequence, returns a false value plus the position of the first invalid byte.

Parameters

s	string
i	number optional
j	number optional

Returns

number

offset()

static function offset	(	local	s,
		local	n,
		local	i
	)

Returns the position (in bytes) where the encoding of the n-th character of s (counting from position i) starts. A negative n gets characters before position i. The default for i is 1 when n is non-negative and #s + 1 otherwise, so that utf8.offset(s, -n) gets the offset of the n-th character from the end of the string. If the specified character is neither in the subject nor right after its end, the function returns nil.

As a special case, when n is 0 the function returns the start of the encoding of the character that contains the i-th byte of s.

This function assumes that s is a valid UTF-8 string.

Parameters

s	string
n	number
i	number optional

Returns

number

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The documentation for this class was generated from the following file:

• lua/utf8.lua.hpp