The unicode module for Automation 4 Lua contains various helper functions for working with UTF-8 encoded text.


Import this module with unicode = require 'aegisub.unicode'.


Synopsis: width = unicode.charwidth(instring, index=1)

Returns the number of bytes occupied by the UTF-8 encoded code points starting at position index in instring. The character pointed to is assumed to be a prefix byte (i.e. the first byte of the code points).

The index parameter is optional abd defaults to 1 (one) when left out, meaning the width of the first character in instring will be returned.


Synopsis: for char in unicode.chars(instring) do ... end

Returns an iterator function for looping over all code points in the given UTF-8 encoded string. For each iteration of the loop, char will contain a string representing the next code point in the string. This string may be more than one byte long.


Synopsis: length = unicode.len(instring)

Determine the length in code points of the given UTF-8 encoded string.

Be aware that this function does not run in constant time, but in linear time (O(N)) proportional to the number of Unicode code points in instring.


Synopsis: val = unicode.codepoint(instring)

Read the first unicode codepoint from instring.


Synopsis: upper = unicode.to_upper_case(instring)

Convert a string to upper case. This function handles accents, non-latin scripts, and the like.


Synopsis: lower = unicode.to_lower_case(instring)

Convert a string to lower case. This function handles accents, non-latin scripts, and the like.


Synopsis: folded = unicode.to_fold_case(instring)

Convert a string to fold case. This is similar to lower case, but is locale-insensitive and gives better results for case-insensitive comparisons.