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

Usage#

Import this module with unicode = require 'aegisub.unicode'{:.language-lua}.

unicode.charwidth#

Synopsis: width = unicode.charwidth(instring, index=1){:.language-lua}

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.

unicode.chars#

Synopsis: for char in unicode.chars(instring) do ... end{:.language-lua}

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.

unicode.len#

Synopsis: length = unicode.len(instring){:.language-lua}

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.

unicode.codepoint#

Synopsis: val = unicode.codepoint(instring){:.language-lua}

Read the first unicode codepoint from instring.

unicode.to_upper_case#

Synopsis: upper = unicode.to_upper_case(instring){:.language-lua}

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

unicode.to_lower_case#

Synopsis: lower = unicode.to_lower_case(instring){:.language-lua}

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

unicode.to_fold_case#

Synopsis: folded = unicode.to_fold_case(instring){:.language-lua}

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

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