UTF8 uppercase

[ivan]

I have a very simple question since I couldn't find an answer in the documentation.
How do we convert a UTF8 string into uppercase? string.upper("абв") doesn't work for Cyrillic and non-Latin scripts.
I know it can be done using 3rd party libs but is there something in the API that I'm missing?

[pgimeno]

You're not missing anything that I know. The function to convert is fairly simple though, given the appropriate table:

Code: Select all

local utf8 = require'utf8'

local toupper_table = {}

for k, v in ipairs{
  -- copy here lines 2448 to 2615 inclusive from
  -- https://github.com/starwing/luautf8/blob/e953d23/unidata.h
  -- (the file is generated from the UCD database, so it's
  -- copyright Unicode® Inc; the terms of use are here:
  -- http://www.unicode.org/terms_of_use.html
  -- but I guess starwing would appreciate being credited too
  -- as the author of the conversion program)
} do
  for j = v[1], v[2], v[3] do
    toupper_table[utf8.char(j)] = utf8.char(j + v[4])
  end
end

local function toupper(s)
  return (string.gsub(s, utf8.charpattern, toupper_table))
end

print(toupper("абв"))

Here are the links in clickable form:
https://github.com/starwing/luautf8/blo ... ta.h#L2448 - table
http://www.unicode.org/copyright.html - Unicode® Inc. terms of use. The UCD in particular has this license:
http://www.unicode.org/copyright.html#License

[ivan]

Was really hoping for something more elegant but thanks, it works!