Should I be using Regex to uppercase uncommon characters?

Question

I've written a function for converting strings to upper case. It currently works by replacing each character using a Regex pattern with a hash:

# Special upcase function that handles several Norwegian symbols.
def norwegian_upcase(string)
 string.upcase.gsub(/[æøåäâãàáëêèéïîìíöôõòóüûùúý]/, {
 'æ' => 'Æ',
 'ø' => 'Ø',
 'å' => 'Å',
 'ä' => 'Ä',
 'â' => 'Â',
 'ã' => 'Ã',
 'à' => 'À',
 'á' => 'Á',
 'ë' => 'Ë',
 'ê' => 'Ê',
 'è' => 'È',
 'é' => 'É',
 'ï' => 'Ï',
 'î' => 'Î',
 'ì' => 'Ì',
 'í' => 'Í',
 'ö' => 'Ö',
 'ô' => 'Ô',
 'õ' => 'Õ',
 'ò' => 'Ò',
 'ó' => 'Ó',
 'ü' => 'Ü',
 'û' => 'Û',
 'ù' => 'Ù',
 'ú' => 'Ú',
 'ý' => 'Ý'
 })
end

I have the feeling that it's horribly inefficient to be using Regex like this, and that I should probably be using another method. Can anyone suggest a better way to replace single characters, or is Regex fit for the task?

• JustinC: I'd suggest looking over stackoverflow.com/questions/1020568/… which covers .downcase .upcase .capitalize and the gem unicode_utils for i8n

Answer 1

One-to-one substitution is precisely what tr is for.

def norwegian_upcase(string)
 string.upcase.tr('æ-ý','Æ-Ý')
end

That being said, the unicode_utils gem provides a method for this:

def norwegian_upcase(string)
 UnicodeUtils.upcase(string, :no)
end

I don't know Norwegian, but you can supply language subtags :nb (Norwegian Bokmal) or :nn (Norwegian Nynorsk) if they would behave differently than general :no (Norwegian).

• Hubro: I tried UnicodeUtils without success, it simply doesn't upcase æøå to ÆØÅ no matter what language i pass to it. I tried :en, :no, :nb and :nn. I haven't tried tr, but I'll check that out.

Answer 2

After a cursory glance at the character codes for these, it looks like the lowercase is 32 (decimal) higher than uppercase. e.g. 'é'.ord - 32 == 'É'.ord

You could try something like this:

string.upcase.gsub(/[æøåäâãàáëêèéïîìíöôõòóüûùúý]/){|s| (s.ord-32).chr(Encoding::UTF_8)}