Replace with gsub a regexp with accents

Question

I try to get a function for setting < b > around catched strings (case insensitive), like this :

bold_string("Hello everyone","o")
> "Hell<b>o</b> every<b>o</b>ne"

bold_string("HEllo evEryonE", "e")
> "H<b>E</b>llo <b>e</b>v<b>E</b>ryon<b>E<b/>"

Now, my function looks like that :

def bold_string(str, search)
  str.gsub(/(#{search})/i, '<b>\1</b>')
end

It works perfectly with the previous examples, but not with the words having some accents. There are the results I expect :

bold_string("Petite bête", "e")
> "P<b>e</b>tit<b>e</b> b<b>ê</b>t<b>e</b>"

bold_string("Petite bête", "ê")
> "P<b>e</b>tit<b>e</b> b<b>ê</b>t<b>e</b>"

In other words, I have to find a regex like /search/i, it says "you have to find the word 'search' or the word 'search' with some accents".

edit :

I see I was too simplist with my example... It should works with string and not simply chars :

bold_string("Petite bête", "êt")
> "P<b>et</b>ite</b> b<b>êt</b>e"

Regards

Pierre

edit2 : I used the solution of FJ with this new function

def regex_from_string_including_accents(str)
  accents = ['aàâ', 'eéèêë', 'oöô' 'iî']
  return str.gsub(/./) do |letter|
    accent_group = accents.detect{|group| group.include?(letter)}
    accent_group ? "[#{accent_group}]" : letter
  end
end

Answer 1

You could do something like the following:

def bold_string(str, search)
  h = { "e" => "[eéê]", "a" => "[aáâ]" }
  regex = search.gsub(/./) {|s| h.fetch(s, s)}
  str.gsub(/(#{regex})/i, '<b>\1</b>')
end

Obviously this just shows you how to get started, you will need to fill h with additional accented versions of characters.

Example: http://ideone.com/KukiKc