module ActiveSupport::Multibyte::Unicode

def apply_mapping(string, mapping) #:nodoc:
  database.codepoints
  string.each_codepoint.map do |codepoint|
    cp = database.codepoints[codepoint]
    if cp and (ncp = cp.send(mapping)) and ncp > 0
      ncp
    else
      codepoint
    end
  end.pack('U*')
end