levenshtein_distance

# File railties/lib/rails/command/behavior.rb, line 27
          def levenshtein_distance(str1, str2) # :doc:
            s = str1
            t = str2
            n = s.length
            m = t.length

            return m if (0 == n)
            return n if (0 == m)

            d = (0..m).to_a
            x = nil

            # avoid duplicating an enumerable object in the loop
            str2_codepoint_enumerable = str2.each_codepoint

            str1.each_codepoint.with_index do |char1, i|
              e = i + 1

              str2_codepoint_enumerable.with_index do |char2, j|
                cost = (char1 == char2) ? 0 : 1
                x = [
                     d[j + 1] + 1, # insertion
                     e + 1,      # deletion
                     d[j] + cost # substitution
                    ].min
                d[j] = e
                e = x
              end

              d[m] = x
            end

            x
          end