class Levenshtein

# File lib/levenshteinish.rb, line 5
def self.distance(s1, s2, threshold = nil)
  
  # If the arguments is nil
  s1 = s1.to_s unless s1
  s2 = s2.to_s unless s2
  
  s1, s2  = s2, s1  if s1.length > s2.length  # s1 is the short one; s2 is the long one.

  if s2.length == 0
    0.0 # Since s1.length < s2.length, s1 must be empty as well.
  else
    if threshold
      if (d = HintableLevenshtein.new.distance(s1, s2).to_f/s2.length) <= threshold
        d
      else
        nil
      end
    else
      HintableLevenshtein.new.distance(s1, s2).to_f/s2.length
    end
  end
end