@a-s8h/liblevenshtein/lib/liblevenshtein/util/operations.js

Various utilities regarding Levenshtein transducers.

// Generated by CoffeeScript 1.7.1
(function() {
  var global;

  global = typeof exports === 'object' ? exports : typeof window === 'object' ? window : this;

  global['levenshtein'] || (global['levenshtein'] = {});

  global['levenshtein']['operations'] = {
    insertion: function(term, alphabet, random) {
      var c, i;
      c = alphabet[(random() * alphabet.length) >> 0];
      i = (random() * (1 + term.length)) >> 0;
      return term.slice(0, i) + c + term.slice(1 + i);
    },
    deletion: function(term, alphabet, random) {
      var i;
      i = (random() * term.length) >> 0;
      return term.slice(0, i) + term.slice(i + 1);
    },
    substitution: function(term, alphabet, random) {
      var c, i;
      c = alphabet[(random() * alphabet.length) >> 0];
      i = (random() * term.length) >> 0;
      return term.slice(0, i) + c + term.slice(i + 1);
    },
    transposition: function(term, alphabet, random) {
      var i;
      if (term.length > 1) {
        i = (random() * (term.length - 1)) >> 0;
        return term.slice(0, i) + term[i + 1] + term[i] + term.slice(i + 2);
      } else {
        return term;
      }
    },
    merge: function(term, alphabet, random) {
      var c, i;
      if (term.length > 1) {
        c = alphabet[(random() * alphabet.length) >> 0];
        i = (random() * (term.length - 1)) >> 0;
        return term.slice(0, i) + c + term.slice(i + 2);
      } else {
        return term;
      }
    },
    split: function(term, alphabet, random) {
      var c, d, i;
      c = alphabet[(random() * alphabet.length) >> 0];
      d = alphabet[(random() * alphabet.length) >> 0];
      i = (random() * (term.length - 1)) >> 0;
      return term.slice(0, i) + c + d + term.slice(i + 1);
    }
  };

}).call(this);