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

Various utilities regarding Levenshtein transducers.

// Generated by CoffeeScript 1.7.1
(function() {
  var concat, expand, global, permutations, swap,
    __slice = [].slice;

  concat = function() {
    var concatenation, list, lists, _i, _len;
    lists = 1 <= arguments.length ? __slice.call(arguments, 0) : [];
    concatenation = [];
    for (_i = 0, _len = lists.length; _i < _len; _i++) {
      list = lists[_i];
      concatenation = concatenation.concat(list);
    }
    return concatenation;
  };

  expand = function(element, lists) {
    var list, _i, _len;
    for (_i = 0, _len = lists.length; _i < _len; _i++) {
      list = lists[_i];
      list.unshift(element);
    }
    return lists;
  };

  swap = function(list, i, j) {
    var t;
    t = list[i];
    list[i] = list[j];
    list[j] = t;
    return list;
  };

  permutations = function(list, i) {
    var j, l, offset, p, _i;
    switch (list.length - i) {
      case 0:
        return [];
      case 1:
        return [[list[i]]];
      case 2:
        return [[list[i], list[i + 1]], [list[i + 1], list[i]]];
      default:
        p = [];
        offset = list.length - i;
        for (j = _i = 0; 0 <= offset ? _i < offset : _i > offset; j = 0 <= offset ? ++_i : --_i) {
          l = list.slice();
          swap(l, i, i + j);
          p.push(expand(l[i], permutations(l, i + 1)));
        }
        return concat.apply(null, p);
    }
  };

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

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

  global['levenshtein']['permutations'] = function(list) {
    return permutations(list, 0);
  };

}).call(this);