@a-s8h/liblevenshtein/lib/liblevenshtein/collection/dawg.js

Various utilities regarding Levenshtein transducers.

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

  DawgNode = (function() {
    DawgNode.next_id = 0;

    function DawgNode() {
      this.id = DawgNode.next_id;
      DawgNode.next_id += 1;
      this['is_final'] = false;
      this['edges'] = {};
    }

    DawgNode.prototype.bisect_left = function(edges, edge, lower, upper) {
      var i;
      while (lower < upper) {
        i = (lower + upper) >> 1;
        if (edges[i] < edge) {
          lower = i + 1;
        } else {
          upper = i;
        }
      }
      return lower;
    };

    DawgNode.prototype['toString'] = function() {
      var edge, edges, label, node, _ref;
      edges = [];
      _ref = this['edges'];
      for (label in _ref) {
        node = _ref[label];
        edge = label + node.id.toString();
        edges.splice(this.bisect_left(edges, edge, 0, edges.length), 0, edge);
      }
      return (+this['is_final']) + edges.join('');
    };

    return DawgNode;

  })();

  Dawg = (function() {
    function Dawg(dictionary) {
      var word, _i, _len;
      if (!(dictionary && typeof dictionary.length === 'number')) {
        throw new Error("Expected dictionary to be array-like");
      }
      this.previous_word = '';
      this['root'] = new DawgNode();
      this.unchecked_nodes = [];
      this.minimized_nodes = {};
      for (_i = 0, _len = dictionary.length; _i < _len; _i++) {
        word = dictionary[_i];
        this['insert'](word);
      }
      this.finish();
    }

    Dawg.prototype['insert'] = function(word) {
      var character, i, next_node, node, previous_word, unchecked_nodes, upper_bound;
      i = 0;
      previous_word = this.previous_word;
      upper_bound = word.length < previous_word.length ? word.length : previous_word.length;
      while (i < upper_bound && word[i] === previous_word[i]) {
        i += 1;
      }
      this.minimize(i);
      unchecked_nodes = this.unchecked_nodes;
      if (unchecked_nodes.length === 0) {
        node = this['root'];
      } else {
        node = unchecked_nodes[unchecked_nodes.length - 1][2];
      }
      while ((character = word[i]) !== undefined) {
        next_node = new DawgNode();
        node['edges'][character] = next_node;
        unchecked_nodes.push([node, character, next_node]);
        node = next_node;
        i += 1;
      }
      node['is_final'] = true;
      this.previous_word = word;
    };

    Dawg.prototype.finish = function() {
      this.minimize(0);
    };

    Dawg.prototype.minimize = function(lower_bound) {
      var character, child, child_key, j, minimized_nodes, parent, unchecked_nodes, _ref;
      minimized_nodes = this.minimized_nodes;
      unchecked_nodes = this.unchecked_nodes;
      j = unchecked_nodes.length;
      while (j > lower_bound) {
        _ref = unchecked_nodes.pop(), parent = _ref[0], character = _ref[1], child = _ref[2];
        child_key = child.toString();
        if (child_key in minimized_nodes) {
          parent['edges'][character] = minimized_nodes[child_key];
        } else {
          minimized_nodes[child_key] = child;
        }
        j -= 1;
      }
    };

    Dawg.prototype['accepts'] = function(word) {
      var edge, node, _i, _len;
      node = this['root'];
      for (_i = 0, _len = word.length; _i < _len; _i++) {
        edge = word[_i];
        node = node['edges'][edge];
        if (!node) {
          return false;
        }
      }
      return node['is_final'];
    };

    return Dawg;

  })();

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

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

  global['levenshtein']['DawgNode'] = DawgNode;

  global['levenshtein']['Dawg'] = Dawg;

}).call(this);