search.js

module.exports = (function() {
  
  /* constructor */
  function Search(arr){
    if(!(this instanceof Search)) return new Search(arr);
    this._arr = arr;
    this._createTable();
  }
  
  var
  /* member */
  proto = Search.prototype = {
    _arr: null,
    _table: null,
  };
  
  /* private */
  proto._createTable = function() {
    this._table = this._arr.reduce(function(m, a, i) {
      m[a] = (m[a] || []).concat(i);
      return m;
    }, {});
  };
  
  /* public */
  proto.has = function(a) {
    return a in this._table;
  };
  
  proto.index = function(a) {
    return this._table[a] || [];
  };
  
  proto.search = function(a) {
    return this.index(a).reduce(function(m, i) {
      m.push(this._arr[i]);
      return m;
    }, []);
  };
  
  return Search;
})();