text: /*jslint node: true */
  /*global module, require*/
  'use strict';
  
  /**
   * reducePredicates reduces the predicates from an array into the grammar rules.
   * If a predicate is found to be a member of the grammar rules, it is added as a predicate.
   * @param  {Object} rules     The grammar rules.
   * @param  {String} predicate The predicate to attempt to parse.
   * @return {Object} rules     The grammar rules.
   */
  module.exports = function reducePredicates(rules, predicate) {
    if (rules.predicates.indexOf(predicate) === -1) {
      rules.predicates.push(predicate);
    }
    return rules;
  };
  