/* vim:set ts=2 sw=2 sts=2 et: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

/**
 * Returns `true` if given `array` contain given `element` or `false`
 * otherwise.
 * @param {Array} array
 *    Target array.
 * @param {Object|String|Number|Boolean} element
 *    Element being looked up.
 * @returns {Boolean}
 */
var has = exports.has = function has(array, element) {
  // shorter and faster equivalent of `array.indexOf(element) >= 0`
  return !!~array.indexOf(element);
};

/**
 * Adds given `element` to the given `array` if it does not contain it yet.
 * `true` is returned if element was added otherwise `false` is returned.
 * @param {Array} array
 *    Target array.
 * @param {Object|String|Number|Boolean} element
 *    Element to be added.
 * @returns {Boolean}
 */
var add = exports.add = function add(array, element) {
  var result;
  if ((result = !has(array, element)))
    array.push(element);

  return result;
};

/**
 * Removes first occurrence of the given `element` from the given `array`. If
 * `array` does not contain given `element` `false` is returned otherwise
 * `true` is returned.
 * @param {Array} array
 *    Target array.
 * @param {Object|String|Number|Boolean} element
 *    Element to be removed.
 * @returns {Boolean}
 */
exports.remove = function remove(array, element) {
  var result;
  if ((result = has(array, element)))
    array.splice(array.indexOf(element), 1);

  return result;
};

/**
 * Produces a duplicate-free version of the given `array`.
 * @param {Array} array
 *    Source array.
 * @returns {Array}
 */
exports.unique = function unique(array) {
  var value = [];
  return array.forEach(function(element) {
    add(value, element);
  });
  return value;
};