shaka-player/lib/util/array_utils.js

/**
 * Copyright 2014 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @fileoverview Array utility functions.
 */

goog.provide('shaka.util.ArrayUtils');


/**
 * @namespace shaka.util.ArrayUtils
 * @summary Array utility functions.
 */


/**
 * Intersect two arrays.  Assumes that the arrays are already sorted.
 * @param {!Array} a
 * @param {!Array} b
 * @return {!Array} The intersection of a and b.
 * @throws {TypeError} if the array contents cannot be sorted or compared.
 */
shaka.util.ArrayUtils.intersect = function(a, b) {
  var ai = 0;
  var bi = 0;
  var result = [];
  while (ai < a.length && bi < b.length) {
    if (a[ai] < b[bi]) {
      ++ai;
    } else if (a[ai] > b[bi]) {
      ++bi;
    } else if (a[ai] == b[bi]) {
      result.push(a[ai]);
      ++ai;
      ++bi;
    } else {
      throw new TypeError('Cannot intersect non-sortable values!');
    }
  }
  return result;
};


/**
 * Create an array from object keys.
 * @param {!Object} object
 * @return {!Array} A sorted list of the keys.
 */
shaka.util.ArrayUtils.fromObjectKeys = function(object) {
  var result = [];
  for (var k in object) {
    result.push(k);
  }
  result.sort();
  return result;
};


/**
 * Remove duplicate entries from an array.
 * @param {!Array.<T>} array
 * @param {function(T): string=} opt_keyFn An optional function which takes an
 *     array item and converts it into a key.  Use this if your array items
 *     cannot be used as an index into an Object.
 * @return {!Array.<T>} A sorted list of the keys.
 * @template T
 */
shaka.util.ArrayUtils.removeDuplicates = function(array, opt_keyFn) {
  var set = {};
  for (var i = 0; i < array.length; ++i) {
    var key = opt_keyFn ? opt_keyFn(array[i]) : array[i].toString();
    set[key] = array[i];
  }

  var result = [];
  for (var k in set) {
    result.push(set[k]);
  }
  return result;
};