Source: lib/util/multi_map.js

  1. /*! @license
  2.  * Shaka Player
  3.  * Copyright 2016 Google LLC
  4.  * SPDX-License-Identifier: Apache-2.0
  5.  */
  7. goog.provide('shaka.util.MultiMap');
  10. /**
  11.  * @summary A simple multimap template.
  12.  * @template T
  13.  */
  14. shaka.util.MultiMap = class {
  15.   /** */
  16.   constructor() {
  17.     /** @private {!Object.<string, !Array.<T>>} */
  18.     this.map_ = {};
  19.   }
  22.   /**
  23.    * Add a key, value pair to the map.
  24.    * @param {string} key
  25.    * @param {T} value
  26.    */
  27.   push(key, value) {
  28.     // eslint-disable-next-line no-prototype-builtins
  29.     if (this.map_.hasOwnProperty(key)) {
  30.       this.map_[key].push(value);
  31.     } else {
  32.       this.map_[key] = [value];
  33.     }
  34.   }
  37.   /**
  38.    * Get a list of values by key.
  39.    * @param {string} key
  40.    * @return {Array.<T>} or null if no such key exists.
  41.    */
  42.   get(key) {
  43.     const list = this.map_[key];
  44.     // slice() clones the list so that it and the map can each be modified
  45.     // without affecting the other.
  46.     return list ? list.slice() : null;
  47.   }
  50.   /**
  51.    * Get a list of all values.
  52.    * @return {!Array.<T>}
  53.    */
  54.   getAll() {
  55.     const list = [];
  56.     for (const key in this.map_) {
  57.       list.push(...this.map_[key]);
  58.     }
  59.     return list;
  60.   }
  63.   /**
  64.    * Remove a specific value, if it exists.
  65.    * @param {string} key
  66.    * @param {T} value
  67.    */
  68.   remove(key, value) {
  69.     if (!(key in this.map_)) {
  70.       return;
  71.     }
  72.     this.map_[key] = this.map_[key].filter((i) => i != value);
  73.     if (this.map_[key].length == 0) {
  74.       // Delete the array if it's empty, so that |get| will reliably return null
  75.       // "if no such key exists", instead of sometimes returning an empty array.
  76.       delete this.map_[key];
  77.     }
  78.   }
  81.   /**
  82.    * Clear all keys and values from the multimap.
  83.    */
  84.   clear() {
  85.     this.map_ = {};
  86.   }
  89.   /**
  90.    * @param {function(string, !Array.<T>)} callback
  91.    */
  92.   forEach(callback) {
  93.     for (const key in this.map_) {
  94.       callback(key, this.map_[key]);
  95.     }
  96.   }
  98.   /**
  99.    * Returns the number of elements in the multimap.
  100.    * @return {number}
  101.    */
  102.   size() {
  103.     return Object.keys(this.map_).length;
  104.   }
  106.   /**
  107.    * Get a list of all the keys.
  108.    * @return {!Array.<string>}
  109.    */
  110.   keys() {
  111.     return Object.keys(this.map_);
  112.   }
  113. };