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 {!Map<string, !Array<T>>} */
  18.     this.map_ = new 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.     if (this.map_.has(key)) {
  29.       this.map_.get(key).push(value);
  30.     } else {
  31.       this.map_.set(key, [value]);
  32.     }
  33.   }
  36.   /**
  37.    * Get a list of values by key.
  38.    * @param {string} key
  39.    * @return {Array<T>} or null if no such key exists.
  40.    */
  41.   get(key) {
  42.     if (!this.map_.has(key)) {
  43.       return null;
  44.     }
  45.     // slice() clones the list so that it and the map can each be modified
  46.     // without affecting the other.
  47.     return this.map_.get(key).slice();
  48.   }
  51.   /**
  52.    * Get a list of all values.
  53.    * @return {!Array<T>}
  54.    */
  55.   getAll() {
  56.     const list = [];
  57.     for (const value of this.map_.values()) {
  58.       list.push(...value);
  59.     }
  60.     return list;
  61.   }
  64.   /**
  65.    * Remove a specific value, if it exists.
  66.    * @param {string} key
  67.    * @param {T} value
  68.    */
  69.   remove(key, value) {
  70.     if (!this.map_.has(key)) {
  71.       return;
  72.     }
  73.     const newValue = this.map_.get(key).filter((i) => i != value);
  74.     this.map_.set(key, newValue);
  75.     if (!newValue.length) {
  76.       // Delete the array if it's empty, so that |get| will reliably return null
  77.       // "if no such key exists", instead of sometimes returning an empty array.
  78.       this.map_.delete(key);
  79.     }
  80.   }
  83.   /**
  84.    * Clear all keys and values from the multimap.
  85.    */
  86.   clear() {
  87.     this.map_.clear();
  88.   }
  91.   /**
  92.    * @param {function(string, !Array<T>)} callback
  93.    */
  94.   forEach(callback) {
  95.     this.map_.forEach((value, key) => {
  96.       callback(key, value);
  97.     });
  98.   }
  100.   /**
  101.    * Returns the number of elements in the multimap.
  102.    * @return {number}
  103.    */
  104.   size() {
  105.     return this.map_.size;
  106.   }
  108.   /**
  109.    * Get a list of all the keys.
  110.    * @return {!Array<string>}
  111.    */
  112.   keys() {
  113.     return Array.from(this.map_.keys());
  114.   }
  115. };