tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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BiMap.sys.mjs (3149B)

      1 /* This Source Code Form is subject to the terms of the Mozilla Public
      2 * License, v. 2.0. If a copy of the MPL was not distributed with this
      3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      4 
      5 const lazy = {};
      6 
      7 ChromeUtils.defineESModuleGetters(lazy, {
      8  generateUUID: "chrome://remote/content/shared/UUID.sys.mjs",
      9 });
     10 
     11 /**
     12 * A bidirectional map that maintains two-way mappings between UUIDs and objects.
     13 *
     14 * This class ensures that each object maps to exactly one UUID
     15 * and vice versa. Also it allows efficient lookup in both directions:
     16 *
     17 *   - from a UUID to an object
     18 *   - from an object to a UUID
     19 */
     20 export class BiMap {
     21  #idToObject;
     22  #objectToId;
     23 
     24  constructor() {
     25    this.#idToObject = new Map();
     26    this.#objectToId = new Map();
     27  }
     28 
     29  /**
     30   * Clears all the mappings.
     31   */
     32  clear() {
     33    this.#idToObject = new Map();
     34    this.#objectToId = new Map();
     35  }
     36 
     37  /**
     38   * Deletes a mapping by the given object.
     39   *
     40   * @param {object} object
     41   *     The object to remove from the BiMap.
     42   */
     43  deleteByObject(object) {
     44    const id = this.#objectToId.get(object);
     45 
     46    if (id !== undefined) {
     47      this.#objectToId.delete(object);
     48      this.#idToObject.delete(id);
     49    }
     50  }
     51 
     52  /**
     53   * Deletes a mapping by the given id.
     54   *
     55   * @param {string} id
     56   *     The id to remove from the BiMap.
     57   */
     58  deleteById(id) {
     59    const object = this.#idToObject.get(id);
     60 
     61    if (object !== undefined) {
     62      this.#idToObject.delete(id);
     63      this.#objectToId.delete(object);
     64    }
     65  }
     66 
     67  /**
     68   * Retrieves the id for the given object, or inserts a new mapping if not found.
     69   *
     70   * @param {object} object
     71   *     The object to look up or insert.
     72   *
     73   * @returns {string}
     74   *     The id associated with the object.
     75   */
     76  getOrInsert(object) {
     77    if (this.hasObject(object)) {
     78      return this.getId(object);
     79    }
     80 
     81    const id = lazy.generateUUID();
     82    this.#objectToId.set(object, id);
     83    this.#idToObject.set(id, object);
     84 
     85    return id;
     86  }
     87 
     88  /**
     89   * Retrieves the id associated with the given object.
     90   *
     91   * @param {object} object
     92   *     The object to look up.
     93   *
     94   * @returns {string}
     95   *     The id associated with the object, or undefined if not found.
     96   */
     97  getId(object) {
     98    return this.#objectToId.get(object);
     99  }
    100 
    101  /**
    102   * Retrieves the object associated with the given id.
    103   *
    104   * @param {string} id
    105   *     The id to look up.
    106   *
    107   * @returns {object}
    108   *     The object associated with the id, or undefined if not found.
    109   */
    110  getObject(id) {
    111    return this.#idToObject.get(id);
    112  }
    113 
    114  /**
    115   * Checks whether the BiMap contains the given id.
    116   *
    117   * @param {string} id
    118   *     The id to check for.
    119   *
    120   * @returns {boolean}
    121   *     True if the id exists in the BiMap, false otherwise.
    122   */
    123  hasId(id) {
    124    return this.#idToObject.has(id);
    125  }
    126 
    127  /**
    128   * Checks whether the BiMap contains the given object.
    129   *
    130   * @param {object} object
    131   *     The object to check for.
    132   *
    133   * @returns {boolean}
    134   *     True if the object exists in the BiMap, false otherwise.
    135   */
    136  hasObject(object) {
    137    return this.#objectToId.has(object);
    138  }
    139 }