michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: "use strict";
michael@0: 
michael@0: this.EXPORTED_SYMBOLS = ["TabStateCache"];
michael@0: 
michael@0: /**
michael@0:  * A cache for tabs data.
michael@0:  *
michael@0:  * This cache implements a weak map from tabs (as XUL elements)
michael@0:  * to tab data (as objects).
michael@0:  *
michael@0:  * Note that we should never cache private data, as:
michael@0:  * - that data is used very seldom by SessionStore;
michael@0:  * - caching private data in addition to public data is memory consuming.
michael@0:  */
michael@0: this.TabStateCache = Object.freeze({
michael@0:   /**
michael@0:    * Retrieves cached data for a given |browser|.
michael@0:    *
michael@0:    * @param browser (xul:browser)
michael@0:    *        The browser to retrieve cached data for.
michael@0:    * @return (object)
michael@0:    *         The cached data stored for the given |browser|.
michael@0:    */
michael@0:   get: function (browser) {
michael@0:     return TabStateCacheInternal.get(browser);
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Updates cached data for a given |browser|.
michael@0:    *
michael@0:    * @param browser (xul:browser)
michael@0:    *        The browser belonging to the given tab data.
michael@0:    * @param newData (object)
michael@0:    *        The new data to be stored for the given |browser|.
michael@0:    */
michael@0:   update: function (browser, newData) {
michael@0:     TabStateCacheInternal.update(browser, newData);
michael@0:   }
michael@0: });
michael@0: 
michael@0: let TabStateCacheInternal = {
michael@0:   _data: new WeakMap(),
michael@0: 
michael@0:   /**
michael@0:    * Retrieves cached data for a given |browser|.
michael@0:    *
michael@0:    * @param browser (xul:browser)
michael@0:    *        The browser to retrieve cached data for.
michael@0:    * @return (object)
michael@0:    *         The cached data stored for the given |browser|.
michael@0:    */
michael@0:   get: function (browser) {
michael@0:     return this._data.get(browser.permanentKey);
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Updates cached data for a given |browser|.
michael@0:    *
michael@0:    * @param browser (xul:browser)
michael@0:    *        The browser belonging to the given tab data.
michael@0:    * @param newData (object)
michael@0:    *        The new data to be stored for the given |browser|.
michael@0:    */
michael@0:   update: function (browser, newData) {
michael@0:     let data = this._data.get(browser.permanentKey) || {};
michael@0: 
michael@0:     for (let key of Object.keys(newData)) {
michael@0:       let value = newData[key];
michael@0:       if (value === null) {
michael@0:         delete data[key];
michael@0:       } else {
michael@0:         data[key] = value;
michael@0:       }
michael@0:     }
michael@0: 
michael@0:     this._data.set(browser.permanentKey, data);
michael@0:   }
michael@0: };