gecko-dev/browser/components/sessionstore/TabStateCache.jsm

87 lines
2.5 KiB
JavaScript

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