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/* 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);
},
/**
* Helper function used by update (see below). For message size
* optimization sometimes we don't update the whole session storage
* only the values that have been changed.
*
* @param data (object)
* The cached data where we want to update the changes.
* @param change (object)
* The actual changed values per domain.
*/
updatePartialStorageChange: function (data, change) {
if (!data.storage) {
data.storage = {};
}
let storage = data.storage;
for (let domain of Object.keys(change)) {
for (let key of Object.keys(change[domain])) {
let value = change[domain][key];
if (value === null) {
if (storage[domain] && storage[domain][key]) {
delete storage[domain][key];
}
} else {
if (!storage[domain]) {
storage[domain] = {};
}
storage[domain][key] = value;
}
}
}
},
/**
* Helper function used by update (see below). For message size
* optimization sometimes we don't update the whole browser history
* only the current index and the tail of the history from a certain
* index (specified by change.fromIdx)
*
* @param data (object)
* The cached data where we want to update the changes.
* @param change (object)
* Object containing the tail of the history array, and
* some additional metadata.
*/
updatePartialHistoryChange: function (data, change) {
const kLastIndex = Number.MAX_SAFE_INTEGER - 1;
if (!data.history) {
data.history = { entries: [] };
}
let history = data.history;
let toIdx = history.entries.length;
if ("toIdx" in change) {
toIdx = Math.min(toIdx, change.toIdx + 1);
}
for (let key of Object.keys(change)) {
if (key == "entries") {
if (change.fromIdx != kLastIndex) {
let start = change.fromIdx + 1;
history.entries.splice.apply(
history.entries, [start, toIdx - start].concat(change.entries));
}
} else if (key != "fromIdx" && key != "toIdx") {
history[key] = change[key];
}
}
},
/**
* 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)) {
if (key == "storagechange") {
this.updatePartialStorageChange(data, newData.storagechange);
continue;
}
if (key == "historychange") {
this.updatePartialHistoryChange(data, newData.historychange);
continue;
}
let value = newData[key];
if (value === null) {
delete data[key];
} else {
data[key] = value;
}
}
this._data.set(browserOrTab.permanentKey, data);
}
};
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