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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";
module.metadata = {
"stability": "unstable"
};
const { Ci, Cu } = require("chrome");
const { observe } = require("../event/chrome");
const { open } = require("../event/dom");
const { windows } = require("../window/utils");
const { filter, merge, map, expand } = require("../event/utils");
function documentMatches(weakWindow, event) {
let window = weakWindow.get();
return window && event.target === window.document;
}
function makeStrictDocumentFilter(window) {
// Note: Do not define a closure within this function. Otherwise
// you may leak the window argument.
let weak = Cu.getWeakReference(window);
return documentMatches.bind(null, weak);
}
function toEventWithDefaultViewTarget({type, target}) {
return { type: type, target: target.defaultView }
}
// Function registers single shot event listeners for relevant window events
// that forward events to exported event stream.
function eventsFor(window) {
// NOTE: Do no use pass a closure from this function into a stream
// transform function. You will capture the window in the
// closure and leak the window until the event stream is
// completely closed.
let interactive = open(window, "DOMContentLoaded", { capture: true });
let complete = open(window, "load", { capture: true });
let states = merge([interactive, complete]);
let changes = filter(states, makeStrictDocumentFilter(window));
return map(changes, toEventWithDefaultViewTarget);
}
// Create our event channels. We do this in a separate function to
// minimize the chance of leaking intermediate objects on the global.
function makeEvents() {
// In addition to observing windows that are open we also observe windows
// that are already already opened in case they're in process of loading.
var opened = windows(null, { includePrivate: true });
var currentEvents = merge(opened.map(eventsFor));
// Register system event listeners for top level window open / close.
function rename({type, target, data}) {
return { type: rename[type], target: target, data: data }
}
rename.domwindowopened = "open";
rename.domwindowclosed = "close";
var openEvents = map(observe("domwindowopened"), rename);
var closeEvents = map(observe("domwindowclosed"), rename);
var futureEvents = expand(openEvents, ({target}) => eventsFor(target));
return merge([currentEvents, futureEvents, openEvents, closeEvents]);
}
exports.events = makeEvents();
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