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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 } = require("chrome");
var { emit } = require("./core");
var { when: unload } = require("../system/unload");
var listeners = new WeakMap();
const { Cu } = require("chrome");
const { ShimWaiver } = Cu.import("resource://gre/modules/ShimWaiver.jsm");
const { ThreadSafeChromeUtils } = Cu.import("resource://gre/modules/Services.jsm", {});
var getWindowFrom = x =>
x instanceof Ci.nsIDOMWindow ? x :
x instanceof Ci.nsIDOMDocument ? x.defaultView :
x instanceof Ci.nsIDOMNode ? x.ownerDocument.defaultView :
null;
function removeFromListeners() {
ShimWaiver.getProperty(this, "removeEventListener")("DOMWindowClose", removeFromListeners);
for (let cleaner of listeners.get(this))
cleaner();
listeners.delete(this);
}
// Simple utility function takes event target, event type and optional
// `options.capture` and returns node style event stream that emits "data"
// events every time event of that type occurs on the given `target`.
function open(target, type, options) {
let output = {};
let capture = options && options.capture ? true : false;
let listener = (event) => emit(output, "data", event);
// `open` is currently used only on DOM Window objects, however it was made
// to be used to any kind of `target` that supports `addEventListener`,
// therefore is safer get the `window` from the `target` instead assuming
// that `target` is the `window`.
let window = getWindowFrom(target);
// If we're not able to get a `window` from `target`, there is something
// wrong. We cannot add listeners that can leak later, or results in
// "dead object" exception.
// See: https://bugzilla.mozilla.org/show_bug.cgi?id=1001833
if (!window)
throw new Error("Unable to obtain the owner window from the target given.");
let cleaners = listeners.get(window);
if (!cleaners) {
cleaners = [];
listeners.set(window, cleaners);
// We need to remove from our map the `window` once is closed, to prevent
// memory leak
ShimWaiver.getProperty(window, "addEventListener")("DOMWindowClose", removeFromListeners);
}
cleaners.push(() => ShimWaiver.getProperty(target, "removeEventListener")(type, listener, capture));
ShimWaiver.getProperty(target, "addEventListener")(type, listener, capture);
return output;
}
unload(() => {
let keys = ThreadSafeChromeUtils.nondeterministicGetWeakMapKeys(listeners)
for (let window of keys)
removeFromListeners.call(window);
});
exports.open = open;
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