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/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
/* vim: set sts=2 sw=2 et tw=80: */
/* 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/. */
import { ExtensionUtils } from "resource://gre/modules/ExtensionUtils.sys.mjs";
const { DefaultMap } = ExtensionUtils;
/**
* Acts as a proxy for a message manager or message manager owner, and
* tracks docShell swaps so that messages are always sent to the same
* receiver, even if it is moved to a different <browser>.
*
* @param {nsIMessageSender|Element} target
* The target message manager on which to send messages, or the
* <browser> element which owns it.
*/
export class MessageManagerProxy {
constructor(target) {
this.listeners = new DefaultMap(() => new Map());
this.closed = false;
if (target instanceof Ci.nsIMessageSender) {
this.messageManager = target;
} else {
this.addListeners(target);
}
Services.obs.addObserver(this, "message-manager-close");
}
/**
* Disposes of the proxy object, removes event listeners, and drops
* all references to the underlying message manager.
*
* Must be called before the last reference to the proxy is dropped,
* unless the underlying message manager or <browser> is also being
* destroyed.
*/
dispose() {
if (this.eventTarget) {
this.removeListeners(this.eventTarget);
this.eventTarget = null;
}
this.messageManager = null;
Services.obs.removeObserver(this, "message-manager-close");
}
observe(subject, topic, data) {
if (topic === "message-manager-close") {
if (subject === this.messageManager) {
this.closed = true;
}
}
}
/**
* Returns true if the given target is the same as, or owns, the given
* message manager.
*
* @param {nsIMessageSender|MessageManagerProxy|Element} target
* The message manager, MessageManagerProxy, or <browser>
* element against which to match.
* @param {nsIMessageSender} messageManager
* The message manager against which to match `target`.
*
* @returns {boolean}
* True if `messageManager` is the same object as `target`, or
* `target` is a MessageManagerProxy or <browser> element that
* is tied to it.
*/
static matches(target, messageManager) {
return (
target === messageManager || target.messageManager === messageManager
);
}
/**
* @property {nsIMessageSender|null} messageManager
* The message manager that is currently being proxied. This
* may change during the life of the proxy object, so should
* not be stored elsewhere.
*/
/**
* Sends a message on the proxied message manager.
*
* @param {Array} args
* Arguments to be passed verbatim to the underlying
* sendAsyncMessage method.
* @returns {undefined}
*/
sendAsyncMessage(...args) {
if (this.messageManager) {
return this.messageManager.sendAsyncMessage(...args);
}
Cu.reportError(
`Cannot send message: Other side disconnected: ${uneval(args)}`
);
}
get isDisconnected() {
return this.closed || !this.messageManager;
}
/**
* Adds a message listener to the current message manager, and
* transfers it to the new message manager after a docShell swap.
*
* @param {string} message
* The name of the message to listen for.
* @param {nsIMessageListener} listener
* The listener to add.
* @param {boolean} [listenWhenClosed = false]
* If true, the listener will receive messages which were sent
* after the remote side of the listener began closing.
*/
addMessageListener(message, listener, listenWhenClosed = false) {
this.messageManager.addMessageListener(message, listener, listenWhenClosed);
this.listeners.get(message).set(listener, listenWhenClosed);
}
/**
* Adds a message listener from the current message manager.
*
* @param {string} message
* The name of the message to stop listening for.
* @param {nsIMessageListener} listener
* The listener to remove.
*/
removeMessageListener(message, listener) {
this.messageManager.removeMessageListener(message, listener);
let listeners = this.listeners.get(message);
listeners.delete(listener);
if (!listeners.size) {
this.listeners.delete(message);
}
}
/**
* Iterates over all of the currently registered message listeners.
*
* @private
*/
*iterListeners() {
for (let [message, listeners] of this.listeners) {
for (let [listener, listenWhenClosed] of listeners) {
yield { message, listener, listenWhenClosed };
}
}
}
/**
* Adds docShell swap listeners to the message manager owner.
*
* @param {Element} target
* The target element.
* @private
*/
addListeners(target) {
target.addEventListener("SwapDocShells", this);
this.eventTarget = target;
this.messageManager = target.messageManager;
for (let { message, listener, listenWhenClosed } of this.iterListeners()) {
this.messageManager.addMessageListener(
message,
listener,
listenWhenClosed
);
}
}
/**
* Removes docShell swap listeners to the message manager owner.
*
* @param {Element} target
* The target element.
* @private
*/
removeListeners(target) {
target.removeEventListener("SwapDocShells", this);
for (let { message, listener } of this.iterListeners()) {
this.messageManager.removeMessageListener(message, listener);
}
}
handleEvent(event) {
if (event.type == "SwapDocShells") {
this.removeListeners(this.eventTarget);
// The SwapDocShells event is dispatched for both browsers that are being
// swapped. To avoid double-swapping, register the event handler after
// both SwapDocShells events have fired.
this.eventTarget.addEventListener(
"EndSwapDocShells",
() => {
this.addListeners(event.detail);
},
{ once: true }
);
}
}
}
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