1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/toolkit/devtools/event-emitter.js Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,192 @@
1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.6 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.7 +
1.8 +/**
1.9 + * EventEmitter.
1.10 + */
1.11 +
1.12 +this.EventEmitter = function EventEmitter() {};
1.13 +
1.14 +if (typeof(require) === "function") {
1.15 + module.exports = EventEmitter;
1.16 + var {Cu, components} = require("chrome");
1.17 +} else {
1.18 + var EXPORTED_SYMBOLS = ["EventEmitter"];
1.19 + var Cu = this["Components"].utils;
1.20 + var components = Components;
1.21 +}
1.22 +
1.23 +const { Promise: promise } = Cu.import("resource://gre/modules/Promise.jsm", {});
1.24 +const { Services } = Cu.import("resource://gre/modules/Services.jsm");
1.25 +
1.26 +/**
1.27 + * Decorate an object with event emitter functionality.
1.28 + *
1.29 + * @param Object aObjectToDecorate
1.30 + * Bind all public methods of EventEmitter to
1.31 + * the aObjectToDecorate object.
1.32 + */
1.33 +EventEmitter.decorate = function EventEmitter_decorate (aObjectToDecorate) {
1.34 + let emitter = new EventEmitter();
1.35 + aObjectToDecorate.on = emitter.on.bind(emitter);
1.36 + aObjectToDecorate.off = emitter.off.bind(emitter);
1.37 + aObjectToDecorate.once = emitter.once.bind(emitter);
1.38 + aObjectToDecorate.emit = emitter.emit.bind(emitter);
1.39 +};
1.40 +
1.41 +EventEmitter.prototype = {
1.42 + /**
1.43 + * Connect a listener.
1.44 + *
1.45 + * @param string aEvent
1.46 + * The event name to which we're connecting.
1.47 + * @param function aListener
1.48 + * Called when the event is fired.
1.49 + */
1.50 + on: function EventEmitter_on(aEvent, aListener) {
1.51 + if (!this._eventEmitterListeners)
1.52 + this._eventEmitterListeners = new Map();
1.53 + if (!this._eventEmitterListeners.has(aEvent)) {
1.54 + this._eventEmitterListeners.set(aEvent, []);
1.55 + }
1.56 + this._eventEmitterListeners.get(aEvent).push(aListener);
1.57 + },
1.58 +
1.59 + /**
1.60 + * Listen for the next time an event is fired.
1.61 + *
1.62 + * @param string aEvent
1.63 + * The event name to which we're connecting.
1.64 + * @param function aListener
1.65 + * (Optional) Called when the event is fired. Will be called at most
1.66 + * one time.
1.67 + * @return promise
1.68 + * A promise which is resolved when the event next happens. The
1.69 + * resolution value of the promise is the first event argument. If
1.70 + * you need access to second or subsequent event arguments (it's rare
1.71 + * that this is needed) then use aListener
1.72 + */
1.73 + once: function EventEmitter_once(aEvent, aListener) {
1.74 + let deferred = promise.defer();
1.75 +
1.76 + let handler = function(aEvent, aFirstArg) {
1.77 + this.off(aEvent, handler);
1.78 + if (aListener) {
1.79 + aListener.apply(null, arguments);
1.80 + }
1.81 + deferred.resolve(aFirstArg);
1.82 + }.bind(this);
1.83 +
1.84 + handler._originalListener = aListener;
1.85 + this.on(aEvent, handler);
1.86 +
1.87 + return deferred.promise;
1.88 + },
1.89 +
1.90 + /**
1.91 + * Remove a previously-registered event listener. Works for events
1.92 + * registered with either on or once.
1.93 + *
1.94 + * @param string aEvent
1.95 + * The event name whose listener we're disconnecting.
1.96 + * @param function aListener
1.97 + * The listener to remove.
1.98 + */
1.99 + off: function EventEmitter_off(aEvent, aListener) {
1.100 + if (!this._eventEmitterListeners)
1.101 + return;
1.102 + let listeners = this._eventEmitterListeners.get(aEvent);
1.103 + if (listeners) {
1.104 + this._eventEmitterListeners.set(aEvent, listeners.filter(l => {
1.105 + return l !== aListener && l._originalListener !== aListener;
1.106 + }));
1.107 + }
1.108 + },
1.109 +
1.110 + /**
1.111 + * Emit an event. All arguments to this method will
1.112 + * be sent to listner functions.
1.113 + */
1.114 + emit: function EventEmitter_emit(aEvent) {
1.115 + this.logEvent(aEvent, arguments);
1.116 +
1.117 + if (!this._eventEmitterListeners || !this._eventEmitterListeners.has(aEvent)) {
1.118 + return;
1.119 + }
1.120 +
1.121 + let originalListeners = this._eventEmitterListeners.get(aEvent);
1.122 + for (let listener of this._eventEmitterListeners.get(aEvent)) {
1.123 + // If the object was destroyed during event emission, stop
1.124 + // emitting.
1.125 + if (!this._eventEmitterListeners) {
1.126 + break;
1.127 + }
1.128 +
1.129 + // If listeners were removed during emission, make sure the
1.130 + // event handler we're going to fire wasn't removed.
1.131 + if (originalListeners === this._eventEmitterListeners.get(aEvent) ||
1.132 + this._eventEmitterListeners.get(aEvent).some(function(l) l === listener)) {
1.133 + try {
1.134 + listener.apply(null, arguments);
1.135 + }
1.136 + catch (ex) {
1.137 + // Prevent a bad listener from interfering with the others.
1.138 + let msg = ex + ": " + ex.stack;
1.139 + Cu.reportError(msg);
1.140 + dump(msg + "\n");
1.141 + }
1.142 + }
1.143 + }
1.144 + },
1.145 +
1.146 + logEvent: function(aEvent, args) {
1.147 + let logging = Services.prefs.getBoolPref("devtools.dump.emit");
1.148 +
1.149 + if (logging) {
1.150 + let caller = components.stack.caller.caller;
1.151 + let func = caller.name;
1.152 + let path = caller.filename.split(/ -> /)[1] + ":" + caller.lineNumber;
1.153 +
1.154 + let argOut = "(";
1.155 + if (args.length === 1) {
1.156 + argOut += aEvent;
1.157 + }
1.158 +
1.159 + let out = "EMITTING: ";
1.160 +
1.161 + // We need this try / catch to prevent any dead object errors.
1.162 + try {
1.163 + for (let i = 1; i < args.length; i++) {
1.164 + if (i === 1) {
1.165 + argOut = "(" + aEvent + ", ";
1.166 + } else {
1.167 + argOut += ", ";
1.168 + }
1.169 +
1.170 + let arg = args[i];
1.171 + argOut += arg;
1.172 +
1.173 + if (arg && arg.nodeName) {
1.174 + argOut += " (" + arg.nodeName;
1.175 + if (arg.id) {
1.176 + argOut += "#" + arg.id;
1.177 + }
1.178 + if (arg.className) {
1.179 + argOut += "." + arg.className;
1.180 + }
1.181 + argOut += ")";
1.182 + }
1.183 + }
1.184 + } catch(e) {
1.185 + // Object is dead so the toolbox is most likely shutting down,
1.186 + // do nothing.
1.187 + }
1.188 +
1.189 + argOut += ")";
1.190 + out += "emit" + argOut + " from " + func + "() -> " + path + "\n";
1.191 +
1.192 + dump(out);
1.193 + }
1.194 + },
1.195 +};
