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- (function (global, undefined) {
- "use strict";
- if (global.setImmediate) {
- return;
- }
- var nextHandle = 1; // Spec says greater than zero
- var tasksByHandle = {};
- var currentlyRunningATask = false;
- var doc = global.document;
- var registerImmediate;
- function setImmediate(callback) {
- // Callback can either be a function or a string
- if (typeof callback !== "function") {
- callback = new Function("" + callback);
- }
- // Copy function arguments
- var args = new Array(arguments.length - 1);
- for (var i = 0; i < args.length; i++) {
- args[i] = arguments[i + 1];
- }
- // Store and register the task
- var task = { callback: callback, args: args };
- tasksByHandle[nextHandle] = task;
- registerImmediate(nextHandle);
- return nextHandle++;
- }
- function clearImmediate(handle) {
- delete tasksByHandle[handle];
- }
- function run(task) {
- var callback = task.callback;
- var args = task.args;
- switch (args.length) {
- case 0:
- callback();
- break;
- case 1:
- callback(args[0]);
- break;
- case 2:
- callback(args[0], args[1]);
- break;
- case 3:
- callback(args[0], args[1], args[2]);
- break;
- default:
- callback.apply(undefined, args);
- break;
- }
- }
- function runIfPresent(handle) {
- // From the spec: "Wait until any invocations of this algorithm started before this one have completed."
- // So if we're currently running a task, we'll need to delay this invocation.
- if (currentlyRunningATask) {
- // Delay by doing a setTimeout. setImmediate was tried instead, but in Firefox 7 it generated a
- // "too much recursion" error.
- setTimeout(runIfPresent, 0, handle);
- } else {
- var task = tasksByHandle[handle];
- if (task) {
- currentlyRunningATask = true;
- try {
- run(task);
- } finally {
- clearImmediate(handle);
- currentlyRunningATask = false;
- }
- }
- }
- }
- function installNextTickImplementation() {
- registerImmediate = function(handle) {
- process.nextTick(function () { runIfPresent(handle); });
- };
- }
- function canUsePostMessage() {
- // The test against `importScripts` prevents this implementation from being installed inside a web worker,
- // where `global.postMessage` means something completely different and can't be used for this purpose.
- if (global.postMessage && !global.importScripts) {
- var postMessageIsAsynchronous = true;
- var oldOnMessage = global.onmessage;
- global.onmessage = function() {
- postMessageIsAsynchronous = false;
- };
- global.postMessage("", "*");
- global.onmessage = oldOnMessage;
- return postMessageIsAsynchronous;
- }
- }
- function installPostMessageImplementation() {
- // Installs an event handler on `global` for the `message` event: see
- // * https://developer.mozilla.org/en/DOM/window.postMessage
- // * http://www.whatwg.org/specs/web-apps/current-work/multipage/comms.html#crossDocumentMessages
- var messagePrefix = "setImmediate$" + Math.random() + "$";
- var onGlobalMessage = function(event) {
- if (event.source === global &&
- typeof event.data === "string" &&
- event.data.indexOf(messagePrefix) === 0) {
- runIfPresent(+event.data.slice(messagePrefix.length));
- }
- };
- if (global.addEventListener) {
- global.addEventListener("message", onGlobalMessage, false);
- } else {
- global.attachEvent("onmessage", onGlobalMessage);
- }
- registerImmediate = function(handle) {
- global.postMessage(messagePrefix + handle, "*");
- };
- }
- function installMessageChannelImplementation() {
- var channel = new MessageChannel();
- channel.port1.onmessage = function(event) {
- var handle = event.data;
- runIfPresent(handle);
- };
- registerImmediate = function(handle) {
- channel.port2.postMessage(handle);
- };
- }
- function installReadyStateChangeImplementation() {
- var html = doc.documentElement;
- registerImmediate = function(handle) {
- // Create a <script> element; its readystatechange event will be fired asynchronously once it is inserted
- // into the document. Do so, thus queuing up the task. Remember to clean up once it's been called.
- var script = doc.createElement("script");
- script.onreadystatechange = function () {
- runIfPresent(handle);
- script.onreadystatechange = null;
- html.removeChild(script);
- script = null;
- };
- html.appendChild(script);
- };
- }
- function installSetTimeoutImplementation() {
- registerImmediate = function(handle) {
- setTimeout(runIfPresent, 0, handle);
- };
- }
- // If supported, we should attach to the prototype of global, since that is where setTimeout et al. live.
- var attachTo = Object.getPrototypeOf && Object.getPrototypeOf(global);
- attachTo = attachTo && attachTo.setTimeout ? attachTo : global;
- // Don't get fooled by e.g. browserify environments.
- if ({}.toString.call(global.process) === "[object process]") {
- // For Node.js before 0.9
- installNextTickImplementation();
- } else if (canUsePostMessage()) {
- // For non-IE10 modern browsers
- installPostMessageImplementation();
- } else if (global.MessageChannel) {
- // For web workers, where supported
- installMessageChannelImplementation();
- } else if (doc && "onreadystatechange" in doc.createElement("script")) {
- // For IE 6–8
- installReadyStateChangeImplementation();
- } else {
- // For older browsers
- installSetTimeoutImplementation();
- }
- attachTo.setImmediate = setImmediate;
- attachTo.clearImmediate = clearImmediate;
- }(typeof self === "undefined" ? typeof global === "undefined" ? this : global : self));
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