2019-09-21 16:11:55 +02:00

187 lines
6.3 KiB
JavaScript
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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 68
installReadyStateChangeImplementation();
} else {
// For older browsers
installSetTimeoutImplementation();
}
attachTo.setImmediate = setImmediate;
attachTo.clearImmediate = clearImmediate;
}(typeof self === "undefined" ? typeof global === "undefined" ? this : global : self));