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// Use the fastest possible means to execute a task in a future turn
// of the event loop.
// linked list of tasks (single, with head node)
var head = {task: void 0, next: null};
var tail = head;
var flushing = false;
var requestFlush = void 0;
var isNodeJS = false;
function flush() {
/* jshint loopfunc: true */
while (head.next) {
head = head.next;
var task = head.task;
head.task = void 0;
var domain = head.domain;
if (domain) {
head.domain = void 0;
domain.enter();
}
try {
task();
} catch (e) {
if (isNodeJS) {
// In node, uncaught exceptions are considered fatal errors.
// Re-throw them synchronously to interrupt flushing!
// Ensure continuation if the uncaught exception is suppressed
// listening "uncaughtException" events (as domains does).
// Continue in next event to avoid tick recursion.
if (domain) {
domain.exit();
}
setTimeout(flush, 0);
if (domain) {
domain.enter();
}
throw e;
} else {
// In browsers, uncaught exceptions are not fatal.
// Re-throw them asynchronously to avoid slow-downs.
setTimeout(function() {
throw e;
}, 0);
}
}
if (domain) {
domain.exit();
}
}
flushing = false;
}
if (typeof process !== "undefined" && process.nextTick) {
// Node.js before 0.9. Note that some fake-Node environments, like the
// Mocha test runner, introduce a `process` global without a `nextTick`.
isNodeJS = true;
requestFlush = function () {
process.nextTick(flush);
};
} else if (typeof setImmediate === "function") {
// In IE10, Node.js 0.9+, or https://github.com/NobleJS/setImmediate
if (typeof window !== "undefined") {
requestFlush = setImmediate.bind(window, flush);
} else {
requestFlush = function () {
setImmediate(flush);
};
}
} else if (typeof MessageChannel !== "undefined") {
// modern browsers
// http://www.nonblocking.io/2011/06/windownexttick.html
var channel = new MessageChannel();
channel.port1.onmessage = flush;
requestFlush = function () {
channel.port2.postMessage(0);
};
} else {
// old browsers
requestFlush = function () {
setTimeout(flush, 0);
};
}
function asap(task) {
tail = tail.next = {
task: task,
domain: isNodeJS && process.domain,
next: null
};
if (!flushing) {
flushing = true;
requestFlush();
}
};
module.exports = asap;
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