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share/www/static/q.js  view on Meta::CPAN

        var tail = head;
        var maxPendingTicks = 2;
        var pendingTicks = 0;
        var queuedTasks = 0;
        var usedTicks = 0;
        var requestTick = void 0;

        function onTick() {
            // In case of multiple tasks ensure at least one subsequent tick
            // to handle remaining tasks in case one throws.
            --pendingTicks;

            if (++usedTicks >= maxPendingTicks) {
                // Amortize latency after thrown exceptions.
                usedTicks = 0;
                maxPendingTicks *= 4; // fast grow!
                var expectedTicks = queuedTasks && Math.min(
                    queuedTasks - 1,
                    maxPendingTicks
                );
                while (pendingTicks < expectedTicks) {
                    ++pendingTicks;
                    requestTick();
                }
            }

            while (queuedTasks) {
                --queuedTasks; // decrement here to ensure it's never negative
                head = head.next;
                var task = head.task;
                head.task = void 0;
                task();
            }

            usedTicks = 0;
        }

        nextTick = function (task) {
            tail = tail.next = {task: task, next: null};
            if (
                pendingTicks < ++queuedTasks &&
                pendingTicks < maxPendingTicks
            ) {
                ++pendingTicks;
                requestTick();
            }
        };

        if (typeof MessageChannel !== "undefined") {
            // modern browsers
            // http://www.nonblocking.io/2011/06/windownexttick.html
            var channel = new MessageChannel();
            channel.port1.onmessage = onTick;
            requestTick = function () {
                channel.port2.postMessage(0);
            };

        } else {
            // old browsers
            requestTick = function () {
                setTimeout(onTick, 0);
            };
        }
    })();
}

// Attempt to make generics safe in the face of downstream
// modifications.
// There is no situation where this is necessary.
// If you need a security guarantee, these primordials need to be
// deeply frozen anyway, and if you don’t need a security guarantee,
// this is just plain paranoid.
// However, this does have the nice side-effect of reducing the size
// of the code by reducing x.call() to merely x(), eliminating many
// hard-to-minify characters.
// See Mark Miller’s explanation of what this does.
// http://wiki.ecmascript.org/doku.php?id=conventions:safe_meta_programming
function uncurryThis(f) {
    var call = Function.call;
    return function () {
        return call.apply(f, arguments);
    };
}
// This is equivalent, but slower:
// uncurryThis = Function_bind.bind(Function_bind.call);
// http://jsperf.com/uncurrythis

var array_slice = uncurryThis(Array.prototype.slice);

var array_reduce = uncurryThis(
    Array.prototype.reduce || function (callback, basis) {
        var index = 0,
            length = this.length;
        // concerning the initial value, if one is not provided
        if (arguments.length === 1) {
            // seek to the first value in the array, accounting
            // for the possibility that is is a sparse array
            do {
                if (index in this) {
                    basis = this[index++];
                    break;
                }
                if (++index >= length) {
                    throw new TypeError();
                }
            } while (1);
        }
        // reduce
        for (; index < length; index++) {
            // account for the possibility that the array is sparse
            if (index in this) {
                basis = callback(basis, this[index], index);
            }
        }
        return basis;
    }
);

var array_indexOf = uncurryThis(
    Array.prototype.indexOf || function (value) {
        // not a very good shim, but good enough for our one use of it

share/www/static/q.js  view on Meta::CPAN

 */
Q["finally"] = // XXX experimental
Q.fin = fin;
function fin(promise, callback) {
    return when(promise, function (value) {
        return when(callback(), function () {
            return value;
        });
    }, function (exception) {
        return when(callback(), function () {
            return reject(exception);
        });
    });
}

/**
 * Terminates a chain of promises, forcing rejections to be
 * thrown as exceptions.
 * @param {Any*} promise at the end of a chain of promises
 * @returns nothing
 */
Q.done = done;
function done(promise, fulfilled, rejected, progress) {
    var onUnhandledError = function (error) {
        // forward to a future turn so that ``when``
        // does not catch it and turn it into a rejection.
        nextTick(function () {
            makeStackTraceLong(error, promise);

            if (Q.onerror) {
                Q.onerror(error);
            } else {
                throw error;
            }
        });
    };

    // Avoid unnecessary `nextTick`ing via an unnecessary `when`.
    var promiseToHandle = fulfilled || rejected || progress ?
        when(promise, fulfilled, rejected, progress) :
        promise;

    if (typeof process === "object" && process && process.domain) {
        onUnhandledError = process.domain.bind(onUnhandledError);
    }
    fail(promiseToHandle, onUnhandledError);
}

/**
 * Causes a promise to be rejected if it does not get fulfilled before
 * some milliseconds time out.
 * @param {Any*} promise
 * @param {Number} milliseconds timeout
 * @param {String} custom error message (optional)
 * @returns a promise for the resolution of the given promise if it is
 * fulfilled before the timeout, otherwise rejected.
 */
Q.timeout = timeout;
function timeout(promise, ms, msg) {
    var deferred = defer();
    var timeoutId = setTimeout(function () {
        deferred.reject(new Error(msg || "Timed out after " + ms + " ms"));
    }, ms);

    when(promise, function (value) {
        clearTimeout(timeoutId);
        deferred.resolve(value);
    }, function (exception) {
        clearTimeout(timeoutId);
        deferred.reject(exception);
    }, deferred.notify);

    return deferred.promise;
}

/**
 * Returns a promise for the given value (or promised value) after some
 * milliseconds.
 * @param {Any*} promise
 * @param {Number} milliseconds
 * @returns a promise for the resolution of the given promise after some
 * time has elapsed.
 */
Q.delay = delay;
function delay(promise, timeout) {
    if (timeout === void 0) {
        timeout = promise;
        promise = void 0;
    }

    var deferred = defer();

    when(promise, undefined, undefined, deferred.notify);
    setTimeout(function () {
        deferred.resolve(promise);
    }, timeout);

    return deferred.promise;
}

/**
 * Passes a continuation to a Node function, which is called with the given
 * arguments provided as an array, and returns a promise.
 *
 *      Q.nfapply(FS.readFile, [__filename])
 *      .then(function (content) {
 *      })
 *
 */
Q.nfapply = nfapply;
function nfapply(callback, args) {
    var nodeArgs = array_slice(args);
    var deferred = defer();
    nodeArgs.push(deferred.makeNodeResolver());

    fapply(callback, nodeArgs).fail(deferred.reject);
    return deferred.promise;
}

/**
 * Passes a continuation to a Node function, which is called with the given
 * arguments provided individually, and returns a promise.
 *
 *      Q.nfcall(FS.readFile, __filename)
 *      .then(function (content) {
 *      })
 *
 */
Q.nfcall = nfcall;
function nfcall(callback/*, ...args */) {
    var nodeArgs = array_slice(arguments, 1);
    var deferred = defer();
    nodeArgs.push(deferred.makeNodeResolver());

    fapply(callback, nodeArgs).fail(deferred.reject);
    return deferred.promise;
}

/**
 * Wraps a NodeJS continuation passing function and returns an equivalent
 * version that returns a promise.
 *
 *      Q.nfbind(FS.readFile, __filename)("utf-8")
 *      .then(console.log)
 *      .done()
 *
 */
Q.nfbind = nfbind;
Q.denodeify = Q.nfbind; // synonyms
function nfbind(callback/*, ...args */) {
    var baseArgs = array_slice(arguments, 1);
    return function () {
        var nodeArgs = baseArgs.concat(array_slice(arguments));
        var deferred = defer();