q.js

// vim:ts=4:sts=4:sw=4:
/*!
 *
 * Copyright 2009-2012 Kris Kowal under the terms of the MIT
 * license found at http://github.com/kriskowal/q/raw/master/LICENSE
 *
 * With parts by Tyler Close
 * Copyright 2007-2009 Tyler Close under the terms of the MIT X license found
 * at http://www.opensource.org/licenses/mit-license.html
 * Forked at ref_send.js version: 2009-05-11
 *
 * With parts by Mark Miller
 * Copyright (C) 2011 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

(function (definition) {
    // Turn off strict mode for this function so we can assign to global.Q
    /*jshint strict: false, -W117*/

    // This file will function properly as a <script> tag, or a module
    // using CommonJS and NodeJS or RequireJS module formats.  In
    // Common/Node/RequireJS, the module exports the Q API and when
    // executed as a simple <script>, it creates a Q global instead.

    // Montage Require
    if (typeof bootstrap === "function") {
        bootstrap("promise", definition);

    // CommonJS
    } else if (typeof exports === "object") {
        module.exports = definition();

    // RequireJS
    } else if (typeof define === "function" && define.amd) {
        define(definition);

    // SES (Secure EcmaScript)
    } else if (typeof ses !== "undefined") {
        if (!ses.ok()) {
            return;
        } else {
            ses.makeQ = definition;
        }

    // <script>
    } else {
        Q = definition();
    }

})(function () {
"use strict";

// All code after this point will be filtered from stack traces reported
// by Q.
var qStartingLine = captureLine();
var qFileName;

// shims

// used for fallback in "allResolved"
var noop = function () {};

// use the fastest possible means to execute a task in a future turn
// of the event loop.
var nextTick;
if (typeof setImmediate === "function") {
    // In IE10, or use https://github.com/NobleJS/setImmediate
    if (typeof window !== "undefined") {
        nextTick = setImmediate.bind(window);
    } else {
        nextTick = setImmediate;
    }
} else if (typeof process !== "undefined") {
        // node
        nextTick = process.nextTick;
} else {
    (function () {
        // linked list of tasks (single, with head node)
        var head = {task: void 0, next: null};
        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
        for (var i = 0; i < this.length; i++) {
            if (this[i] === value) {
                return i;
            }
        }
        return -1;
    }
);

var array_map = uncurryThis(
    Array.prototype.map || function (callback, thisp) {
        var self = this;
        var collect = [];
        array_reduce(self, function (undefined, value, index) {
            collect.push(callback.call(thisp, value, index, self));
        }, void 0);
        return collect;
    }
);

var object_create = Object.create || function (prototype) {
    function Type() { }
    Type.prototype = prototype;
    return new Type();
};

var object_hasOwnProperty = uncurryThis(Object.prototype.hasOwnProperty);

var object_keys = Object.keys || function (object) {
    var keys = [];
    for (var key in object) {
        if (object_hasOwnProperty(object, key)) {
            keys.push(key);
        }
    }
    return keys;
};

var object_toString = uncurryThis(Object.prototype.toString);

// generator related shims

function isStopIteration(exception) {
    return (
        object_toString(exception) === "[object StopIteration]" ||
        exception instanceof QReturnValue
    );
}

var QReturnValue;
if (typeof ReturnValue !== "undefined") {
    QReturnValue = ReturnValue;
} else {
    QReturnValue = function (value) {
        this.value = value;
    };
}

// long stack traces

Q.longStackJumpLimit = 1;

var STACK_JUMP_SEPARATOR = "From previous event:";

function makeStackTraceLong(error, promise) {
    // If possible (that is, if in V8), transform the error stack
    // trace by removing Node and Q cruft, then concatenating with
    // the stack trace of the promise we are ``done``ing. See #57.
    if (promise.stack &&
        typeof error === "object" &&
        error !== null &&
        error.stack &&
        error.stack.indexOf(STACK_JUMP_SEPARATOR) === -1
    ) {
        error.stack = filterStackString(error.stack) +
            "\n" + STACK_JUMP_SEPARATOR + "\n" +
            filterStackString(promise.stack);
    }
}

function filterStackString(stackString) {
    var lines = stackString.split("\n");
    var desiredLines = [];
    for (var i = 0; i < lines.length; ++i) {
        var line = lines[i];

        if (!isInternalFrame(line) && !isNodeFrame(line)) {
            desiredLines.push(line);
        }
    }
    return desiredLines.join("\n");
}

function isNodeFrame(stackLine) {
    return stackLine.indexOf("(module.js:") !== -1 ||
           stackLine.indexOf("(node.js:") !== -1;
}

function isInternalFrame(stackLine) {
    var pieces = /at .+ \((.*):(\d+):\d+\)/.exec(stackLine);

    if (!pieces) {
        return false;
    }

    var fileName = pieces[1];
    var lineNumber = pieces[2];

    return fileName === qFileName &&
        lineNumber >= qStartingLine &&
        lineNumber <= qEndingLine;
}

// discover own file name and line number range for filtering stack
// traces
function captureLine() {
    if (Error.captureStackTrace) {
        var fileName, lineNumber;

        var oldPrepareStackTrace = Error.prepareStackTrace;

        Error.prepareStackTrace = function (error, frames) {
            fileName = frames[1].getFileName();
            lineNumber = frames[1].getLineNumber();
        };

        // teases call of temporary prepareStackTrace
        // JSHint and Closure Compiler generate known warnings here
        /*jshint expr: true */
        new Error().stack;

        Error.prepareStackTrace = oldPrepareStackTrace;
        qFileName = fileName;
        return lineNumber;
    }
}

// end of shims
// beginning of real work

/**
 * Creates fulfilled promises from non-promises,
 * Passes Q promises through,
 * Coerces thenables to Q promises.
 */
function Q(value) {
    return resolve(value);
}

/**
 * Performs a task in a future turn of the event loop.
 * @param {Function} task
 */
Q.nextTick = nextTick;

/**
 * Constructs a {promise, resolve} object.
 *
 * The resolver is a callback to invoke with a more resolved value for the
 * promise. To fulfill the promise, invoke the resolver with any value that is
 * not a function. To reject the promise, invoke the resolver with a rejection
 * object. To put the promise in the same state as another promise, invoke the
 * resolver with that other promise.
 */
Q.defer = defer;
function defer() {
    // if "pending" is an "Array", that indicates that the promise has not yet
    // been resolved.  If it is "undefined", it has been resolved.  Each
    // element of the pending array is itself an array of complete arguments to
    // forward to the resolved promise.  We coerce the resolution value to a
    // promise using the ref promise because it handles both fully
    // resolved values and other promises gracefully.
    var pending = [], progressListeners = [], resolvedPromise;

    var deferred = object_create(defer.prototype);
    var promise = object_create(makePromise.prototype);

    promise.promiseDispatch = function (resolve, op, operands) {
        var args = array_slice(arguments);
        if (pending) {
            pending.push(args);
            if (op === "when" && operands[1]) { // progress operand
                progressListeners.push(operands[1]);
            }
        } else {
            nextTick(function () {
                resolvedPromise.promiseDispatch.apply(resolvedPromise, args);
            });
        }
    };

    promise.valueOf = function () {
        if (pending) {
            return promise;
        }
        var nearer = valueOf(resolvedPromise);
        if (isPromise(nearer)) {
            resolvedPromise = nearer; // shorten chain
        }
        return nearer;
    };

    if (Error.captureStackTrace && Q.longStackJumpLimit > 0) {
        Error.captureStackTrace(promise, defer);

        // Reify the stack into a string by using the accessor; this prevents
        // memory leaks as per GH-111. At the same time, cut off the first line;
        // it's always just "[object Promise]\n", as per the `toString`.
        promise.stack = promise.stack.substring(
            promise.stack.indexOf("\n") + 1
        );
    }

    // NOTE: we do the checks for `resolvedPromise` in each method, instead of
    // consolidating them into `become`, since otherwise we'd create new
    // promises with the lines `become(whatever(value))`. See e.g. GH-252.

    function become(promise) {
        resolvedPromise = promise;

        array_reduce(pending, function (undefined, pending) {
            nextTick(function () {
                promise.promiseDispatch.apply(promise, pending);
            });
        }, void 0);

        pending = void 0;
        progressListeners = void 0;
    }

    deferred.promise = promise;
    deferred.resolve = function (value) {
        if (resolvedPromise) {
            return;
        }

        become(resolve(value));
    };

    deferred.fulfill = function (value) {
        if (resolvedPromise) {
            return;
        }

        become(fulfill(value));
    };
    deferred.reject = function (reason) {
        if (resolvedPromise) {
            return;
        }

        become(reject(reason));
    };
    deferred.notify = function (progress) {
        if (resolvedPromise) {
            return;
        }

        array_reduce(progressListeners, function (undefined, progressListener) {
            nextTick(function () {
                progressListener(progress);
            });
        }, void 0);
    };

    return deferred;
}

/**
 * Creates a Node-style callback that will resolve or reject the deferred
 * promise.
 * @returns a nodeback
 */
defer.prototype.makeNodeResolver = function () {
    var self = this;
    return function (error, value) {
        if (error) {
            self.reject(error);
        } else if (arguments.length > 2) {
            self.resolve(array_slice(arguments, 1));
        } else {
            self.resolve(value);
        }
    };
};

/**
 * @param makePromise {Function} a function that returns nothing and accepts
 * the resolve, reject, and notify functions for a deferred.
 * @returns a promise that may be resolved with the given resolve and reject
 * functions, or rejected by a thrown exception in makePromise
 */
Q.promise = promise;
function promise(makePromise) {
    var deferred = defer();
    fcall(
        makePromise,
        deferred.resolve,
        deferred.reject,
        deferred.notify
    ).fail(deferred.reject);
    return deferred.promise;
}

/**
 * Constructs a Promise with a promise descriptor object and optional fallback
 * function.  The descriptor contains methods like when(rejected), get(name),
 * set(name, value), post(name, args), and delete(name), which all
 * return either a value, a promise for a value, or a rejection.  The fallback
 * accepts the operation name, a resolver, and any further arguments that would
 * have been forwarded to the appropriate method above had a method been
 * provided with the proper name.  The API makes no guarantees about the nature
 * of the returned object, apart from that it is usable whereever promises are
 * bought and sold.
 */
Q.makePromise = makePromise;
function makePromise(descriptor, fallback, valueOf, exception, isException) {
    if (fallback === void 0) {
        fallback = function (op) {
            return reject(new Error(
                "Promise does not support operation: " + op
            ));
        };
    }

    var promise = object_create(makePromise.prototype);

    promise.promiseDispatch = function (resolve, op, args) {
        var result;
        try {
            if (descriptor[op]) {
                result = descriptor[op].apply(promise, args);
            } else {
                result = fallback.call(promise, op, args);
            }
        } catch (exception) {
            result = reject(exception);
        }
        if (resolve) {
            resolve(result);
        }
    };

    if (valueOf) {
        promise.valueOf = valueOf;
    }

    if (isException) {
        promise.exception = exception;
    }

    return promise;
}

// provide thenables, CommonJS/Promises/A
makePromise.prototype.then = function (fulfilled, rejected, progressed) {
    return when(this, fulfilled, rejected, progressed);
};

makePromise.prototype.thenResolve = function (value) {
    return when(this, function () { return value; });
};

makePromise.prototype.thenReject = function (reason) {
    return when(this, function () { throw reason; });
};

// Chainable methods
array_reduce(
    [
        "isFulfilled", "isRejected", "isPending",
        "dispatch",
        "when", "spread",
        "get", "set", "del", "delete",
        "post", "send", "invoke",
        "keys",
        "fapply", "fcall", "fbind",
        "all", "allResolved",
        "timeout", "delay",
        "catch", "finally", "fail", "fin", "progress", "done",
        "nfcall", "nfapply", "nfbind", "denodeify", "nbind",
        "ncall", "napply", "nbind",
        "npost", "nsend", "ninvoke",
        "nodeify"
    ],
    function (undefined, name) {
        makePromise.prototype[name] = function () {
            return Q[name].apply(
                Q,
                [this].concat(array_slice(arguments))
            );
        };
    },
    void 0
);

makePromise.prototype.toSource = function () {
    return this.toString();
};

makePromise.prototype.toString = function () {
    return "[object Promise]";
};

/**
 * If an object is not a promise, it is as "near" as possible.
 * If a promise is rejected, it is as "near" as possible too.
 * If it’s a fulfilled promise, the fulfillment value is nearer.
 * If it’s a deferred promise and the deferred has been resolved, the
 * resolution is "nearer".
 * @param object
 * @returns most resolved (nearest) form of the object
 */
Q.nearer = valueOf;
function valueOf(value) {
    if (isPromise(value)) {
        return value.valueOf();
    }
    return value;
}

/**
 * @returns whether the given object is a promise.
 * Otherwise it is a fulfilled value.
 */
Q.isPromise = isPromise;
function isPromise(object) {
    return object && typeof object.promiseDispatch === "function";
}

Q.isPromiseAlike = isPromiseAlike;
function isPromiseAlike(object) {
    return object && typeof object.then === "function";
}

/**
 * @returns whether the given object is a pending promise, meaning not
 * fulfilled or rejected.
 */
Q.isPending = isPending;
function isPending(object) {
    return !isFulfilled(object) && !isRejected(object);
}

/**
 * @returns whether the given object is a value or fulfilled
 * promise.
 */
Q.isFulfilled = isFulfilled;
function isFulfilled(object) {
    return !isPromiseAlike(valueOf(object));
}

/**
 * @returns whether the given object is a rejected promise.
 */
Q.isRejected = isRejected;
function isRejected(object) {
    object = valueOf(object);
    return isPromise(object) && "exception" in object;
}

// This promise library consumes exceptions thrown in handlers so they can be
// handled by a subsequent promise.  The exceptions get added to this array when
// they are created, and removed when they are handled.  Note that in ES6 or
// shimmed environments, this would naturally be a `Set`.
var unhandledReasons = Q.unhandledReasons = [];
var unhandledRejections = [];
var unhandledReasonsDisplayed = false;
function displayUnhandledReasons() {
    if (
        !unhandledReasonsDisplayed &&
        typeof window !== "undefined" &&
        !window.Touch &&
        window.console
    ) {
        console.warn("[Q] Unhandled rejection reasons (should be empty):",
                     unhandledReasons);
    }

    unhandledReasonsDisplayed = true;
}

// Show unhandled rejection reasons if Node exits without handling an
// outstanding rejection.  (Note that Browserify presently produces a process
// global without the `EventEmitter` `on` method.)
if (typeof process !== "undefined" && process.on) {
    process.on("exit", function () {
        for (var i = 0; i < unhandledReasons.length; i++) {
            var reason = unhandledReasons[i];
            if (reason && typeof reason.stack !== "undefined") {
                console.warn("Unhandled rejection reason:", reason.stack);
            } else {
                console.warn("Unhandled rejection reason (no stack):", reason);
            }
        }
    });
}

/**
 * Constructs a rejected promise.
 * @param reason value describing the failure
 */
Q.reject = reject;
function reject(reason) {
    var rejection = makePromise({
        "when": function (rejected) {
            // note that the error has been handled
            if (rejected) {
                var at = array_indexOf(unhandledRejections, this);
                if (at !== -1) {
                    unhandledRejections.splice(at, 1);
                    unhandledReasons.splice(at, 1);
                }
            }
            return rejected ? rejected(reason) : this;
        }
    }, function fallback() {
        return reject(reason);
    }, function valueOf() {
        return this;
    }, reason, true);

    // Note that the reason has not been handled.
    displayUnhandledReasons();
    unhandledRejections.push(rejection);
    unhandledReasons.push(reason);

    return rejection;
}

/**
 * Constructs a fulfilled promise for an immediate reference.
 * @param value immediate reference
 */
Q.fulfill = fulfill;
function fulfill(object) {
    return makePromise({
        "when": function () {
            return object;
        },
        "get": function (name) {
            return object[name];
        },
        "set": function (name, value) {
            object[name] = value;
        },
        "delete": function (name) {
            delete object[name];
        },
        "post": function (name, args) {
            // Mark Miller proposes that post with no name should apply a
            // promised function.
            if (name === null || name === void 0) {
                return object.apply(void 0, args);
            } else {
                return object[name].apply(object, args);
            }
        },
        "apply": function (thisP, args) {
            return object.apply(thisP, args);
        },
        "keys": function () {
            return object_keys(object);
        }
    }, void 0, function valueOf() {
        return object;
    });
}

/**
 * Constructs a promise for an immediate reference, passes promises through, or
 * coerces promises from different systems.
 * @param value immediate reference or promise
 */
Q.resolve = resolve;
function resolve(value) {
    // If the object is already a Promise, return it directly.  This enables
    // the resolve function to both be used to created references from objects,
    // but to tolerably coerce non-promises to promises.
    if (isPromise(value)) {
        return value;
    }
    // In order to break infinite recursion or loops between `then` and
    // `resolve`, it is necessary to attempt to extract fulfilled values
    // out of foreign promise implementations before attempting to wrap
    // them as unresolved promises.  It is my hope that other
    // implementations will implement `valueOf` to synchronously extract
    // the fulfillment value from their fulfilled promises.  If the
    // other promise library does not implement `valueOf`, the
    // implementations on primordial prototypes are harmless.
    value = valueOf(value);
    // assimilate thenables, CommonJS/Promises/A+
    if (isPromiseAlike(value)) {
        return coerce(value);
    } else {
        return fulfill(value);
    }
}

/**
 * Converts thenables to Q promises.
 * @param promise thenable promise
 * @returns a Q promise
 */
function coerce(promise) {
    var deferred = defer();
    nextTick(function () {
        try {
            promise.then(deferred.resolve, deferred.reject, deferred.notify);
        } catch (exception) {
            deferred.reject(exception);
        }
    });
    return deferred.promise;
}

/**
 * Annotates an object such that it will never be
 * transferred away from this process over any promise
 * communication channel.
 * @param object
 * @returns promise a wrapping of that object that
 * additionally responds to the "isDef" message
 * without a rejection.
 */
Q.master = master;
function master(object) {
    return makePromise({
        "isDef": function () {}
    }, function fallback(op, args) {
        return dispatch(object, op, args);
    }, function () {
        return valueOf(object);
    });
}

/**
 * Registers an observer on a promise.
 *
 * Guarantees:
 *
 * 1. that fulfilled and rejected will be called only once.
 * 2. that either the fulfilled callback or the rejected callback will be
 *    called, but not both.
 * 3. that fulfilled and rejected will not be called in this turn.
 *
 * @param value      promise or immediate reference to observe
 * @param fulfilled  function to be called with the fulfilled value
 * @param rejected   function to be called with the rejection exception
 * @param progressed function to be called on any progress notifications
 * @return promise for the return value from the invoked callback
 */
Q.when = when;
function when(value, fulfilled, rejected, progressed) {
    var deferred = defer();
    var done = false;   // ensure the untrusted promise makes at most a
                        // single call to one of the callbacks

    function _fulfilled(value) {
        try {
            return typeof fulfilled === "function" ? fulfilled(value) : value;
        } catch (exception) {
            return reject(exception);
        }
    }

    function _rejected(exception) {
        if (typeof rejected === "function") {
            makeStackTraceLong(exception, resolvedValue);
            try {
                return rejected(exception);
            } catch (newException) {
                return reject(newException);
            }
        }
        return reject(exception);
    }

    function _progressed(value) {
        return typeof progressed === "function" ? progressed(value) : value;
    }

    var resolvedValue = resolve(value);
    nextTick(function () {
        resolvedValue.promiseDispatch(function (value) {
            if (done) {
                return;
            }
            done = true;

            deferred.resolve(_fulfilled(value));
        }, "when", [function (exception) {
            if (done) {
                return;
            }
            done = true;

            deferred.resolve(_rejected(exception));
        }]);
    });

    // Progress propagator need to be attached in the current tick.
    resolvedValue.promiseDispatch(void 0, "when", [void 0, function (value) {
        var newValue;
        var threw = false;
        try {
            newValue = _progressed(value);
        } catch (e) {
            threw = true;
            if (Q.onerror) {
                Q.onerror(e);
            } else {
                throw e;
            }
        }

        if (!threw) {
            deferred.notify(newValue);
        }
    }]);

    return deferred.promise;
}

/**
 * Spreads the values of a promised array of arguments into the
 * fulfillment callback.
 * @param fulfilled callback that receives variadic arguments from the
 * promised array
 * @param rejected callback that receives the exception if the promise
 * is rejected.
 * @returns a promise for the return value or thrown exception of
 * either callback.
 */
Q.spread = spread;
function spread(promise, fulfilled, rejected) {
    return when(promise, function (valuesOrPromises) {
        return all(valuesOrPromises).then(function (values) {
            return fulfilled.apply(void 0, values);
        }, rejected);
    }, rejected);
}

/**
 * The async function is a decorator for generator functions, turning
 * them into asynchronous generators.  This presently only works in
 * Firefox/Spidermonkey, however, this code does not cause syntax
 * errors in older engines.  This code should continue to work and
 * will in fact improve over time as the language improves.
 *
 * Decorates a generator function such that:
 *  - it may yield promises
 *  - execution will continue when that promise is fulfilled
 *  - the value of the yield expression will be the fulfilled value
 *  - it returns a promise for the return value (when the generator
 *    stops iterating)
 *  - the decorated function returns a promise for the return value
 *    of the generator or the first rejected promise among those
 *    yielded.
 *  - if an error is thrown in the generator, it propagates through
 *    every following yield until it is caught, or until it escapes
 *    the generator function altogether, and is translated into a
 *    rejection for the promise returned by the decorated generator.
 *  - in present implementations of generators, when a generator
 *    function is complete, it throws ``StopIteration``, ``return`` is
 *    a syntax error in the presence of ``yield``, so there is no
 *    observable return value. There is a proposal[1] to add support
 *    for ``return``, which would permit the value to be carried by a
 *    ``StopIteration`` instance, in which case it would fulfill the
 *    promise returned by the asynchronous generator.  This can be
 *    emulated today by throwing StopIteration explicitly with a value
 *    property.
 *
 *  [1]: http://wiki.ecmascript.org/doku.php?id=strawman:async_functions#reference_implementation
 *
 */
Q.async = async;
function async(makeGenerator) {
    return function () {
        // when verb is "send", arg is a value
        // when verb is "throw", arg is an exception
        function continuer(verb, arg) {
            var result;
            try {
                result = generator[verb](arg);
            } catch (exception) {
                if (isStopIteration(exception)) {
                    return exception.value;
                } else {
                    return reject(exception);
                }
            }
            return when(result, callback, errback);
        }
        var generator = makeGenerator.apply(this, arguments);
        var callback = continuer.bind(continuer, "send");
        var errback = continuer.bind(continuer, "throw");
        return callback();
    };
}

/**
 * Throws a ReturnValue exception to stop an asynchronous generator.
 * Only useful presently in Firefox/SpiderMonkey since generators are
 * implemented.
 * @param value the return value for the surrounding generator
 * @throws ReturnValue exception with the value.
 * @example
 * Q.async(function () {
 *      var foo = yield getFooPromise();
 *      var bar = yield getBarPromise();
 *      Q.return(foo + bar);
 * })
 */
Q["return"] = _return;
function _return(value) {
    throw new QReturnValue(value);
}

/**
 * The promised function decorator ensures that any promise arguments
 * are resolved and passed as values (`this` is also resolved and passed
 * as a value).  It will also ensure that the result of a function is
 * always a promise.
 *
 * @example
 * var add = Q.promised(function (a, b) {
 *     return a + b;
 * });
 * add(Q.resolve(a), Q.resolve(B));
 *
 * @param {function} callback The function to decorate
 * @returns {function} a function that has been decorated.
 */
Q.promised = promised;
function promised(callback) {
    return function () {
        return spread([this, all(arguments)], function (self, args) {
            return callback.apply(self, args);
        });
    };
}

/**
 * sends a message to a value in a future turn
 * @param object* the recipient
 * @param op the name of the message operation, e.g., "when",
 * @param args further arguments to be forwarded to the operation
 * @returns result {Promise} a promise for the result of the operation
 */
Q.dispatch = dispatch;
function dispatch(object, op, args) {
    var deferred = defer();
    nextTick(function () {
        resolve(object).promiseDispatch(deferred.resolve, op, args);
    });
    return deferred.promise;
}

/**
 * Constructs a promise method that can be used to safely observe resolution of
 * a promise for an arbitrarily named method like "propfind" in a future turn.
 *
 * "dispatcher" constructs methods like "get(promise, name)" and "set(promise)".
 */
Q.dispatcher = dispatcher;
function dispatcher(op) {
    return function (object) {
        var args = array_slice(arguments, 1);
        return dispatch(object, op, args);
    };
}

/**
 * Gets the value of a property in a future turn.
 * @param object    promise or immediate reference for target object
 * @param name      name of property to get
 * @return promise for the property value
 */
Q.get = dispatcher("get");

/**
 * Sets the value of a property in a future turn.
 * @param object    promise or immediate reference for object object
 * @param name      name of property to set
 * @param value     new value of property
 * @return promise for the return value
 */
Q.set = dispatcher("set");

/**
 * Deletes a property in a future turn.
 * @param object    promise or immediate reference for target object
 * @param name      name of property to delete
 * @return promise for the return value
 */
Q["delete"] = // XXX experimental
Q.del = dispatcher("delete");

/**
 * Invokes a method in a future turn.
 * @param object    promise or immediate reference for target object
 * @param name      name of method to invoke
 * @param value     a value to post, typically an array of
 *                  invocation arguments for promises that
 *                  are ultimately backed with `resolve` values,
 *                  as opposed to those backed with URLs
 *                  wherein the posted value can be any
 *                  JSON serializable object.
 * @return promise for the return value
 */
// bound locally because it is used by other methods
var post = Q.post = dispatcher("post");

/**
 * Invokes a method in a future turn.
 * @param object    promise or immediate reference for target object
 * @param name      name of method to invoke
 * @param ...args   array of invocation arguments
 * @return promise for the return value
 */
Q.send = send;
Q.invoke = send; // synonyms
function send(value, name) {
    var args = array_slice(arguments, 2);
    return post(value, name, args);
}

/**
 * Applies the promised function in a future turn.
 * @param object    promise or immediate reference for target function
 * @param args      array of application arguments
 */
Q.fapply = fapply;
function fapply(value, args) {
    return dispatch(value, "apply", [void 0, args]);
}

/**
 * Calls the promised function in a future turn.
 * @param object    promise or immediate reference for target function
 * @param ...args   array of application arguments
 */
Q["try"] = fcall; // XXX experimental
Q.fcall = fcall;
function fcall(value) {
    var args = array_slice(arguments, 1);
    return fapply(value, args);
}

/**
 * Binds the promised function, transforming return values into a fulfilled
 * promise and thrown errors into a rejected one.
 * @param object    promise or immediate reference for target function
 * @param ...args   array of application arguments
 */
Q.fbind = fbind;
function fbind(value) {
    var args = array_slice(arguments, 1);
    return function fbound() {
        var allArgs = args.concat(array_slice(arguments));
        return dispatch(value, "apply", [this, allArgs]);
    };
}

/**
 * Requests the names of the owned properties of a promised
 * object in a future turn.
 * @param object    promise or immediate reference for target object
 * @return promise for the keys of the eventually resolved object
 */
Q.keys = dispatcher("keys");

/**
 * Turns an array of promises into a promise for an array.  If any of
 * the promises gets rejected, the whole array is rejected immediately.
 * @param {Array*} an array (or promise for an array) of values (or
 * promises for values)
 * @returns a promise for an array of the corresponding values
 */
// By Mark Miller
// http://wiki.ecmascript.org/doku.php?id=strawman:concurrency&rev=1308776521#allfulfilled
Q.all = all;
function all(promises) {
    return when(promises, function (promises) {
        var countDown = 0;
        var deferred = defer();
        array_reduce(promises, function (undefined, promise, index) {
            if (isFulfilled(promise)) {
                promises[index] = valueOf(promise);
            } else {
                ++countDown;
                when(promise, function (value) {
                    promises[index] = value;
                    if (--countDown === 0) {
                        deferred.resolve(promises);
                    }
                }, deferred.reject);
            }
        }, void 0);
        if (countDown === 0) {
            deferred.resolve(promises);
        }
        return deferred.promise;
    });
}

/**
 * Waits for all promises to be resolved, either fulfilled or
 * rejected.  This is distinct from `all` since that would stop
 * waiting at the first rejection.  The promise returned by
 * `allResolved` will never be rejected.
 * @param promises a promise for an array (or an array) of promises
 * (or values)
 * @return a promise for an array of promises
 */
Q.allResolved = allResolved;
function allResolved(promises) {
    return when(promises, function (promises) {
        promises = array_map(promises, resolve);
        return when(all(array_map(promises, function (promise) {
            return when(promise, noop, noop);
        })), function () {
            return promises;
        });
    });
}

/**
 * Captures the failure of a promise, giving an oportunity to recover
 * with a callback.  If the given promise is fulfilled, the returned
 * promise is fulfilled.
 * @param {Any*} promise for something
 * @param {Function} callback to fulfill the returned promise if the
 * given promise is rejected
 * @returns a promise for the return value of the callback
 */
Q["catch"] = // XXX experimental
Q.fail = fail;
function fail(promise, rejected) {
    return when(promise, void 0, rejected);
}

/**
 * Attaches a listener that can respond to progress notifications from a
 * promise's originating deferred. This listener receives the exact arguments
 * passed to ``deferred.notify``.
 * @param {Any*} promise for something
 * @param {Function} callback to receive any progress notifications
 * @returns the given promise, unchanged
 */
Q.progress = progress;
function progress(promise, progressed) {
    return when(promise, void 0, void 0, progressed);
}

/**
 * Provides an opportunity to observe the rejection of a promise,
 * regardless of whether the promise is fulfilled or rejected.  Forwards
 * the resolution to the returned promise when the callback is done.
 * The callback can return a promise to defer completion.
 * @param {Any*} promise
 * @param {Function} callback to observe the resolution of the given
 * promise, takes no arguments.
 * @returns a promise for the resolution of the given promise when
 * ``fin`` is done.
 */
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
 * @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) {
    var deferred = defer();
    var timeoutId = setTimeout(function () {
        deferred.reject(new Error("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();
        nodeArgs.push(deferred.makeNodeResolver());

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

Q.nbind = nbind;
function nbind(callback, thisArg /*, ... args*/) {
    var baseArgs = array_slice(arguments, 2);
    return function () {
        var nodeArgs = baseArgs.concat(array_slice(arguments));
        var deferred = defer();
        nodeArgs.push(deferred.makeNodeResolver());

        function bound() {
            return callback.apply(thisArg, arguments);
        }

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

/**
 * Calls a method of a Node-style object that accepts a Node-style
 * callback with a given array of arguments, plus a provided callback.
 * @param object an object that has the named method
 * @param {String} name name of the method of object
 * @param {Array} args arguments to pass to the method; the callback
 * will be provided by Q and appended to these arguments.
 * @returns a promise for the value or error
 */
Q.npost = npost;
function npost(object, name, args) {
    var nodeArgs = array_slice(args || []);
    var deferred = defer();
    nodeArgs.push(deferred.makeNodeResolver());

    post(object, name, nodeArgs).fail(deferred.reject);
    return deferred.promise;
}

/**
 * Calls a method of a Node-style object that accepts a Node-style
 * callback, forwarding the given variadic arguments, plus a provided
 * callback argument.
 * @param object an object that has the named method
 * @param {String} name name of the method of object
 * @param ...args arguments to pass to the method; the callback will
 * be provided by Q and appended to these arguments.
 * @returns a promise for the value or error
 */
Q.nsend = nsend;
Q.ninvoke = Q.nsend; // synonyms
function nsend(object, name /*, ...args*/) {
    var nodeArgs = array_slice(arguments, 2);
    var deferred = defer();
    nodeArgs.push(deferred.makeNodeResolver());
    post(object, name, nodeArgs).fail(deferred.reject);
    return deferred.promise;
}

Q.nodeify = nodeify;
function nodeify(promise, nodeback) {
    if (nodeback) {
        promise.then(function (value) {
            nextTick(function () {
                nodeback(null, value);
            });
        }, function (error) {
            nextTick(function () {
                nodeback(error);
            });
        });
    } else {
        return promise;
    }
}

// All code before this point will be filtered from stack traces.
var qEndingLine = captureLine();

return Q;

});