raptor/lib/raptor/promises/promises.js

RaptorJS provides an AMD module loader that works in Node, Rhino and the web browser. It also includes various sub-modules to support building optimized web applications.

define('raptor/promises', function() {
    "use strict";
    
    var resolvedPromise = null;

    return {
        isPromise: function(promise) {
            return promise != null && typeof promise.then === 'function';
        },

        resolved: function() {
            if (!resolvedPromise) {
                var deferred = this.defer();
                deferred.resolve();
                resolvedPromise = deferred.promise;
            }
            return resolvedPromise;
        },

        makePromise: function(val) {
            if (this.isPromise(val)) {
                return val;
            }
            else {
                var deferred = this.defer();
                deferred.resolve(val);    
                return deferred.promise;
            }
        },

        valueOfPromise: function(p) {
            if (p && typeof p.inspect === 'function') {
                var inspected = p.inspect();
                if (inspected.state === 'fulfilled') {
                    return inspected.value;
                }
                else {
                    return undefined;
                }
            }
            else {
                return p;
            }
        },

        immediateThen: function(p, resolvedCallback, rejectedCallback) {
            var result;

            if (p && typeof p.inspect === 'function') {
                var inspected = p.inspect();
                if (inspected.state === 'fulfilled') {
                    result = resolvedCallback(inspected.value);
                    return this.makePromise(result); // Make sure it is a promise
                }
                else if (inspected.state === 'rejected') {
                    result = rejectedCallback(inspected.reason);
                    return this.makePromise(result); // Make sure it is a promise
                }
            }

            // Fall-through for the pending state or lack of "inspect"
            return this.makePromise(p)
                .then(resolvedCallback, rejectedCallback);
        }
    };
});