bluebird/js/zalgo/thenable.js

Full featured Promises/A+ implementation with exceptionally good performance

/**
 * Copyright (c) 2013 Petka Antonov
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:</p>
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
"use strict";
var ASSERT = require("./assert.js");
var util = require( "./util.js" );
var async = require( "./async.js" );
var errorObj = util.errorObj;
function Thenable() {
    this.errorObj = errorObj;
    this.__id__ = 0;
    this.treshold = 1000;
    this.thenableCache = new Array( this.treshold );
    this.promiseCache = new Array( this.treshold );
    this._compactQueued = false;
}
Thenable.prototype.couldBe = function Thenable$couldBe( ret ) {
    if( ret === null ||
        typeof ret === "undefined" ||
        typeof ret === "string" ||
        typeof ret === "boolean" ||
        typeof ret === "number" ) {
        return false;
    }
    var id = ret.__id_$thenable__;
    if( typeof id === "number" &&
        this.thenableCache[id] !== void 0 ) {
        return true;
    }
    return ("then" in ret);
};

Thenable.prototype.is = function Thenable$is( ret, ref ) {
    var id = ret.__id_$thenable__;
    if( typeof id === "number" &&
        this.thenableCache[id] !== void 0 ) {
        ref.ref = this.thenableCache[id];
        ref.promise = this.promiseCache[id];
        return true;
    }
    return this._thenableSlowCase( ret, ref );
};

Thenable.prototype.addCache = function Thenable$_addCache( thenable, promise ) {
    var id = this.__id__;
    this.__id__ = id + 1;
    var descriptor = this._descriptor( id );
    Object.defineProperty( thenable, "__id_$thenable__", descriptor );
    this.thenableCache[id] = thenable;
    this.promiseCache[id] = promise;
    if( this.thenableCache.length > this.treshold &&
        !this._compactQueued) {
        this._compactQueued = true;
        async.invokeLater( this._compactCache, this, void 0 );
    }
};

Thenable.prototype.deleteCache = function Thenable$deleteCache( thenable ) {
    var id = thenable.__id_$thenable__;
    if( id === -1 ) {
        return;
    }
    this.thenableCache[id] = void 0;
    this.promiseCache[id] = void 0;
    thenable.__id_$thenable__ = -1;};

var descriptor = {
    value: 0,
    enumerable: false,
    writable: true,
    configurable: true
};
Thenable.prototype._descriptor = function Thenable$_descriptor( id ) {
    descriptor.value = id;
    return descriptor;
};

Thenable.prototype._compactCache = function Thenable$_compactCache() {
    var arr = this.thenableCache;
    var promiseArr = this.promiseCache;
    var skips = 0;
    var j = 0;
    for( var i = 0, len = arr.length; i < len; ++i ) {
        var item = arr[ i ];
        if( item === void 0 ) {
            skips++;
        }
        else {
            promiseArr[ j ] = promiseArr[ i ];
            item.__id_$thenable__ = j;
            arr[ j++ ] = item;
        }
    }
    var newId = arr.length - skips;
    if( newId === this.__id__ ) {
        this.treshold *= 2;
    }
    else for( var i = newId, len = arr.length; i < len; ++i ) {
        promiseArr[ j ] = arr[ i ] = void 0;
    }

    this.__id__ = newId;
    this._compactQueued = false;
};

Thenable.prototype._thenableSlowCase =
function Thenable$_thenableSlowCase( ret, ref ) {
    try {
        var then = ret.then;
        if( typeof then === "function" ) {
            ref.ref = then;
            return true;
        }
        return false;
    }
    catch(e) {
        this.errorObj.e = e;
        ref.ref = this.errorObj;
        return true;
    }
};

module.exports = Thenable;