Source/JavaScriptCore/builtins/ObjectConstructor.js

/*
 * Copyright (C) 2015 Jordan Harband. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

function assign(target/*[*/, /*...*/sources/*] */) {
    "use strict";

    if (target == null)
        throw new @TypeError("can't convert " + target + " to object");

    var objTarget = @Object(target);
    var s, nextSource, from, i, keys, nextKey, desc;
    for (s = 1; s < arguments.length; ++s) {
        nextSource = arguments[s];
        if (nextSource != null) {
            from = @Object(nextSource);
            // TODO: replace @objectKeys + @objectGetOwnPropertySymbols with single @OwnPropertyKeys c++ operation
            keys = @objectKeys(from);
            for (i = 0; i < keys.length; ++i) {
                nextKey = keys[i];
                desc = @objectGetOwnPropertyDescriptor(from, nextKey);
                if (typeof desc !== "undefined" && desc.enumerable) {
                    objTarget[nextKey] = from[nextKey];
                }
            }
            keys = @objectGetOwnPropertySymbols(from);
            for (i = 0; i < keys.length; ++i) {
                nextKey = keys[i];
                desc = @objectGetOwnPropertyDescriptor(from, nextKey);
                if (typeof desc !== "undefined" && desc.enumerable) {
                    objTarget[nextKey] = from[nextKey];
                }
            }
        }
    }
    return objTarget;
}