/*

 * Copyright (c) 2003, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.reflect.generics.scope;

import java.lang.reflect.TypeVariable;

/**

 * This class is used to provide enclosing scopes for top level classes.

 * We cannot use {@code null} to represent such a scope, since the

 * enclosing scope is computed lazily, and so the field storing it is

 * null until it has been computed. Therefore, {@code null} is reserved

 * to represent an as-yet-uncomputed scope, and cannot be used for any

 * other kind of scope.

 */

public class DummyScope implements Scope {

    // Caches the unique instance of this class; instances contain no data

    // so we can use the singleton pattern

    private static final DummyScope singleton = new DummyScope();

    // constructor is private to enforce use of factory method

    private DummyScope(){}

    /**

     * Factory method. Enforces the singleton pattern - only one

     * instance of this class ever exists.

     */

    public static DummyScope make() {

        return singleton;

    }

    /**

     * Lookup a type variable in the scope, using its name. Always returns

     * {@code null}.

     * @param name - the name of the type variable being looked up

     * @return  null

     */

    public TypeVariable<?> lookup(String name) {return null;}

}