/*

 * 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 com.sun.tools.internal.xjc.reader.gbind;

import java.util.Collections;

import java.util.Iterator;

/**

 * A set over a list of {@link Element}.

 *

 * @author Kohsuke Kawaguchi

 */

interface ElementSet extends Iterable<Element> {

    /**

     * For each element in this set, adds an edge to the given element.

     */

    void addNext(Element element);

    public static final ElementSet EMPTY_SET = new ElementSet() {

        public void addNext(Element element) {

            // noop

        }

        public boolean contains(ElementSet element) {

            return this==element;

        }

        public Iterator<Element> iterator() {

            return Collections.<Element>emptySet().iterator();

        }

    };

    /**

     * Doesn't have to be strict (it's OK for this method to return false

     * when it's actually true) since this is used just for optimization.

     *

     * (Erring on the other side is NG)

     */

    boolean contains(ElementSet rhs);

}