/*

 * Copyright (C) 2007-2010 Júlio Vilmar Gesser.

 * Copyright (C) 2011, 2013-2021 The JavaParser Team.

 *

 * This file is part of JavaParser.

 *

 * JavaParser can be used either under the terms of

 * a) the GNU Lesser General Public License as published by

 *     the Free Software Foundation, either version 3 of the License, or

 *     (at your option) any later version.

 * b) the terms of the Apache License

 *

 * You should have received a copy of both licenses in LICENCE.LGPL and

 * LICENCE.APACHE. Please refer to those files for details.

 *

 * JavaParser 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 Lesser General Public License for more details.

 */

package com.github.javaparser.ast.observer;

/**

 * Observable element.

 */

public interface Observable {

    /**

     * Register an observer.

     */

    void register(AstObserver observer);

    /**

     * Unregister an observer. If the given observer was not registered there are no effects.

     */

    void unregister(AstObserver observer);

    /**

     * Was this observer registered?

     * Note that equals is used to determine if the given observer was registered.

     */

    boolean isRegistered(AstObserver observer);

}