/*

 * Copyright (c) 1996, 2013, 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 java.security;

import javax.security.auth.Subject;

/**

 * This interface represents the abstract notion of a principal, which

 * can be used to represent any entity, such as an individual, a

 * corporation, and a login id.

 *

 * @see java.security.cert.X509Certificate

 *

 * @author Li Gong

 * @since 1.1

 */

public interface Principal {

    /**

     * Compares this principal to the specified object.  Returns true

     * if the object passed in matches the principal represented by

     * the implementation of this interface.

     *

     * @param another principal to compare with.

     *

     * @return true if the principal passed in is the same as that

     * encapsulated by this principal, and false otherwise.

     */

    public boolean equals(Object another);

    /**

     * Returns a string representation of this principal.

     *

     * @return a string representation of this principal.

     */

    public String toString();

    /**

     * Returns a hashcode for this principal.

     *

     * @return a hashcode for this principal.

     */

    public int hashCode();

    /**

     * Returns the name of this principal.

     *

     * @return the name of this principal.

     */

    public String getName();

    /**

     * Returns true if the specified subject is implied by this principal.

     *

     * @implSpec

     * The default implementation of this method returns true if

     * {@code subject} is non-null and contains at least one principal that

     * is equal to this principal.

     *

     * <p>Subclasses may override this with a different implementation, if

     * necessary.

     *

     * @param subject the {@code Subject}

     * @return true if {@code subject} is non-null and is

     *              implied by this principal, or false otherwise.

     * @since 1.8

     */

    public default boolean implies(Subject subject) {

        if (subject == null)

            return false;

        return subject.getPrincipals().contains(this);

    }

}