Gatekeeper.java

/*
 * Copyright 2012 Cedric Hauber
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

package org.jboss.errai.mvp.client.places;

/**
 * Inherit from this class to define a gatekeeper that locks access to your
 * {@link Place} in specific situation. For example:
 *
 * <pre>
 * public class AdminGatekeeper implements Gatekeeper {
 *
 *   private final CurrentUser currentUser;
 *
 *  {@code @}Inject
 *   public AdminGatekeeper( CurrentUser currentUser ) {
 *     this.currentUser = currentUser;
 *   }
 *
 *  {@code @}Override
 *   public boolean canReveal() {
 *     return currentUser.isAdministrator();
 *   }
 *
 * }
 * </pre>
 *
 * You must also make sure that your custom Ginjector provides a {@code get}
 * method returning this {@link Gatekeeper} if you want to use it with the
 * {@link org.jboss.errai.mvp.client.annotations.UseGatekeeper} annotation.
 * <p />
 * You should usually bind your {@link Gatekeeper} as a singleton.
 *
 * @author Philippe Beaudoin
 * @author Olivier Monaco
 */
public interface Gatekeeper {
  /**
   * Checks whether or not the {@link Place} controlled by this gatekeeper can
   * be revealed.
   *
   * @return {@code true} if the {@link Place} can be revealed, {@code false}
   *         otherwise.
   */
  boolean canReveal();
}