001    /*
002     * Copyright (C) 2012 eXo Platform SAS.
003     *
004     * This is free software; you can redistribute it and/or modify it
005     * under the terms of the GNU Lesser General Public License as
006     * published by the Free Software Foundation; either version 2.1 of
007     * the License, or (at your option) any later version.
008     *
009     * This software is distributed in the hope that it will be useful,
010     * but WITHOUT ANY WARRANTY; without even the implied warranty of
011     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
012     * Lesser General Public License for more details.
013     *
014     * You should have received a copy of the GNU Lesser General Public
015     * License along with this software; if not, write to the Free
016     * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
017     * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
018     */
019    package org.crsh.shell.impl.command.spi;
020    
021    import org.crsh.command.CommandContext;
022    import org.crsh.console.KeyHandler;
023    import org.crsh.io.Filter;
024    
025    import java.io.IOException;
026    
027    /**
028     * A command invoker is a filter for a {@link org.crsh.command.CommandContext} kind of consumer.
029     *
030     * @param <C> the consumed element generic type
031     * @param <P> the produced element generic type
032     */
033    public abstract class CommandInvoker<C, P> implements Filter<C, P, CommandContext<? super P>> {
034    
035      /**
036       * Invoke the command.
037       *
038       * @param consumer the consumer for this invocation
039       * @throws IOException any io exception
040       */
041      public final void invoke(CommandContext<? super P> consumer) throws IOException {
042        try {
043          open(consumer);
044        }
045        finally {
046          try {
047            flush();
048          }
049          finally {
050            close();
051          }
052        }
053      }
054    
055      /**
056       * Return the key handler or null if the invoker cannot handler key events.
057       *
058       * @return the key handler
059       */
060      public KeyHandler getKeyHandler() {
061        return null;
062      }
063    }