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 */
019package org.crsh.shell.impl.command.spi;
020
021import org.crsh.command.CommandContext;
022import org.crsh.console.KeyHandler;
023import org.crsh.io.Filter;
024
025import 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 */
033public 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}