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.keyboard.KeyHandler; 023 import org.crsh.stream.Filter; 024 import org.crsh.text.ScreenContext; 025 026 import java.io.IOException; 027 028 /** 029 * A command invoker is a filter for a {@link org.crsh.command.CommandContext} kind of consumer. 030 * 031 * @param <C> the consumed element generic type 032 * @param <P> the produced element generic type 033 */ 034 public abstract class CommandInvoker<C, P> implements Filter<C, P, CommandContext<? super P>> { 035 036 /** 037 * Invoke the command. 038 * 039 * @param consumer the consumer for this invocation 040 * @throws IOException any io exception 041 * @throws CommandException anything command exception 042 */ 043 public final void invoke(CommandContext<? super P> consumer) throws IOException, CommandException { 044 try { 045 open(consumer); 046 } 047 finally { 048 try { 049 flush(); 050 } 051 finally { 052 close(); 053 } 054 } 055 } 056 057 @Override 058 public abstract void flush() throws IOException; 059 060 @Override 061 public abstract void provide(C element) throws IOException, CommandException; 062 063 @Override 064 public abstract void open(CommandContext<? super P> consumer) throws IOException, CommandException; 065 066 @Override 067 public abstract void close() throws IOException, CommandException; 068 069 /** 070 * Provide an opportunity for the command to implement screen context. 071 * 072 * @return the screen context 073 */ 074 public ScreenContext getScreenContext() { 075 return null; 076 } 077 078 /** 079 * Return the key handler or null if the invoker cannot handler key events. 080 * 081 * @return the key handler 082 */ 083 public KeyHandler getKeyHandler() { 084 return null; 085 } 086 }