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
020 package org.crsh.command;
021
022 import org.crsh.text.RenderPrintWriter;
023
024 import java.util.LinkedList;
025
026 public abstract class AbstractCommand {
027
028 /** . */
029 private LinkedList<InvocationContext<?>> stack;
030
031 /** The current context. */
032 protected RuntimeContext context;
033
034 /** The current output. */
035 protected RenderPrintWriter out;
036
037 protected AbstractCommand() {
038 this.stack = null;
039 this.context = null;
040 }
041
042 public final void pushContext(InvocationContext<?> context) throws NullPointerException {
043 if (context == null) {
044 throw new NullPointerException();
045 }
046
047 //
048 if (stack == null) {
049 stack = new LinkedList<InvocationContext<?>>();
050 }
051
052 // Save current context (is null the first time)
053 stack.addLast((InvocationContext<?>)this.context);
054
055 // Set new context
056 this.context = context;
057 this.out = context.getWriter();
058 }
059
060 public final InvocationContext<?> popContext() {
061 if (stack != null && stack.size() > 0) {
062 InvocationContext context = (InvocationContext)this.context;
063 this.context = stack.removeLast();
064 this.out = this.context != null ? ((InvocationContext)this.context).getWriter() : null;
065 return context;
066 } else {
067 return null;
068 }
069 }
070
071 public final InvocationContext<?> peekContext() {
072 return (InvocationContext<?>)context;
073 }
074 }