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
020package org.crsh.command;
021
022import org.crsh.text.RenderPrintWriter;
023
024import java.util.LinkedList;
025
026public abstract class AbstractCommand {
027
028  /** . */
029  private LinkedList<InvocationContext<?>> stack;
030
031  /** The current context : need to find a way to make not that public. */
032  public 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}