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 : 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    }