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.pipeline;
021    
022    import org.crsh.command.CommandContext;
023    import org.crsh.command.CommandInvoker;
024    import org.crsh.text.Chunk;
025    
026    import java.io.IOException;
027    
028    public class PipeLine extends CommandInvoker<Void, Chunk> {
029    
030      /** . */
031      private final CommandInvoker[] invokers;
032    
033      /** . */
034      private CommandContext<?> current;
035    
036      public PipeLine(CommandInvoker[] invokers) {
037        this.invokers = invokers;
038        this.current = null;
039      }
040    
041      public Class<Void> getConsumedType() {
042        throw new UnsupportedOperationException();
043      }
044    
045      public Class<Chunk> getProducedType() {
046        throw new UnsupportedOperationException();
047      }
048    
049      public void open(CommandContext<? super Chunk> consumer) {
050        open(0, consumer);
051      }
052    
053      private CommandContext open(final int index, final CommandContext last) {
054        if (index < invokers.length) {
055    
056          //
057          final CommandInvoker invoker = invokers[index];
058          CommandContext next = open(index + 1, last);
059    
060          //
061          final Class produced = invoker.getProducedType();
062          final Class<?> consumed = next.getConsumedType();
063          boolean piped = index > 0;
064    
065          AbstractPipe filter;
066          if (consumed.equals(Chunk.class)) {
067            filter = new ToChunkPipe(produced, piped);
068          } else {
069            filter = new ConvertingPipe(produced, consumed, piped);
070          }
071          filter.open(next);
072          next = filter;
073    
074          //
075          PipeLineElement filterContext = new PipeLineElement(invoker);
076          filterContext.open(next);
077    
078          // Save current filter in field
079          // so if anything wrong happens it will be closed
080          current = filterContext;
081    
082          //
083          return filterContext;
084        } else {
085          current = last;
086          return last;
087        }
088      }
089    
090      public void provide(Void element) throws IOException {
091        throw new UnsupportedOperationException("This is not yet implemented");
092      }
093    
094      public void flush() throws IOException {
095        current.flush();
096      }
097    
098      public void close() throws IOException {
099        current.close();
100      }
101    }