001    /*
002     * Copyright (C) 2003-2009 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.ShellPrintWriter;
023    
024    /**
025     * The invocation context provided to a command during the invocation phase.
026     * It provides the various interactions that a command can perform with
027     * its context during its invocation.
028     *
029     * @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
030     * @version $Revision$
031     */
032    public interface InvocationContext<C, P> extends CommandContext {
033    
034      /**
035       * Returns the term width in chars. When the value is not positive it means
036       * the value could not be determined.
037       *
038       * @return the term width
039       */
040      int getWidth();
041    
042      /**
043       * Returns a generic property, usually this property is resolved by the
044       * shell client.
045       *
046       * @param propertyName the property name
047       * @return the property value
048       */
049      String getProperty(String propertyName);
050    
051      /**
052       * Display a message and read a line on the console. If no line can be read
053       * then null is returned.
054       *
055       * @param msg the message to display before reading a line
056       * @param echo wether or not the line read should be echoed when typing
057       * @return the line read
058       */
059      String readLine(String msg, boolean echo);
060    
061      /**
062       * Returns the writer for the output.
063       *
064       * @return the writer
065       */
066      ShellPrintWriter getWriter();
067    
068      /**
069       * Returns true if the command is involved in a pipe operation and receives
070       * a stream.
071       *
072       * @return true if the command is involved in a pipe
073       */
074      boolean isPiped();
075    
076      /**
077       * Returns an iterator over the stream of consumed items.
078       *
079       * @return the consumed items
080       * @throws IllegalStateException if the command is not involved in a
081       *                               pipe operation
082       */
083      Iterable<C> consume() throws IllegalStateException;
084    
085      /**
086       * Produce an item.
087       *
088       * @param product the item product
089       */
090      void produce(P product);
091    
092    }