001 /*
002 * Copyright (C) 2010 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.cmdline.spi;
021
022 import org.crsh.cmdline.ParameterDescriptor;
023
024 /**
025 * A completer provides completion suffixes for a given prefix. The cmdline framework uses it when
026 * computing a completion.
027 *
028 * @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
029 * @version $Revision$
030 */
031 public interface Completer {
032
033 /**
034 * <p>Query the completer for a set of completion for the given prefix. The returned {@link ValueCompletion} object
035 * provides the possible suffixes matching the prefix argument. Each entry of the result maps to a possible
036 * completion: an entry key is the possible completion, its corresponding boolean value indicates wether the value can
037 * be further more completed or not.<p>
038 *
039 * <p>The prefix value of the completion result is optional and gives a prefix to use more than one result is provided.
040 * The interest of the prefix is to limit the size of the completion to display when they can be long, for instance
041 * a pat completion returning several values could be display in columns, however only the last name of the path would
042 * be displayed and not the entire path.</p>
043 *
044 * <p>The following guidelines should be respected:</p>
045 * <ul>
046 * <li>An empty completion means no completion can be determined, the framework will not do anything.</li>
047 * <li>A singleton map means the match was entire and the framework will complete it with the sole map entry.</li>
048 * <li>A map containing string sharing a common prefix instruct the framework to insert this common prefix.</li>
049 * <li>A list containing strings with no common prefix (other than the empty string) instruct the framework to display
050 * the list of possible completions. In that case the completion result prefix is used to preped the returned suffixes
051 * when displayed in rows.</li>
052 * <li>When a match is considered as full (the entry value is set to true), the completion should contain a trailing
053 * value that is usually a white space (but it could be a quote for quoted values).</li>
054 * </ul>
055 *
056 * <p>Example: a completer that would complete colors could</p>
057 * <ul>
058 * <li>return the result ["lack ":true,"lue ":true] with the prefix "b" for the prefix "b".</li>
059 * <li>return the result ["e ":true] with the prefix "blu" for the prefix "blu".</li>
060 * <li>return the result [] for the prefix "z".</li>
061 * </ul>
062 *
063 * <p>Example: a completer that would complete java packages could</p>
064 * <ul>
065 * <li>return the map ["ext":true,"ext.spi":false] for the prefix "java.t"</li>
066 * </ul>
067 *
068 * @param parameter the completed parameter
069 * @param prefix the prefix to complete
070 * @return the possible suffix map
071 * @throws Exception any exception that would prevent completion to perform correctly
072 */
073 ValueCompletion complete(ParameterDescriptor<?> parameter, String prefix) throws Exception;
074
075 }