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