001    /*
002     * SonarQube, open source software quality management tool.
003     * Copyright (C) 2008-2014 SonarSource
004     * mailto:contact AT sonarsource DOT com
005     *
006     * SonarQube is free software; you can redistribute it and/or
007     * modify it under the terms of the GNU Lesser General Public
008     * License as published by the Free Software Foundation; either
009     * version 3 of the License, or (at your option) any later version.
010     *
011     * SonarQube is distributed in the hope that it will be useful,
012     * but WITHOUT ANY WARRANTY; without even the implied warranty of
013     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014     * Lesser General Public License for more details.
015     *
016     * You should have received a copy of the GNU Lesser General Public License
017     * along with this program; if not, write to the Free Software Foundation,
018     * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
019     */
020    package org.sonar.api;
021    
022    /**
023     * Factory of extensions. It allows to dynamically create extensions depending upon runtime context. A use-case is
024     * to create one rule repository by language.
025     *
026     * <p>Notes :
027     * <ul>
028     * <li>the provider is declared in Plugin.getExtensions()</li>
029     * <li>the provider must also implement ServerExtension and/or BatchExtension</li>
030     * <li>the provider can accept dependencies (parameters) in its constructors.</li>
031     * <li>the method provide() is executed once by sonar</li>
032     * <li>the method provide() must return an object, a class or an Iterable of objects. <strong>Arrays are excluded</strong>.</li>
033     * </ul>
034     * </p>
035     *
036     * <p>Example:
037     * <pre>
038     * public class RuleRepositoryProvider extends ExtensionProvider implements ServerExtension {
039     *   private Language[] languages;
040     *
041     *   public RuleRepositoryProvider(Language[] languages) {
042     *     this.languages = languages;
043     *   }
044     *
045     *   public List<RuleRepository> provide() {
046     *     List<RuleRepository> result = new ArrayList<RuleRepository>();
047     *     for(Language language: languages) {
048     *       result.add(new RuleRepository(..., language, ...));
049     *     }
050     *     return result;
051     *   }
052     * }
053     * </pre>
054     * </p>
055     *
056     * @since 2.3
057     */
058    public abstract class ExtensionProvider implements Extension {
059    
060      public abstract Object provide();
061    }