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    package org.crsh.lang.impl;
020    
021    import org.crsh.lang.spi.Compiler;
022    import org.crsh.lang.spi.Language;
023    import org.crsh.lang.spi.Repl;
024    import org.crsh.plugin.CRaSHPlugin;
025    import org.crsh.plugin.PluginContext;
026    import org.crsh.shell.impl.command.ShellSession;
027    
028    import java.lang.reflect.Constructor;
029    import java.util.concurrent.atomic.AtomicReference;
030    
031    /**
032     * A command manager that is able to load a command manager via reflection.
033     *
034     * @author Julien Viet
035     */
036    public class LanguageProxy extends CRaSHPlugin<Language> implements Language {
037    
038      /** . */
039      private final AtomicReference<Language> real = new AtomicReference<Language>();
040    
041      /** . */
042      private final String name;
043    
044      /** . */
045      private final String className;
046    
047      public LanguageProxy(String name, String className) {
048        this.name = name;
049        this.className = className;
050      }
051    
052      @Override
053      public Language getImplementation() {
054        return this;
055      }
056    
057      @Override
058      public void init() {
059        try {
060          Class<Language> mgrClass = (Class<Language>)getClass().getClassLoader().loadClass(className);
061          Constructor<Language> mgrCtor = mgrClass.getConstructor(PluginContext.class);
062          Language mgr = mgrCtor.newInstance(getContext());
063          real.set(mgr);
064        }
065        catch (Exception e) {
066          log.info("Plugin is inactive");
067        }
068        catch (NoClassDefFoundError e) {
069          log.info("Plugin is inactive");
070        }
071      }
072    
073      @Override
074      public String getName() {
075        return name;
076      }
077    
078      @Override
079      public String getDisplayName() {
080        return real.get() != null ? real.get().getDisplayName() : "";
081      }
082    
083      @Override
084      public boolean isActive() {
085        return real.get() != null;
086      }
087    
088      @Override
089      public Repl getRepl() {
090        Language lang = real.get();
091        if (lang != null) {
092          return lang.getRepl();
093        } else {
094          throw new IllegalStateException(name + " language is not available");
095        }
096      }
097    
098      @Override
099      public Compiler getCompiler() {
100        Language lang = real.get();
101        if (lang != null) {
102          return lang.getCompiler();
103        } else {
104          throw new IllegalStateException(name + " language is not available");
105        }
106      }
107    
108      @Override
109      public void init(ShellSession session) {
110        Language lang = real.get();
111        if (lang != null) {
112          lang.init(session);
113        } else {
114          throw new IllegalStateException(name + " language is not available");
115        }
116      }
117    
118      @Override
119      public void destroy(ShellSession session) {
120        Language lang = real.get();
121        if (lang != null) {
122          lang.destroy(session);
123        } else {
124          throw new IllegalStateException(name + " language is not available");
125        }
126      }
127    }