src/main/java/freemarker/debug/impl/DebuggerService.java

/*
 * Copyright (c) 2003 The Visigoth Software Society. All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Visigoth Software Society (http://www.visigoths.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the 
 *    project contributors may be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact visigoths@visigoths.org.
 *
 * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
 *    nor may "FreeMarker" or "Visigoth" appear in their names
 *    without prior written permission of the Visigoth Software Society.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Visigoth Software Society. For more
 * information on the Visigoth Software Society, please see
 * http://www.visigoths.org/
 */

package freemarker.debug.impl;

import java.rmi.RemoteException;
import java.util.Collections;
import java.util.List;

import freemarker.core.Environment;
import freemarker.template.Template;
import freemarker.template.utility.SecurityUtilities;

/**
 * This class provides debugging hooks for the core FreeMarker engine. It is
 * not usable for anyone outside the FreeMarker core classes. It is public only
 * as an implementation detail.
 * @author Attila Szegedi
 */
public abstract class DebuggerService
{
    private static final DebuggerService instance = createInstance();
    
    private static DebuggerService createInstance()
    {
        // Creates the appropriate service class. If the debugging is turned
        // off, this is a fast no-op service, otherwise it's the real-thing
        // RMI service.
        return 
            SecurityUtilities.getSystemProperty("freemarker.debug.password") == null
            ? (DebuggerService)new NoOpDebuggerService()
            : (DebuggerService)new RmiDebuggerService();
    }

    public static List getBreakpoints(String templateName)
    {
        return instance.getBreakpointsSpi(templateName);
    }
    
    abstract List getBreakpointsSpi(String templateName);

    public static void registerTemplate(Template template)
    {
        instance.registerTemplateSpi(template);
    }
    
    abstract void registerTemplateSpi(Template template);
    
    public static boolean suspendEnvironment(Environment env, String templateName, int line)
    throws
        RemoteException
    {
        return instance.suspendEnvironmentSpi(env, templateName, line);
    }
    
    abstract boolean suspendEnvironmentSpi(Environment env, String templateName, int line)
    throws
        RemoteException;

    abstract void shutdownSpi();

    public static void shutdown()
    {
        instance.shutdownSpi();
    }

    private static class NoOpDebuggerService extends DebuggerService
    {
        List getBreakpointsSpi(String templateName)
        {
            return Collections.EMPTY_LIST;
        }
        
        boolean suspendEnvironmentSpi(Environment env, String templateName, int line)
        {
            throw new UnsupportedOperationException();
        }
        
        void registerTemplateSpi(Template template)
        {
        }

        void shutdownSpi()
        {
        }
    }
}