RELEASE_2_1_13/src/java/org/apache/cocoon/components/treeprocessor/sitemap/MountNode.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.cocoon.components.treeprocessor.sitemap;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import org.apache.avalon.framework.activity.Disposable;
import org.apache.avalon.framework.component.ComponentException;
import org.apache.avalon.framework.component.ComponentManager;
import org.apache.avalon.framework.component.Composable;
import org.apache.cocoon.ProcessingException;
import org.apache.cocoon.components.pipeline.ProcessingPipeline;
import org.apache.cocoon.components.treeprocessor.AbstractProcessingNode;
import org.apache.cocoon.components.treeprocessor.InvokeContext;
import org.apache.cocoon.components.treeprocessor.TreeProcessor;
import org.apache.cocoon.components.treeprocessor.variables.VariableResolver;
import org.apache.cocoon.environment.Environment;
import org.apache.commons.lang.BooleanUtils;

/**
 *
 * @author <a href="mailto:bluetkemeier@s-und-n.de">Bj&ouml;rn L&uuml;tkemeier</a>
 * @author <a href="mailto:sylvain@apache.org">Sylvain Wallez</a>
 * @version CVS $Id$
 */
public class MountNode extends AbstractProcessingNode
                       implements Composable, Disposable {

    /** The key to get the pass_through value from the Environment */
    public final static String COCOON_PASS_THROUGH = "COCOON_PASS_THROUGH";

    /** The 'uri-prefix' attribute */
    private final VariableResolver prefix;

    /** The 'src' attribute */
    private final VariableResolver source;

    /** Processors for sources */
    private Map processors = new HashMap();

    /** The processor for this node */
    private final TreeProcessor parentProcessor;

    /** The value of the 'check-reload' attribute */
    private final boolean checkReload;

    /** The component manager to be used by the mounted processor */
    private ComponentManager manager;

    /** The value of the 'pass-through' attribute */
    private final Boolean passThrough;

    public MountNode(VariableResolver prefix,
                     VariableResolver source,
                     TreeProcessor parentProcessor,
                     boolean checkReload,
                     boolean passThrough) {
        this.prefix = prefix;
        this.source = source;
        this.parentProcessor = parentProcessor;
        this.checkReload = checkReload;
        this.passThrough = BooleanUtils.toBooleanObject(passThrough);
    }

    public void compose(ComponentManager manager) throws ComponentException {
        this.manager = manager;
    }

    public final boolean invoke(Environment env, InvokeContext context)
      throws Exception {
        final Map objectModel = env.getObjectModel();

        String resolvedSource = this.source.resolve(context, objectModel);
        String resolvedPrefix = this.prefix.resolve(context, objectModel);

        if (resolvedSource.length() == 0) {
            throw new ProcessingException("Source of mount statement is empty");
        }
        TreeProcessor processor = getProcessor(resolvedSource);

        // Save context
        String oldPrefix = env.getURIPrefix();
        String oldURI    = env.getURI();
        String oldContext   = env.getContext();
        Object oldPassThrough = env.getAttribute(COCOON_PASS_THROUGH);
        env.setAttribute(COCOON_PASS_THROUGH, this.passThrough);

        boolean pipelineWasBuilt = false;

        try {
            env.changeContext(resolvedPrefix, resolvedSource);

            if (context.isBuildingPipelineOnly()) {
                // Propagate pipelines
                ProcessingPipeline pp = processor.buildPipeline(env);
                if (pp != null) {
                    context.setProcessingPipeline( pp );
                    pipelineWasBuilt = true;
                }
            } else {
                // Processor will create its own pipelines
                pipelineWasBuilt = processor.process(env);
            }
        } catch(Exception e) {
            // Wrap with our location
            throw ProcessingException.throwLocated("Sitemap: error when calling sub-sitemap", e, getLocation());

        } finally {
            // We restore the context only if no pipeline was built. This allows the pipeline
            // environment to be left unchanged when we go back to ancestor processors.
            // If no pipeline was built, we restore the context, so that the current processor
            // continues executing the sitemap in the correct environment.
            if (!pipelineWasBuilt) {
                env.setContext(oldPrefix, oldURI, oldContext);
            }

            if (oldPassThrough != null) {
                env.setAttribute(COCOON_PASS_THROUGH, oldPassThrough);
            } else {
                env.removeAttribute(COCOON_PASS_THROUGH);
            }

            // Turning recomposing as a test, according to:
            // http://marc.theaimsgroup.com/?t=106802211400005&r=1&w=2
            // Recompose pipelines which may have been recomposed by subsitemap
            // context.recompose(this.manager);
        }

        return pipelineWasBuilt;
    }

    private synchronized TreeProcessor getProcessor(String source)
    throws Exception {

        TreeProcessor processor = (TreeProcessor) processors.get(source);
        if (processor == null) {
            // Handle directory mounts
            String actualSource;
            if (source.charAt(source.length() - 1) == '/') {
                actualSource = source + "sitemap.xmap";
            } else {
                actualSource = source;
            }

            processor = this.parentProcessor.createChildProcessor(this.manager, actualSource, this.checkReload);

            // Associate to the original source
            processors.put(source, processor);
        }

        return processor;
    }

    /**
     *
     */
    public void dispose() {
        Iterator iter = this.processors.values().iterator();
        while(iter.hasNext()) {
            ((TreeProcessor)iter.next()).dispose();
        }
    }
}