tapestry/tapestry-framework/src/java/org/apache/tapestry/services/impl/TemplateSourceImpl.java - tapestry4 - Git at Google

 // Copyright 2004, 2005 The Apache Software Foundation
 //
 // Licensed 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.tapestry.services.impl;

 import edu.emory.mathcs.backport.java.util.concurrent.ConcurrentHashMap;
 import org.apache.commons.logging.Log;
 import org.apache.hivemind.ApplicationRuntimeException;
 import org.apache.hivemind.Resource;
 import org.apache.tapestry.*;
 import org.apache.tapestry.engine.ITemplateSourceDelegate;
 import org.apache.tapestry.event.ReportStatusEvent;
 import org.apache.tapestry.event.ReportStatusListener;
 import org.apache.tapestry.event.ResetEventListener;
 import org.apache.tapestry.l10n.ResourceLocalizer;
 import org.apache.tapestry.parse.*;
 import org.apache.tapestry.resolver.ComponentSpecificationResolver;
 import org.apache.tapestry.resolver.IComponentResourceResolver;
 import org.apache.tapestry.services.ComponentPropertySource;
 import org.apache.tapestry.services.TemplateSource;
 import org.apache.tapestry.spec.IComponentSpecification;
 import org.apache.tapestry.util.MultiKey;

 import java.io.BufferedInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.net.URL;
 import java.util.Iterator;
 import java.util.Locale;
 import java.util.Map;

 /**
  * Implementation of {@link org.apache.tapestry.services.TemplateSource}. Templates, once parsed,
  * stay in memory until explicitly cleared.
  *
  * @author Howard Lewis Ship
  */

 public class TemplateSourceImpl implements TemplateSource, ResetEventListener, ReportStatusListener
 {

     // The name of the component/application/etc property that will be used to
     // determine the encoding to use when loading the template

     public static final String TEMPLATE_ENCODING_PROPERTY_NAME = "org.apache.tapestry.template-encoding";

     private static final int BUFFER_SIZE = 2000;

     private String _serviceId;

     private Log _log;

     // Cache of previously retrieved templates. Key is a multi-key of
     // specification resource path and locale (local may be null), value
     // is the ComponentTemplate.

     private Map _cache = new ConcurrentHashMap();

     // Previously read templates; key is the Resource, value
     // is the ComponentTemplate.

     private Map _templates = new ConcurrentHashMap();

     private ITemplateParser _parser;

     /** @since 2.2 */

     private Resource _contextRoot;

     /** @since 3.0 */

     private ITemplateSourceDelegate _delegate;

     /** @since 4.0 */

     private ComponentSpecificationResolver _componentSpecificationResolver;

     /** @since 4.0 */

     private ComponentPropertySource _componentPropertySource;

     /** @since 4.0 */

     private ResourceLocalizer _localizer;

     /** @since 4.1.2 */

     private IComponentResourceResolver _resourceResolver;

     /**
      * Clears the template cache. This is used during debugging.
      */

     public void resetEventDidOccur()
     {
         _cache.clear();
         _templates.clear();
     }

     public void reportStatus(ReportStatusEvent event)
     {
         event.title(_serviceId);

         int templateCount = 0;
         int tokenCount = 0;
         int characterCount = 0;

         Iterator i = _templates.values().iterator();

         while (i.hasNext())
         {
             ComponentTemplate template = (ComponentTemplate) i.next();

             templateCount++;

             int count = template.getTokenCount();

             tokenCount += count;

             for (int j = 0; j < count; j++)
             {
                 TemplateToken token = template.getToken(j);

                 if (token.getType() == TokenType.TEXT)
                 {
                     TextToken tt = (TextToken) token;

                     characterCount += tt.getLength();
                 }
             }
         }

         event.property("parsed templates", templateCount);
         event.property("total template tokens", tokenCount);
         event.property("total template characters", characterCount);

         event.section("Parsed template token counts");

         i = _templates.entrySet().iterator();

         while (i.hasNext())
         {
             Map.Entry entry = (Map.Entry) i.next();

             String key = entry.getKey().toString();

             ComponentTemplate template = (ComponentTemplate) entry.getValue();

             event.property(key, template.getTokenCount());
         }
     }

     /**
      * Reads the template for the component.
      */

     public ComponentTemplate getTemplate(IRequestCycle cycle, IComponent component)
     {
         IComponentSpecification specification = component.getSpecification();
         Resource resource = specification.getSpecificationLocation();

         Locale locale = component.getPage().getLocale();

         Object key = new MultiKey(new Object[] { resource, locale }, false);

         ComponentTemplate result = searchCache(key);
         if (result != null)
             return result;

         result = findTemplate(cycle, resource, component, locale);

         if (result == null)
         {
             result = _delegate.findTemplate(cycle, component, locale);

             if (result != null)
                 return result;

             String message = component.getSpecification().isPageSpecification() ? ImplMessages
                     .noTemplateForPage(component.getExtendedId(), locale) : ImplMessages
                     .noTemplateForComponent(component.getExtendedId(), locale);

             throw new ApplicationRuntimeException(message, component, component.getLocation(), null);
         }

         saveToCache(key, result);

         return result;
     }

     private ComponentTemplate searchCache(Object key)
     {
         return (ComponentTemplate) _cache.get(key);
     }

     private void saveToCache(Object key, ComponentTemplate template)
     {
         _cache.put(key, template);

     }

     /**
      * Finds the template for the given component, using the following rules:
      * <ul>
      * <li>If the component has a $template asset, use that
      * <li>Look for a template in the same folder as the component
      * <li>If a page in the application namespace, search in the application root
      * <li>Fail!
      * </ul>
      *
      * @return the template, or null if not found
      */

     private ComponentTemplate findTemplate(IRequestCycle cycle, Resource resource,
             IComponent component, Locale locale)
     {
         IAsset templateAsset = component.getAsset(TEMPLATE_ASSET_NAME);

         if (templateAsset != null && templateAsset.getResourceLocation() != null && templateAsset.getResourceLocation().getResourceURL() != null)
             return readTemplateFromAsset(cycle, component, templateAsset.getResourceLocation());

         String name = resource.getName();
         int dotx = name.lastIndexOf('.');
         String templateExtension = getTemplateExtension(component);
         String templateBaseName = name.substring(0, dotx + 1) + templateExtension;

         ComponentTemplate result = findStandardTemplate(
                 cycle,
                 resource,
                 component,
                 templateBaseName,
                 locale);

         if (result == null && component.getSpecification().isPageSpecification()
                 && component.getNamespace().isApplicationNamespace())
             result = findPageTemplateInApplicationRoot(
                     cycle,
                     (IPage) component,
                     templateExtension,
                     locale);

         if (result == null) {

             Resource template = _resourceResolver.findComponentResource(component, cycle, null, "." + templateExtension, locale);

             if (template != null && template.getResourceURL() != null)
                 return readTemplateFromAsset(cycle, component, template);
         }

         return result;
     }

     private ComponentTemplate findPageTemplateInApplicationRoot(IRequestCycle cycle, IPage page,
             String templateExtension, Locale locale)
     {
         // Note: a subtle change from release 3.0 to 4.0.
         // In release 3.0, you could use a <page> element to define a page named Foo whose
         // specification was Bar.page. We would then search for /Bar.page. Confusing? Yes.
         // In 4.0, we are more reliant on the page name, which may include a folder prefix (i.e.,
         // "admin/EditUser", so when we search it is based on the page name and not the
         // specification resource file name. We would search for Foo.html. Moral of the
         // story is to use the page name for the page specifiation and the template.

         String templateBaseName = page.getPageName() + "." + templateExtension;

         if (_log.isDebugEnabled())
             _log.debug("Checking for " + templateBaseName + " in application root");

         Resource baseLocation = _contextRoot.getRelativeResource(templateBaseName);
         Resource localizedLocation = _localizer.findLocalization(baseLocation, locale);

         if (localizedLocation == null)
             return null;

         return getOrParseTemplate(cycle, localizedLocation, page);
     }


     /**
      * Reads an asset to get the template.
      */

     private ComponentTemplate readTemplateFromAsset(IRequestCycle cycle, IComponent component,
             Resource asset)
     {
         InputStream stream = null;

         char[] templateData = null;

         try
         {
             stream = asset.getResourceURL().openStream();

             String encoding = getTemplateEncoding(component, null);

             templateData = readTemplateStream(stream, encoding);

             stream.close();
         }
         catch (IOException ex)
         {
             throw new ApplicationRuntimeException(ImplMessages.unableToReadTemplate(asset), ex);
         }

         return constructTemplateInstance(cycle, templateData, asset, component);
     }

     /**
      * Search for the template corresponding to the resource and the locale. This may be in the
      * template map already, or may involve reading and parsing the template.
      *
      * @return the template, or null if not found.
      */

     private ComponentTemplate findStandardTemplate(IRequestCycle cycle, Resource resource,
             IComponent component, String templateBaseName, Locale locale)
     {
         if (_log.isDebugEnabled())
             _log.debug("Searching for localized version of template for " + resource
                     + " in locale " + locale.getDisplayName());

         Resource baseTemplateLocation = resource.getRelativeResource(templateBaseName);
         Resource localizedTemplateLocation = _localizer.findLocalization(baseTemplateLocation, locale);

         if (localizedTemplateLocation == null)
             return null;

         return getOrParseTemplate(cycle, localizedTemplateLocation, component);

     }

     /**
      * Returns a previously parsed template at the specified location (which must already be
      * localized). If not already in the template Map, then the location is parsed and stored into
      * the templates Map, then returned.
      */

     private ComponentTemplate getOrParseTemplate(IRequestCycle cycle, Resource resource,
             IComponent component)
     {

         ComponentTemplate result = (ComponentTemplate) _templates.get(resource);
         if (result != null)
             return result;

         // Ok, see if it exists.

         result = parseTemplate(cycle, resource, component);

         if (result != null)
             _templates.put(resource, result);

         return result;
     }

     /**
      * Reads the template for the given resource; returns null if the resource doesn't exist. Note
      * that this method is only invoked from a synchronized block, so there shouldn't be threading
      * issues here.
      */

     private ComponentTemplate parseTemplate(IRequestCycle cycle, Resource resource,
             IComponent component)
     {
         String encoding = getTemplateEncoding(component, resource.getLocale());

         char[] templateData = readTemplate(resource, encoding);
         if (templateData == null)
             return null;

         return constructTemplateInstance(cycle, templateData, resource, component);
     }

     /**
      * This method is currently synchronized, because {@link org.apache.tapestry.parse.TemplateParser} is not threadsafe.
      * Another good candidate for a pooling mechanism, especially because parsing a template may
      * take a while.
      */

     private synchronized ComponentTemplate constructTemplateInstance(IRequestCycle cycle,
             char[] templateData, Resource resource, IComponent component)
     {
         String componentAttributeName = _componentPropertySource.getComponentProperty(
                 component,
                 "org.apache.tapestry.jwcid-attribute-name");

         ITemplateParserDelegate delegate = new DefaultParserDelegate(component,
                 componentAttributeName, cycle, _componentSpecificationResolver);

         TemplateToken[] tokens;

         try
         {
             tokens = _parser.parse(templateData, delegate, resource);
         }
         catch (TemplateParseException ex)
         {
             throw new ApplicationRuntimeException(ImplMessages.unableToParseTemplate(resource), ex);
         }

         if (_log.isDebugEnabled())
             _log.debug("Parsed " + tokens.length + " tokens from template");

         return new ComponentTemplate(templateData, tokens);
     }

     /**
      * Reads the template, given the complete path to the resource. Returns null if the resource
      * doesn't exist.
      */

     private char[] readTemplate(Resource resource, String encoding)
     {
         if (_log.isDebugEnabled())
             _log.debug("Reading template " + resource);

         URL url = resource.getResourceURL();

         if (url == null)
         {
             if (_log.isDebugEnabled())
                 _log.debug("Template does not exist.");

             return null;
         }

         if (_log.isDebugEnabled())
             _log.debug("Reading template from URL " + url);

         InputStream stream = null;

         try
         {
             stream = url.openStream();

             return readTemplateStream(stream, encoding);
         }
         catch (IOException ex)
         {
             throw new ApplicationRuntimeException(ImplMessages.unableToReadTemplate(resource), ex);
         }
         finally
         {
             Tapestry.close(stream);
         }

     }

     /**
      * Reads a Stream into memory as an array of characters.
      */

     private char[] readTemplateStream(InputStream stream, String encoding) throws IOException
     {
         char[] charBuffer = new char[BUFFER_SIZE];
         StringBuffer buffer = new StringBuffer();

         InputStreamReader reader;
         if (encoding != null)
             reader = new InputStreamReader(new BufferedInputStream(stream), encoding);
         else
             reader = new InputStreamReader(new BufferedInputStream(stream));

         try
         {
             while (true)
             {
                 int charsRead = reader.read(charBuffer, 0, BUFFER_SIZE);

                 if (charsRead <= 0)
                     break;

                 buffer.append(charBuffer, 0, charsRead);
             }
         }
         finally
         {
             reader.close();
         }

         // OK, now reuse the charBuffer variable to
         // produce the final result.

         int length = buffer.length();

         charBuffer = new char[length];

         // Copy the character out of the StringBuffer and into the
         // array.

         buffer.getChars(0, length, charBuffer, 0);

         return charBuffer;
     }

     /**
      * Checks for the {@link Tapestry#TEMPLATE_EXTENSION_PROPERTY}in the component's specification,
      * then in the component's namespace's specification. Returns
      * {@link Tapestry#TEMPLATE_EXTENSION_PROPERTY} if not otherwise overriden.
      */

     private String getTemplateExtension(IComponent component)
     {
         return _componentPropertySource.getComponentProperty(
                 component,
                 Tapestry.TEMPLATE_EXTENSION_PROPERTY);
     }

     private String getTemplateEncoding(IComponent component, Locale locale)
     {
         return _componentPropertySource.getLocalizedComponentProperty(
                 component,
                 locale,
                 TEMPLATE_ENCODING_PROPERTY_NAME);
     }

     /** @since 4.0 */

     public void setParser(ITemplateParser parser)
     {
         _parser = parser;
     }

     /** @since 4.0 */

     public void setLog(Log log)
     {
         _log = log;
     }

     /** @since 4.0 */

     public void setDelegate(ITemplateSourceDelegate delegate)
     {
         _delegate = delegate;
     }

     /** @since 4.0 */

     public void setComponentSpecificationResolver(ComponentSpecificationResolver resolver)
     {
         _componentSpecificationResolver = resolver;
     }

     /** @since 4.0 */
     public void setContextRoot(Resource contextRoot)
     {
         _contextRoot = contextRoot;
     }

     /** @since 4.0 */
     public void setComponentPropertySource(ComponentPropertySource componentPropertySource)
     {
         _componentPropertySource = componentPropertySource;
     }

     /** @since 4.0 */
     public void setServiceId(String serviceId)
     {
         _serviceId = serviceId;
     }

     /** @since 4.0 */
     public void setLocalizer(ResourceLocalizer localizer)
     {
         _localizer = localizer;
     }

     public void setComponentResourceResolver(IComponentResourceResolver resourceResolver)
     {
         _resourceResolver = resourceResolver;
     }
 }
	// Copyright 2004, 2005 The Apache Software Foundation
	//
	// Licensed 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.tapestry.services.impl;

	import edu.emory.mathcs.backport.java.util.concurrent.ConcurrentHashMap;
	import org.apache.commons.logging.Log;
	import org.apache.hivemind.ApplicationRuntimeException;
	import org.apache.hivemind.Resource;
	import org.apache.tapestry.*;
	import org.apache.tapestry.engine.ITemplateSourceDelegate;
	import org.apache.tapestry.event.ReportStatusEvent;
	import org.apache.tapestry.event.ReportStatusListener;
	import org.apache.tapestry.event.ResetEventListener;
	import org.apache.tapestry.l10n.ResourceLocalizer;
	import org.apache.tapestry.parse.*;
	import org.apache.tapestry.resolver.ComponentSpecificationResolver;
	import org.apache.tapestry.resolver.IComponentResourceResolver;
	import org.apache.tapestry.services.ComponentPropertySource;
	import org.apache.tapestry.services.TemplateSource;
	import org.apache.tapestry.spec.IComponentSpecification;
	import org.apache.tapestry.util.MultiKey;

	import java.io.BufferedInputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.InputStreamReader;
	import java.net.URL;
	import java.util.Iterator;
	import java.util.Locale;
	import java.util.Map;

	/**
	* Implementation of {@link org.apache.tapestry.services.TemplateSource}. Templates, once parsed,
	* stay in memory until explicitly cleared.
	*
	* @author Howard Lewis Ship
	*/

	public class TemplateSourceImpl implements TemplateSource, ResetEventListener, ReportStatusListener
	{

	// The name of the component/application/etc property that will be used to
	// determine the encoding to use when loading the template

	public static final String TEMPLATE_ENCODING_PROPERTY_NAME = "org.apache.tapestry.template-encoding";

	private static final int BUFFER_SIZE = 2000;

	private String _serviceId;

	private Log _log;

	// Cache of previously retrieved templates. Key is a multi-key of
	// specification resource path and locale (local may be null), value
	// is the ComponentTemplate.

	private Map _cache = new ConcurrentHashMap();

	// Previously read templates; key is the Resource, value
	// is the ComponentTemplate.

	private Map _templates = new ConcurrentHashMap();

	private ITemplateParser _parser;

	/** @since 2.2 */

	private Resource _contextRoot;

	/** @since 3.0 */

	private ITemplateSourceDelegate _delegate;

	/** @since 4.0 */

	private ComponentSpecificationResolver _componentSpecificationResolver;

	/** @since 4.0 */

	private ComponentPropertySource _componentPropertySource;

	/** @since 4.0 */

	private ResourceLocalizer _localizer;

	/** @since 4.1.2 */

	private IComponentResourceResolver _resourceResolver;

	/**
	* Clears the template cache. This is used during debugging.
	*/

	public void resetEventDidOccur()
	{
	_cache.clear();
	_templates.clear();
	}

	public void reportStatus(ReportStatusEvent event)
	{
	event.title(_serviceId);

	int templateCount = 0;
	int tokenCount = 0;
	int characterCount = 0;

	Iterator i = _templates.values().iterator();

	while (i.hasNext())
	{
	ComponentTemplate template = (ComponentTemplate) i.next();

	templateCount++;

	int count = template.getTokenCount();

	tokenCount += count;

	for (int j = 0; j < count; j++)
	{
	TemplateToken token = template.getToken(j);

	if (token.getType() == TokenType.TEXT)
	{
	TextToken tt = (TextToken) token;

	characterCount += tt.getLength();
	}
	}
	}

	event.property("parsed templates", templateCount);
	event.property("total template tokens", tokenCount);
	event.property("total template characters", characterCount);

	event.section("Parsed template token counts");

	i = _templates.entrySet().iterator();

	while (i.hasNext())
	{
	Map.Entry entry = (Map.Entry) i.next();

	String key = entry.getKey().toString();

	ComponentTemplate template = (ComponentTemplate) entry.getValue();

	event.property(key, template.getTokenCount());
	}
	}

	/**
	* Reads the template for the component.
	*/

	public ComponentTemplate getTemplate(IRequestCycle cycle, IComponent component)
	{
	IComponentSpecification specification = component.getSpecification();
	Resource resource = specification.getSpecificationLocation();

	Locale locale = component.getPage().getLocale();

	Object key = new MultiKey(new Object[] { resource, locale }, false);

	ComponentTemplate result = searchCache(key);
	if (result != null)
	return result;

	result = findTemplate(cycle, resource, component, locale);

	if (result == null)
	{
	result = _delegate.findTemplate(cycle, component, locale);

	if (result != null)
	return result;

	String message = component.getSpecification().isPageSpecification() ? ImplMessages
	.noTemplateForPage(component.getExtendedId(), locale) : ImplMessages
	.noTemplateForComponent(component.getExtendedId(), locale);

	throw new ApplicationRuntimeException(message, component, component.getLocation(), null);
	}

	saveToCache(key, result);

	return result;
	}

	private ComponentTemplate searchCache(Object key)
	{
	return (ComponentTemplate) _cache.get(key);
	}

	private void saveToCache(Object key, ComponentTemplate template)
	{
	_cache.put(key, template);

	}

	/**
	* Finds the template for the given component, using the following rules:
	* <ul>
	* <li>If the component has a $template asset, use that
	* <li>Look for a template in the same folder as the component
	* <li>If a page in the application namespace, search in the application root
	* <li>Fail!
	* </ul>
	*
	* @return the template, or null if not found
	*/

	private ComponentTemplate findTemplate(IRequestCycle cycle, Resource resource,
	IComponent component, Locale locale)
	{
	IAsset templateAsset = component.getAsset(TEMPLATE_ASSET_NAME);

	if (templateAsset != null && templateAsset.getResourceLocation() != null && templateAsset.getResourceLocation().getResourceURL() != null)
	return readTemplateFromAsset(cycle, component, templateAsset.getResourceLocation());

	String name = resource.getName();
	int dotx = name.lastIndexOf('.');
	String templateExtension = getTemplateExtension(component);
	String templateBaseName = name.substring(0, dotx + 1) + templateExtension;

	ComponentTemplate result = findStandardTemplate(
	cycle,
	resource,
	component,
	templateBaseName,
	locale);

	if (result == null && component.getSpecification().isPageSpecification()
	&& component.getNamespace().isApplicationNamespace())
	result = findPageTemplateInApplicationRoot(
	cycle,
	(IPage) component,
	templateExtension,
	locale);

	if (result == null) {

	Resource template = _resourceResolver.findComponentResource(component, cycle, null, "." + templateExtension, locale);

	if (template != null && template.getResourceURL() != null)
	return readTemplateFromAsset(cycle, component, template);
	}

	return result;
	}

	private ComponentTemplate findPageTemplateInApplicationRoot(IRequestCycle cycle, IPage page,
	String templateExtension, Locale locale)
	{
	// Note: a subtle change from release 3.0 to 4.0.
	// In release 3.0, you could use a <page> element to define a page named Foo whose
	// specification was Bar.page. We would then search for /Bar.page. Confusing? Yes.
	// In 4.0, we are more reliant on the page name, which may include a folder prefix (i.e.,
	// "admin/EditUser", so when we search it is based on the page name and not the
	// specification resource file name. We would search for Foo.html. Moral of the
	// story is to use the page name for the page specifiation and the template.

	String templateBaseName = page.getPageName() + "." + templateExtension;

	if (_log.isDebugEnabled())
	_log.debug("Checking for " + templateBaseName + " in application root");

	Resource baseLocation = _contextRoot.getRelativeResource(templateBaseName);
	Resource localizedLocation = _localizer.findLocalization(baseLocation, locale);

	if (localizedLocation == null)
	return null;

	return getOrParseTemplate(cycle, localizedLocation, page);
	}



	/**
	* Reads an asset to get the template.
	*/

	private ComponentTemplate readTemplateFromAsset(IRequestCycle cycle, IComponent component,
	Resource asset)
	{
	InputStream stream = null;

	char[] templateData = null;

	try
	{
	stream = asset.getResourceURL().openStream();

	String encoding = getTemplateEncoding(component, null);

	templateData = readTemplateStream(stream, encoding);

	stream.close();
	}
	catch (IOException ex)
	{
	throw new ApplicationRuntimeException(ImplMessages.unableToReadTemplate(asset), ex);
	}

	return constructTemplateInstance(cycle, templateData, asset, component);
	}

	/**
	* Search for the template corresponding to the resource and the locale. This may be in the
	* template map already, or may involve reading and parsing the template.
	*
	* @return the template, or null if not found.
	*/

	private ComponentTemplate findStandardTemplate(IRequestCycle cycle, Resource resource,
	IComponent component, String templateBaseName, Locale locale)
	{
	if (_log.isDebugEnabled())
	_log.debug("Searching for localized version of template for " + resource
	+ " in locale " + locale.getDisplayName());

	Resource baseTemplateLocation = resource.getRelativeResource(templateBaseName);
	Resource localizedTemplateLocation = _localizer.findLocalization(baseTemplateLocation, locale);

	if (localizedTemplateLocation == null)
	return null;

	return getOrParseTemplate(cycle, localizedTemplateLocation, component);

	}

	/**
	* Returns a previously parsed template at the specified location (which must already be
	* localized). If not already in the template Map, then the location is parsed and stored into
	* the templates Map, then returned.
	*/

	private ComponentTemplate getOrParseTemplate(IRequestCycle cycle, Resource resource,
	IComponent component)
	{

	ComponentTemplate result = (ComponentTemplate) _templates.get(resource);
	if (result != null)
	return result;

	// Ok, see if it exists.

	result = parseTemplate(cycle, resource, component);

	if (result != null)
	_templates.put(resource, result);

	return result;
	}

	/**
	* Reads the template for the given resource; returns null if the resource doesn't exist. Note
	* that this method is only invoked from a synchronized block, so there shouldn't be threading
	* issues here.
	*/

	private ComponentTemplate parseTemplate(IRequestCycle cycle, Resource resource,
	IComponent component)
	{
	String encoding = getTemplateEncoding(component, resource.getLocale());

	char[] templateData = readTemplate(resource, encoding);
	if (templateData == null)
	return null;

	return constructTemplateInstance(cycle, templateData, resource, component);
	}

	/**
	* This method is currently synchronized, because {@link org.apache.tapestry.parse.TemplateParser} is not threadsafe.
	* Another good candidate for a pooling mechanism, especially because parsing a template may
	* take a while.
	*/

	private synchronized ComponentTemplate constructTemplateInstance(IRequestCycle cycle,
	char[] templateData, Resource resource, IComponent component)
	{
	String componentAttributeName = _componentPropertySource.getComponentProperty(
	component,
	"org.apache.tapestry.jwcid-attribute-name");

	ITemplateParserDelegate delegate = new DefaultParserDelegate(component,
	componentAttributeName, cycle, _componentSpecificationResolver);

	TemplateToken[] tokens;

	try
	{
	tokens = _parser.parse(templateData, delegate, resource);
	}
	catch (TemplateParseException ex)
	{
	throw new ApplicationRuntimeException(ImplMessages.unableToParseTemplate(resource), ex);
	}

	if (_log.isDebugEnabled())
	_log.debug("Parsed " + tokens.length + " tokens from template");

	return new ComponentTemplate(templateData, tokens);
	}

	/**
	* Reads the template, given the complete path to the resource. Returns null if the resource
	* doesn't exist.
	*/

	private char[] readTemplate(Resource resource, String encoding)
	{
	if (_log.isDebugEnabled())
	_log.debug("Reading template " + resource);

	URL url = resource.getResourceURL();

	if (url == null)
	{
	if (_log.isDebugEnabled())
	_log.debug("Template does not exist.");

	return null;
	}

	if (_log.isDebugEnabled())
	_log.debug("Reading template from URL " + url);

	InputStream stream = null;

	try
	{
	stream = url.openStream();

	return readTemplateStream(stream, encoding);
	}
	catch (IOException ex)
	{
	throw new ApplicationRuntimeException(ImplMessages.unableToReadTemplate(resource), ex);
	}
	finally
	{
	Tapestry.close(stream);
	}

	}

	/**
	* Reads a Stream into memory as an array of characters.
	*/

	private char[] readTemplateStream(InputStream stream, String encoding) throws IOException
	{
	char[] charBuffer = new char[BUFFER_SIZE];
	StringBuffer buffer = new StringBuffer();

	InputStreamReader reader;
	if (encoding != null)
	reader = new InputStreamReader(new BufferedInputStream(stream), encoding);
	else
	reader = new InputStreamReader(new BufferedInputStream(stream));

	try
	{
	while (true)
	{
	int charsRead = reader.read(charBuffer, 0, BUFFER_SIZE);

	if (charsRead <= 0)
	break;

	buffer.append(charBuffer, 0, charsRead);
	}
	}
	finally
	{
	reader.close();
	}

	// OK, now reuse the charBuffer variable to
	// produce the final result.

	int length = buffer.length();

	charBuffer = new char[length];

	// Copy the character out of the StringBuffer and into the
	// array.

	buffer.getChars(0, length, charBuffer, 0);

	return charBuffer;
	}

	/**
	* Checks for the {@link Tapestry#TEMPLATE_EXTENSION_PROPERTY}in the component's specification,
	* then in the component's namespace's specification. Returns
	* {@link Tapestry#TEMPLATE_EXTENSION_PROPERTY} if not otherwise overriden.
	*/

	private String getTemplateExtension(IComponent component)
	{
	return _componentPropertySource.getComponentProperty(
	component,
	Tapestry.TEMPLATE_EXTENSION_PROPERTY);
	}

	private String getTemplateEncoding(IComponent component, Locale locale)
	{
	return _componentPropertySource.getLocalizedComponentProperty(
	component,
	locale,
	TEMPLATE_ENCODING_PROPERTY_NAME);
	}

	/** @since 4.0 */

	public void setParser(ITemplateParser parser)
	{
	_parser = parser;
	}

	/** @since 4.0 */

	public void setLog(Log log)
	{
	_log = log;
	}

	/** @since 4.0 */

	public void setDelegate(ITemplateSourceDelegate delegate)
	{
	_delegate = delegate;
	}

	/** @since 4.0 */

	public void setComponentSpecificationResolver(ComponentSpecificationResolver resolver)
	{
	_componentSpecificationResolver = resolver;
	}

	/** @since 4.0 */
	public void setContextRoot(Resource contextRoot)
	{
	_contextRoot = contextRoot;
	}

	/** @since 4.0 */
	public void setComponentPropertySource(ComponentPropertySource componentPropertySource)
	{
	_componentPropertySource = componentPropertySource;
	}

	/** @since 4.0 */
	public void setServiceId(String serviceId)
	{
	_serviceId = serviceId;
	}

	/** @since 4.0 */
	public void setLocalizer(ResourceLocalizer localizer)
	{
	_localizer = localizer;
	}

	public void setComponentResourceResolver(IComponentResourceResolver resourceResolver)
	{
	_resourceResolver = resourceResolver;
	}
	}