// Copyright 2011 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.tapestry5.internal.dynamic;
import java.util.Map;
import org.apache.tapestry5.internal.services.PageSource;
import org.apache.tapestry5.ioc.Resource;
import org.apache.tapestry5.ioc.annotations.PostInjection;
import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
import org.apache.tapestry5.ioc.internal.util.URLChangeTracker;
import org.apache.tapestry5.ioc.services.ClasspathURLConverter;
import org.apache.tapestry5.services.BindingSource;
import org.apache.tapestry5.services.UpdateListener;
import org.apache.tapestry5.services.UpdateListenerHub;
import org.apache.tapestry5.services.dynamic.DynamicTemplate;
import org.apache.tapestry5.services.dynamic.DynamicTemplateParser;
public class DynamicTemplateParserImpl implements DynamicTemplateParser, UpdateListener
{
private final Map<Resource, DynamicTemplate> cache = CollectionFactory.newConcurrentMap();
private final BindingSource bindingSource;
private final PageSource pageSource;
private final URLChangeTracker tracker;
public DynamicTemplateParserImpl(ClasspathURLConverter converter, BindingSource bindingSource, PageSource pageSource)
{
this.bindingSource = bindingSource;
this.pageSource = pageSource;
tracker = new URLChangeTracker(converter);
}
@PostInjection
public void registerAsUpdateListener(UpdateListenerHub hub)
{
hub.addUpdateListener(this);
}
public DynamicTemplate parseTemplate(Resource resource)
{
DynamicTemplate result = cache.get(resource);
if (result == null)
{
result = doParse(resource);
cache.put(resource, result);
tracker.add(resource.toURL());
}
return result;
}
private DynamicTemplate doParse(Resource resource)
{
return new DynamicTemplateSaxParser(resource, bindingSource).parse();
}
public void checkForUpdates()
{
if (tracker.containsChanges())
{
tracker.clear();
cache.clear();
// A typical case is that a "context:" or "asset:" binding is used with the Dynamic component's template
// parameter. This causes the Asset to be converted to a Resource and parsed. However, those are invariant
// bindings, so even if it is discovered that the underlying file has changed, the parsed template
// is still cached inside the component. Clearing the page pool forces the page instance to be
// rebuilt, which is a crude way of clearing out that data. Other alternatives exist, such as
// yielding up a proxy to the DynamicTemplate that is more change-aware.
pageSource.clearCache();
}
}
}