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/*
* 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.tuscany.sca.contribution.resolver;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.security.AccessController;
import java.security.PrivilegedExceptionAction;
import java.util.HashMap;
import java.util.Map;
import org.apache.tuscany.sca.contribution.Contribution;
import org.apache.tuscany.sca.contribution.processor.ProcessorContext;
import org.apache.tuscany.sca.core.FactoryExtensionPoint;
/**
* An implementation of an extensible model resolver which delegates to the
* proper resolver extension based on the class of the model to resolve.
*
* @version $Rev$ $Date$
*/
public class ExtensibleModelResolver implements ModelResolver {
private final ModelResolverExtensionPoint resolverExtensions;
private final FactoryExtensionPoint modelFactories;
private final Contribution contribution;
private ModelResolver defaultResolver;
private final Map<Class<?>, ModelResolver> resolversByModelType = new HashMap<Class<?>, ModelResolver>();
private final Map<Class<?>, ModelResolver> resolversByImplementationClass = new HashMap<Class<?>, ModelResolver>();
private Map<Object, Object> map = new HashMap<Object, Object>();
private Object lastUnresolved;
/**
* Constructs an extensible model resolver
*
* @param resolverExtensions
* @param contribution
* @param modelFactories
*/
public ExtensibleModelResolver(Contribution contribution,
ModelResolverExtensionPoint resolverExtensions,
FactoryExtensionPoint modelFactories) {
this.contribution = contribution;
this.resolverExtensions = resolverExtensions;
this.modelFactories = modelFactories;
}
/**
* Returns the proper resolver instance based on the interfaces of the model
* If one is not available on the registry, instantiate on demand
*
* @param modelType
* @return
*/
public ModelResolver getModelResolverInstance(Class<?> modelType) {
// Look up a model resolver instance for the model class or
// each implemented interface
Class<?>[] interfaces = modelType.getInterfaces();
Class<?>[] classes = new Class<?>[interfaces.length + 1];
classes[0] = modelType;
if (interfaces.length != 0) {
System.arraycopy(interfaces, 0, classes, 1, interfaces.length);
}
for (Class<?> c : classes) {
// Look up an existing model resolver instance
ModelResolver resolverInstance = resolversByModelType.get(c);
if (resolverInstance != null) {
return resolverInstance;
}
// We don't have an instance, lookup a model resolver class
// and instantiate it
Class<? extends ModelResolver> resolverClass = resolverExtensions.getResolver(c);
if (resolverClass != null) {
// Construct the model resolver instance and cache it
resolverInstance = resolversByImplementationClass.get(resolverClass);
if (resolverInstance != null) {
resolversByModelType.put(c, resolverInstance);
return resolverInstance;
}
try {
final Constructor<? extends ModelResolver> constructor =
resolverClass
.getConstructor(new Class[] {Contribution.class, FactoryExtensionPoint.class});
if (constructor != null) {
resolverInstance = AccessController.doPrivileged(new PrivilegedExceptionAction<ModelResolver>() {
public ModelResolver run() throws Exception {
ModelResolver resolverInstance = constructor.newInstance(contribution, modelFactories);
return resolverInstance;
}
});
resolversByImplementationClass.put(resolverClass, resolverInstance);
resolversByModelType.put(c, resolverInstance);
return resolverInstance;
}
} catch (Exception e) {
throw new IllegalStateException(e);
}
}
}
return null;
}
public void addModel(Object resolved, ProcessorContext context) {
ModelResolver resolver = getModelResolverInstance(resolved.getClass());
if (resolver != null) {
resolver.addModel(resolved, context);
} else {
map.put(resolved, resolved);
}
}
public Object removeModel(Object resolved, ProcessorContext context) {
ModelResolver resolver = getModelResolverInstance(resolved.getClass());
if (resolver != null) {
return resolver.removeModel(resolved, context);
} else {
return map.remove(resolved);
}
}
public <T> T resolveModel(Class<T> modelClass, T unresolved, ProcessorContext context) {
// Protect against dependency cycles causing infinite recursion
// Save the current unresolved object and check later if we are trying
// to resolve the same object again
if (unresolved == lastUnresolved) {
return unresolved;
}
lastUnresolved = unresolved;
ModelResolver resolver = getModelResolverInstance(unresolved.getClass());
if (resolver != null) {
Object resolved = resolver.resolveModel(modelClass, unresolved, context);
if (resolved != null && resolved != unresolved) {
lastUnresolved = null;
return modelClass.cast(resolved);
}
} else {
//FIXME Remove this default resolver, this is currently used to resolve policy declarations
// but they should be handled by the contribution import/export mechanism instead of this
// defaultResolver hack.
if (defaultResolver != null) {
Object resolved = defaultResolver.resolveModel(modelClass, unresolved, context);
if (resolved != null && resolved != unresolved) {
lastUnresolved = null;
return modelClass.cast(resolved);
}
}
Object resolved = map.get(unresolved);
if (resolved != null) {
// Return the resolved object
lastUnresolved = null;
return modelClass.cast(resolved);
}
}
return unresolved;
}
// FIXME: TUSCANY-2499: temporarily give access to the defaultResolver to get the jms binding
// use of definitions.xml working while the definitions.xml processing is being refactored
public ModelResolver getDefaultModelResolver() {
return defaultResolver;
}
}
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