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/*
* Copyright 2003-2007 the original author or authors.
*
* 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 groovy.lang;
import java.lang.reflect.Constructor;
import org.codehaus.groovy.runtime.GeneratedClosure;
import org.codehaus.groovy.runtime.metaclass.ClosureMetaClass;
/**
* A MetaClassRegistry is an object that is responsible for managing the a cache of MetaClass instances. Each
* java.lang.Class instance has an associated MetaClass and client code can query this interface for the MetaClass for
* a given associated java.lang.Class
*
* @see groovy.lang.MetaClass
*
* @author John Wilson
* @author Graeme Rocher
*
*/
public interface MetaClassRegistry {
/*
* The main function of the Registry
* If a Metaclass exists then return it
* otherwise create one, put it in the Registry and return it
*/
MetaClass getMetaClass(Class theClass);
/*
* Do we really want these two?
*/
void setMetaClass(Class theClass, MetaClass theMetaClass);
/**
* Removes a cached MetaClass from the registry
* @param theClass The Java class of the MetaClass to remove
*/
void removeMetaClass(Class theClass);
/**
* Retrieves the MetaClassCreationHandle that is responsible for constructing MetaClass instances
*
* @return The MetaClassCreationHandle instance
*/
MetaClassCreationHandle getMetaClassCreationHandler();
/**
* Sets the MetaClassCreationHandle instance that is responsible for constructing instances
*
* @param handle The hande instance
*/
void setMetaClassCreationHandle(MetaClassCreationHandle handle);
/**
* Class used as base for the creation of MetaClass implementations.
* The Class defaults to MetaClassImpl, if the class loading fails to
* find a special meta class. The name for such a meta class would be
* the class name it is created for with the prefix
* "groovy.runtime.metaclass." By replacing the handle in the registry
* you can have any control over the creation of what MetaClass is used
* for a class that you want to have.
* WARNING: experimental code, likely to change soon
* @author Jochen Theodorou
*/
class MetaClassCreationHandle {
public MetaClass create(Class theClass, MetaClassRegistry registry) {
try {
final Class customMetaClass = Class.forName("groovy.runtime.metaclass." + theClass.getName() + "MetaClass");
final Constructor customMetaClassConstructor = customMetaClass.getConstructor(new Class[]{MetaClassRegistry.class, Class.class});
return (MetaClass)customMetaClassConstructor.newInstance(new Object[]{registry, theClass});
} catch (final ClassNotFoundException e) {
return createNormalMetaclass(theClass, registry);
} catch (final Exception e) {
throw new GroovyRuntimeException("Could not instantiate custom Metaclass for class: " + theClass.getName() + ". Reason: " + e, e);
}
}
private MetaClass createNormalMetaclass(Class theClass,MetaClassRegistry registry) {
if (GeneratedClosure.class.isAssignableFrom(theClass)) {
return new ClosureMetaClass(registry,theClass);
} else {
return new MetaClassImpl(registry, theClass);
}
}
}
}