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Groovy: A powerful, dynamic language for the JVM
/*
* 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.codehaus.groovy.reflection.stdclasses;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.Proxy;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import groovy.lang.Closure;
import groovy.util.ProxyGenerator;
import org.codehaus.groovy.GroovyBugError;
import org.codehaus.groovy.reflection.CachedClass;
import org.codehaus.groovy.reflection.ClassInfo;
import org.codehaus.groovy.reflection.ReflectionCache;
import org.codehaus.groovy.runtime.ConvertedClosure;
import org.codehaus.groovy.transform.trait.Traits;
public class CachedSAMClass extends CachedClass {
private static final int ABSTRACT_STATIC_PRIVATE =
Modifier.ABSTRACT|Modifier.PRIVATE|Modifier.STATIC;
private static final int VISIBILITY = 5; // public|protected
private static final Method[] EMPTY_METHOD_ARRAY = new Method[0];
private final Method method;
public CachedSAMClass(Class klazz, ClassInfo classInfo) {
super(klazz, classInfo);
method = getSAMMethod(klazz);
if (method==null) throw new GroovyBugError("assigned method should not have been null!");
}
@Override
public boolean isAssignableFrom(Class argument) {
return argument == null ||
Closure.class.isAssignableFrom(argument) ||
ReflectionCache.isAssignableFrom(getTheClass(), argument);
}
@SuppressWarnings("unchecked")
public static Object coerceToSAM(Closure argument, Method method, Class clazz, boolean isInterface) {
if (argument!=null && clazz.isAssignableFrom(argument.getClass())) {
return argument;
}
if (isInterface) {
if (Traits.isTrait(clazz)) {
Map impl = Collections.singletonMap(
method.getName(),
argument
);
return ProxyGenerator.INSTANCE.instantiateAggregate(impl,Collections.singletonList(clazz));
}
return Proxy.newProxyInstance(
clazz.getClassLoader(),
new Class[]{clazz},
new ConvertedClosure(argument));
} else {
Map m = new HashMap();
m.put(method.getName(), argument);
return ProxyGenerator.INSTANCE.
instantiateAggregateFromBaseClass(m, clazz);
}
}
@Override
public Object coerceArgument(Object argument) {
if (argument instanceof Closure) {
Class clazz = getTheClass();
return coerceToSAM((Closure) argument, method, clazz, clazz.isInterface());
} else {
return argument;
}
}
private static Method[] getDeclaredMethods(final Class c) {
try {
Method[] methods = AccessController.doPrivileged(new PrivilegedAction() {
public Method[] run() {
return c.getDeclaredMethods();
}
});
if (methods!=null) return methods;
} catch (java.security.AccessControlException ace) {
// swallow and do as if no method is available
}
return EMPTY_METHOD_ARRAY;
}
private static void getAbstractMethods(Class c, List current) {
if (c==null || !Modifier.isAbstract(c.getModifiers())) return;
getAbstractMethods(c.getSuperclass(), current);
for (Class ci : c.getInterfaces()) {
getAbstractMethods(ci, current);
}
for (Method m : getDeclaredMethods(c)) {
if (Modifier.isPrivate(m.getModifiers())) continue;
if (Modifier.isAbstract(m.getModifiers())) current.add(m);
}
}
private static boolean hasUsableImplementation(Class c, Method m) {
if (c==m.getDeclaringClass()) return false;
Method found;
try {
found = c.getMethod(m.getName(), m.getParameterTypes());
int asp = found.getModifiers() & ABSTRACT_STATIC_PRIVATE;
int visible = found.getModifiers() & VISIBILITY;
if (visible !=0 && asp == 0) return true;
} catch (NoSuchMethodException e) {/*ignore*/}
if (c==Object.class) return false;
return hasUsableImplementation(c.getSuperclass(), m);
}
private static Method getSingleNonDuplicateMethod(List current) {
if (current.isEmpty()) return null;
if (current.size()==1) return current.get(0);
Method m = current.remove(0);
for (Method m2 : current) {
if (m.getName().equals(m2.getName()) &&
Arrays.equals(m.getParameterTypes(), m2.getParameterTypes()))
{
continue;
}
return null;
}
return m;
}
/**
* returns the abstract method from a SAM type, if it is a SAM type.
* @param c the SAM class
* @return null if nothing was found, the method otherwise
*/
public static Method getSAMMethod(Class c) {
try {
return getSAMMethodImpl(c);
} catch (NoClassDefFoundError ignore) {
return null;
}
}
private static Method getSAMMethodImpl(Class c) {
// SAM = single public abstract method
// if the class is not abstract there is no abstract method
if (!Modifier.isAbstract(c.getModifiers())) return null;
if (c.isInterface()) {
Method[] methods = c.getMethods();
// res stores the first found abstract method
Method res = null;
for (Method mi : methods) {
// ignore methods, that are not abstract and from Object
if (!Modifier.isAbstract(mi.getModifiers())) continue;
// ignore trait methods which have a default implementation
if (mi.getAnnotation(Traits.Implemented.class)!=null) continue;
try {
Object.class.getMethod(mi.getName(), mi.getParameterTypes());
continue;
} catch (NoSuchMethodException e) {/*ignore*/}
// we have two methods, so no SAM
if (res!=null) return null;
res = mi;
}
return res;
} else {
LinkedList methods = new LinkedList();
getAbstractMethods(c, methods);
if (methods.isEmpty()) return null;
ListIterator it = methods.listIterator();
while (it.hasNext()) {
Method m = it.next();
if (hasUsableImplementation(c, m)) it.remove();
}
return getSingleNonDuplicateMethod(methods);
}
}
}