net.bytebuddy.implementation.bind.annotation.DefaultCallHandle Maven / Gradle / Ivy
/*
* Copyright 2014 - Present Rafael Winterhalter
*
* 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 net.bytebuddy.implementation.bind.annotation;
import net.bytebuddy.build.HashCodeAndEqualsPlugin;
import net.bytebuddy.description.annotation.AnnotationDescription;
import net.bytebuddy.description.method.MethodDescription;
import net.bytebuddy.description.method.MethodList;
import net.bytebuddy.description.method.ParameterDescription;
import net.bytebuddy.description.type.TypeDefinition;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.description.type.TypeList;
import net.bytebuddy.implementation.Implementation;
import net.bytebuddy.implementation.bind.MethodDelegationBinder;
import net.bytebuddy.implementation.bytecode.StackManipulation;
import net.bytebuddy.implementation.bytecode.assign.Assigner;
import net.bytebuddy.implementation.bytecode.collection.ArrayFactory;
import net.bytebuddy.implementation.bytecode.constant.IntegerConstant;
import net.bytebuddy.implementation.bytecode.constant.NullConstant;
import net.bytebuddy.implementation.bytecode.member.MethodInvocation;
import net.bytebuddy.implementation.bytecode.member.MethodVariableAccess;
import net.bytebuddy.utility.JavaType;
import org.objectweb.asm.Opcodes;
import java.lang.annotation.*;
import java.util.ArrayList;
import java.util.List;
import static net.bytebuddy.matcher.ElementMatchers.named;
/**
* A parameter with this annotation is assigned a method handle for invoking a default method that fits the intercepted method.
* If no suitable default method for the intercepted method can be identified, the target method with the annotated
* parameter is considered to be unbindable, unless a {@code null} value is requested by setting a property.
*
* @see net.bytebuddy.implementation.MethodDelegation
* @see TargetMethodAnnotationDrivenBinder
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
public @interface DefaultCallHandle {
/**
* If this parameter is not explicitly set, a parameter with the {@link DefaultCallHandle} is only bound to a
* source method if this source method directly represents an unambiguous, invokable default method. On the other
* hand, if a method is not defined unambiguously by an interface, not setting this parameter will exclude
* the target method with the annotated parameter from a binding to the source method.
*
* If this parameter is however set to an explicit interface type, a default method is always invoked on this given
* type as long as this type defines a method with a compatible signature. If this is not the case, the target
* method with the annotated parameter is no longer considered as a possible binding candidate of a source method.
*
* @return The target interface that a default method invocation is to be defined upon. If no such explicit target
* is set, this parameter should not be defined as the predefined {@code void} type encodes an implicit resolution.
*/
Class targetType() default void.class;
/**
* Assigns {@code null} to the parameter if it is impossible to invoke the super method or a possible dominant default method, if permitted.
*
* @return {@code true} if a {@code null} constant should be assigned to this parameter in case that a legal binding is impossible.
*/
boolean nullIfImpossible() default false;
/**
* A binder for handling the {@link DefaultCallHandle} annotation.
*
* @see TargetMethodAnnotationDrivenBinder
*/
enum Binder implements TargetMethodAnnotationDrivenBinder.ParameterBinder {
/**
* The singleton instance.
*/
INSTANCE;
/**
* A reference to the target type method of the default call annotation.
*/
private static final MethodDescription.InDefinedShape TARGET_TYPE;
/**
* A reference to the null if possible method of the default call annotation.
*/
private static final MethodDescription.InDefinedShape NULL_IF_IMPOSSIBLE;
/*
* Looks up method constants of the default call annotation.
*/
static {
MethodList annotationProperties = TypeDescription.ForLoadedType.of(DefaultCallHandle.class).getDeclaredMethods();
TARGET_TYPE = annotationProperties.filter(named("targetType")).getOnly();
NULL_IF_IMPOSSIBLE = annotationProperties.filter(named("nullIfImpossible")).getOnly();
}
/**
* {@inheritDoc}
*/
public Class getHandledType() {
return DefaultCallHandle.class;
}
/**
* {@inheritDoc}
*/
public MethodDelegationBinder.ParameterBinding bind(AnnotationDescription.Loadable annotation,
MethodDescription source,
ParameterDescription target,
Implementation.Target implementationTarget,
Assigner assigner,
Assigner.Typing typing) {
if (!target.getType().asErasure().isAssignableFrom(JavaType.METHOD_HANDLE.getTypeStub())) {
throw new IllegalStateException("Cannot assign MethodHandle type to " + target);
} else if (source.isConstructor()) {
return annotation.getValue(NULL_IF_IMPOSSIBLE).resolve(Boolean.class)
? new MethodDelegationBinder.ParameterBinding.Anonymous(NullConstant.INSTANCE)
: MethodDelegationBinder.ParameterBinding.Illegal.INSTANCE;
}
TypeDescription typeDescription = annotation.getValue(TARGET_TYPE).resolve(TypeDescription.class);
Implementation.SpecialMethodInvocation specialMethodInvocation = (typeDescription.represents(void.class)
? DefaultMethodLocator.Implicit.INSTANCE
: new DefaultMethodLocator.Explicit(typeDescription)).resolve(implementationTarget, source).withCheckedCompatibilityTo(source.asTypeToken());
StackManipulation stackManipulation;
if (specialMethodInvocation.isValid()) {
List stackManipulations = new ArrayList(3 + source.getParameters().size() * 3);
stackManipulations.add(specialMethodInvocation.toMethodHandle().toStackManipulation());
stackManipulations.add(MethodVariableAccess.loadThis());
stackManipulations.add(MethodInvocation.invoke(new MethodDescription.Latent(JavaType.METHOD_HANDLE.getTypeStub(), new MethodDescription.Token("bindTo",
Opcodes.ACC_PUBLIC,
JavaType.METHOD_HANDLE.getTypeStub().asGenericType(),
new TypeList.Generic.Explicit(TypeDefinition.Sort.describe(Object.class))))));
if (!source.getParameters().isEmpty()) {
List values = new ArrayList(source.getParameters().size());
for (ParameterDescription parameterDescription : source.getParameters()) {
values.add(parameterDescription.getType().isPrimitive() ? new StackManipulation.Compound(MethodVariableAccess.load(parameterDescription), assigner.assign(parameterDescription.getType(),
parameterDescription.getType().asErasure().asBoxed().asGenericType(),
typing)) : MethodVariableAccess.load(parameterDescription));
}
stackManipulations.add(IntegerConstant.forValue(0));
stackManipulations.add(ArrayFactory.forType(TypeDescription.ForLoadedType.of(Object.class).asGenericType()).withValues(values));
stackManipulations.add(MethodInvocation.invoke(new MethodDescription.Latent(JavaType.METHOD_HANDLES.getTypeStub(), new MethodDescription.Token("insertArguments",
Opcodes.ACC_PUBLIC | Opcodes.ACC_STATIC,
JavaType.METHOD_HANDLE.getTypeStub().asGenericType(),
new TypeList.Generic.Explicit(JavaType.METHOD_HANDLE.getTypeStub(), TypeDefinition.Sort.describe(int.class), TypeDefinition.Sort.describe(Object[].class))))));
}
stackManipulation = new StackManipulation.Compound(stackManipulations);
} else if (annotation.getValue(NULL_IF_IMPOSSIBLE).resolve(Boolean.class)) {
stackManipulation = NullConstant.INSTANCE;
} else {
return MethodDelegationBinder.ParameterBinding.Illegal.INSTANCE;
}
return new MethodDelegationBinder.ParameterBinding.Anonymous(stackManipulation);
}
/**
* A default method locator is responsible for looking up a default method to a given source method.
*/
protected interface DefaultMethodLocator {
/**
* Locates the correct default method to a given source method.
*
* @param implementationTarget The current implementation target.
* @param source The source method for which a default method should be looked up.
* @return A special method invocation of the default method or an illegal special method invocation,
* if no suitable invocation could be located.
*/
Implementation.SpecialMethodInvocation resolve(Implementation.Target implementationTarget, MethodDescription source);
/**
* An implicit default method locator that only permits the invocation of a default method if the source
* method itself represents a method that was defined on a default method interface.
*/
enum Implicit implements DefaultMethodLocator {
/**
* The singleton instance.
*/
INSTANCE;
/**
* {@inheritDoc}
*/
public Implementation.SpecialMethodInvocation resolve(Implementation.Target implementationTarget, MethodDescription source) {
return implementationTarget.invokeDefault(source.asSignatureToken());
}
}
/**
* An explicit default method locator attempts to look up a default method in the specified interface type.
*/
@HashCodeAndEqualsPlugin.Enhance
class Explicit implements DefaultMethodLocator {
/**
* A description of the type on which the default method should be invoked.
*/
private final TypeDescription typeDescription;
/**
* Creates a new explicit default method locator.
*
* @param typeDescription The actual target interface as explicitly defined by
* {@link DefaultCallHandle#targetType()}.
*/
public Explicit(TypeDescription typeDescription) {
this.typeDescription = typeDescription;
}
/**
* {@inheritDoc}
*/
public Implementation.SpecialMethodInvocation resolve(Implementation.Target implementationTarget, MethodDescription source) {
if (!typeDescription.isInterface()) {
throw new IllegalStateException(source + " method carries default method call parameter on non-interface type");
}
return implementationTarget.invokeDefault(source.asSignatureToken(), typeDescription);
}
}
}
}
}