net.bytebuddy.implementation.bind.annotation.DefaultMethodHandle 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.TypeDescription;
import net.bytebuddy.dynamic.TargetType;
import net.bytebuddy.implementation.Implementation;
import net.bytebuddy.implementation.bind.MethodDelegationBinder;
import net.bytebuddy.implementation.bytecode.assign.Assigner;
import net.bytebuddy.implementation.bytecode.constant.NullConstant;
import net.bytebuddy.utility.JavaType;
import java.lang.annotation.*;
import static net.bytebuddy.matcher.ElementMatchers.named;
/**
* A parameter with this annotation is assigned an instance of {@code java.lang.invoke.MethodHandle} which invokes a
* default method implementation of this method. If such a method is not available, this annotation causes that this
* delegation target cannot be bound unless {@link DefaultMethodHandle#nullIfImpossible()} is set to {@code true}.
* Note that requesting such a method exposes the default method to reflective access.
*
* @see net.bytebuddy.implementation.MethodDelegation
* @see TargetMethodAnnotationDrivenBinder
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
public @interface DefaultMethodHandle {
/**
* Specifies an explicit type that declares the default method to invoke.
*
* @return The type declaring the method to invoke or {@link TargetType} to indicate that the instrumented method declared the method.
*/
Class targetType() default void.class;
/**
* Indicates that {@code null} should be assigned to this parameter if no default method is invokable.
*
* @return {@code true} if {@code null} should be assigned if no valid method can be assigned.
*/
boolean nullIfImpossible() default false;
/**
* A binder for the {@link DefaultMethodHandle} annotation.
*/
enum Binder implements TargetMethodAnnotationDrivenBinder.ParameterBinder {
/**
* The singleton instance.
*/
INSTANCE;
/**
* The {@link DefaultMethodHandle#targetType()} property.
*/
private static final MethodDescription.InDefinedShape TARGET_TYPE;
/**
* The {@link DefaultMethodHandle#nullIfImpossible()} property.
*/
private static final MethodDescription.InDefinedShape NULL_IF_IMPOSSIBLE;
/*
* Locates method constants for properties of the default method annotation.
*/
static {
MethodList methodList = TypeDescription.ForLoadedType.of(DefaultMethodHandle.class).getDeclaredMethods();
TARGET_TYPE = methodList.filter(named("targetType")).getOnly();
NULL_IF_IMPOSSIBLE = methodList.filter(named("nullIfImpossible")).getOnly();
}
/**
* {@inheritDoc}
*/
public Class getHandledType() {
return DefaultMethodHandle.class;
}
/**
* {@inheritDoc}
*/
public MethodDelegationBinder.ParameterBinding bind(final 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.isMethod()) {
TypeDescription typeDescription = annotation.getValue(TARGET_TYPE).resolve(TypeDescription.class);
Implementation.SpecialMethodInvocation specialMethodInvocation = (typeDescription.represents(void.class)
? MethodLocator.ForImplicitType.INSTANCE
: new MethodLocator.ForExplicitType(typeDescription)).resolve(implementationTarget, source).withCheckedCompatibilityTo(source.asTypeToken());
if (specialMethodInvocation.isValid()) {
return new MethodDelegationBinder.ParameterBinding.Anonymous(specialMethodInvocation.toMethodHandle().toStackManipulation());
} else if (annotation.getValue(NULL_IF_IMPOSSIBLE).resolve(Boolean.class)) {
return new MethodDelegationBinder.ParameterBinding.Anonymous(NullConstant.INSTANCE);
} else {
return MethodDelegationBinder.ParameterBinding.Illegal.INSTANCE;
}
} else if (annotation.getValue(NULL_IF_IMPOSSIBLE).resolve(Boolean.class)) {
return new MethodDelegationBinder.ParameterBinding.Anonymous(NullConstant.INSTANCE);
} else {
return MethodDelegationBinder.ParameterBinding.Illegal.INSTANCE;
}
}
/**
* A method locator is responsible for creating the super method call.
*/
protected interface MethodLocator {
/**
* Resolves the special method invocation to this target.
*
* @param implementationTarget The implementation target.
* @param source The method being instrumented.
* @return A special method invocation that represents the super call of this binding.
*/
Implementation.SpecialMethodInvocation resolve(Implementation.Target implementationTarget, MethodDescription source);
/**
* A method locator for an implicit target type.
*/
enum ForImplicitType implements MethodLocator {
/**
* The singleton instance.
*/
INSTANCE;
/**
* {@inheritDoc}
*/
public Implementation.SpecialMethodInvocation resolve(Implementation.Target implementationTarget, MethodDescription source) {
return implementationTarget.invokeDefault(source.asSignatureToken());
}
}
/**
* A method locator for an explicit target type.
*/
@HashCodeAndEqualsPlugin.Enhance
class ForExplicitType implements MethodLocator {
/**
* The explicit target type.
*/
private final TypeDescription typeDescription;
/**
* Creates a method locator for an explicit target.
*
* @param typeDescription The explicit target type.
*/
protected ForExplicitType(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(), TargetType.resolve(typeDescription, implementationTarget.getInstrumentedType()));
}
}
}
}
}