net.bytebuddy.implementation.bind.annotation.StubValue 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.description.annotation.AnnotationDescription;
import net.bytebuddy.description.method.MethodDescription;
import net.bytebuddy.description.method.ParameterDescription;
import net.bytebuddy.description.type.TypeDescription;
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.constant.DefaultValue;
import net.bytebuddy.implementation.bytecode.constant.NullConstant;
import java.lang.annotation.*;
/**
*
* A stub value represents the (boxed) default value of the intercepted method's return type. This value can
* only be assigned to a {@link java.lang.Object} parameter. This annotation is useful to conditionally return a
* default value from a method when using an {@link java.lang.Object} return type in combination with the
* {@link net.bytebuddy.implementation.bind.annotation.RuntimeType} annotation. The value is either representing
* {@code null} if a method returns a reference type or {@code void} or a boxed primitive of the return type
* representing the numeric value {@code 0}.
*
*
* Important: Don't confuse this annotation with {@link net.bytebuddy.asm.Advice.StubValue} annotation. This
* annotation should be used only in combination with method delegation
* ({@link net.bytebuddy.implementation.MethodDelegation MethodDelegation.to(...)}).
* For {@link net.bytebuddy.asm.Advice} ASM visitor use alternative annotation from
* net.bytebuddy.asm.Advice package.
*
*
* @see net.bytebuddy.implementation.MethodDelegation
* @see net.bytebuddy.implementation.bind.annotation.TargetMethodAnnotationDrivenBinder
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.PARAMETER})
public @interface StubValue {
/**
* Binds the {@link net.bytebuddy.implementation.bind.annotation.StubValue} annotation.
*/
enum Binder implements TargetMethodAnnotationDrivenBinder.ParameterBinder {
/**
* The singleton instance.
*/
INSTANCE;
/**
* {@inheritDoc}
*/
public Class getHandledType() {
return StubValue.class;
}
/**
* {@inheritDoc}
*/
public MethodDelegationBinder.ParameterBinding bind(AnnotationDescription.Loadable annotation,
MethodDescription source,
ParameterDescription target,
Implementation.Target implementationTarget,
Assigner assigner,
Assigner.Typing typing) {
if (!target.getType().represents(Object.class)) {
throw new IllegalStateException(target + " uses StubValue annotation on non-Object type");
}
return new MethodDelegationBinder.ParameterBinding.Anonymous(source.getReturnType().represents(void.class)
? NullConstant.INSTANCE
: new StackManipulation.Compound(DefaultValue.of(source.getReturnType().asErasure()),
assigner.assign(source.getReturnType(), TypeDescription.Generic.OBJECT, typing)));
}
}
}