com.fitbur.bytebuddy.implementation.bind.annotation.This Maven / Gradle / Ivy
package com.fitbur.bytebuddy.implementation.bind.annotation;
import com.fitbur.bytebuddy.description.annotation.AnnotationDescription;
import com.fitbur.bytebuddy.description.method.MethodDescription;
import com.fitbur.bytebuddy.description.method.ParameterDescription;
import com.fitbur.bytebuddy.implementation.Implementation;
import com.fitbur.bytebuddy.implementation.bind.MethodDelegationBinder;
import com.fitbur.bytebuddy.implementation.bytecode.StackManipulation;
import com.fitbur.bytebuddy.implementation.bytecode.assign.Assigner;
import com.fitbur.bytebuddy.implementation.bytecode.constant.NullConstant;
import com.fitbur.bytebuddy.implementation.bytecode.member.MethodVariableAccess;
import java.lang.annotation.*;
/**
* Parameters that are annotated with this annotation will be assigned a reference to the instrumented object, if
* the instrumented method is not static. Otherwise, the method with this parameter annotation will be excluded from
* the list of possible binding candidates of the static source method.
*
* @see com.fitbur.bytebuddy.implementation.MethodDelegation
* @see com.fitbur.bytebuddy.implementation.bind.annotation.TargetMethodAnnotationDrivenBinder
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
public @interface This {
/**
* Determines if the annotated parameter should be bound to {@code null} when intercepting a {@code static} method.
*
* @return {@code true} if the annotated parameter should be bound to {@code null} as a fallback.
*/
boolean optional() default false;
/**
* A binder for handling the
* {@link com.fitbur.bytebuddy.implementation.bind.annotation.This}
* annotation.
*
* @see TargetMethodAnnotationDrivenBinder
*/
enum Binder implements TargetMethodAnnotationDrivenBinder.ParameterBinder {
/**
* The singleton instance.
*/
INSTANCE;
/**
* The index of the {@code this} reference of method variable arrays of non-static methods.
*/
private static final int THIS_REFERENCE_INDEX = 0;
@Override
public Class getHandledType() {
return This.class;
}
@Override
public MethodDelegationBinder.ParameterBinding bind(AnnotationDescription.Loadable annotation,
MethodDescription source,
ParameterDescription target,
Implementation.Target implementationTarget,
Assigner assigner) {
if (target.getType().isPrimitive()) {
throw new IllegalStateException(target + " uses a primitive type with a @This annotation");
} else if (target.getType().isArray()) {
throw new IllegalStateException(target + " uses an array type with a @This annotation");
} else if (source.isStatic() && !annotation.loadSilent().optional()) {
return MethodDelegationBinder.ParameterBinding.Illegal.INSTANCE;
}
StackManipulation assignment = source.isStatic()
? NullConstant.INSTANCE
: new StackManipulation.Compound(MethodVariableAccess.REFERENCE.loadOffset(THIS_REFERENCE_INDEX),
assigner.assign(implementationTarget.getInstrumentedType().asGenericType(), target.getType(), RuntimeType.Verifier.check(target)));
return assignment.isValid()
? new MethodDelegationBinder.ParameterBinding.Anonymous(assignment)
: MethodDelegationBinder.ParameterBinding.Illegal.INSTANCE;
}
@Override
public String toString() {
return "This.Binder." + name();
}
}
}