package net.bytebuddy.implementation.bind.annotation;
import lombok.EqualsAndHashCode;
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.implementation.Implementation;
import net.bytebuddy.implementation.auxiliary.MethodCallProxy;
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.NullConstant;
import java.lang.annotation.*;
import java.util.concurrent.Callable;
import static net.bytebuddy.matcher.ElementMatchers.named;
/**
* A parameter with this annotation is assigned a proxy 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.
*
* @see net.bytebuddy.implementation.MethodDelegation
* @see net.bytebuddy.implementation.bind.annotation.TargetMethodAnnotationDrivenBinder
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
public @interface DefaultCall {
/**
* If this parameter is not explicitly set, a parameter with the
* {@link net.bytebuddy.implementation.bind.annotation.DefaultCall} 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.
* <p> </p>
* 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 not 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;
/**
* Determines if the generated proxy should be {@link java.io.Serializable}.
*
* @return {@code true} if the generated proxy should be {@link java.io.Serializable}.
*/
boolean serializableProxy() default false;
/**
* 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 net.bytebuddy.implementation.bind.annotation.DefaultCall}
* annotation.
*
* @see TargetMethodAnnotationDrivenBinder
*/
enum Binder implements TargetMethodAnnotationDrivenBinder.ParameterBinder<DefaultCall> {
/**
* 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 serializable proxy method of the default call annotation.
*/
private static final MethodDescription.InDefinedShape SERIALIZABLE_PROXY;
/**
* 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<MethodDescription.InDefinedShape> annotationProperties = new TypeDescription.ForLoadedType(DefaultCall.class).getDeclaredMethods();
TARGET_TYPE = annotationProperties.filter(named("targetType")).getOnly();
SERIALIZABLE_PROXY = annotationProperties.filter(named("serializableProxy")).getOnly();
NULL_IF_IMPOSSIBLE = annotationProperties.filter(named("nullIfImpossible")).getOnly();
}
@Override
public Class<DefaultCall> getHandledType() {
return DefaultCall.class;
}
@Override
public MethodDelegationBinder.ParameterBinding<?> bind(AnnotationDescription.Loadable<DefaultCall> annotation,
MethodDescription source,
ParameterDescription target,
Implementation.Target implementationTarget,
Assigner assigner,
Assigner.Typing typing) {
TypeDescription targetType = target.getType().asErasure();
if (!targetType.represents(Runnable.class) && !targetType.represents(Callable.class) && !targetType.represents(Object.class)) {
throw new IllegalStateException("A default method call proxy can only be assigned to Runnable or Callable types: " + 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);
StackManipulation stackManipulation;
if (specialMethodInvocation.isValid()) {
stackManipulation = new MethodCallProxy.AssignableSignatureCall(specialMethodInvocation, annotation.getValue(SERIALIZABLE_PROXY).resolve(Boolean.class));
} else if (annotation.loadSilent().nullIfImpossible()) {
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;
@Override
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.
*/
@EqualsAndHashCode
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 DefaultCall#targetType()}.
*/
public Explicit(TypeDescription typeDescription) {
this.typeDescription = typeDescription;
}
@Override
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);
}
}
}
}
}