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.TypeProxy;
import net.bytebuddy.implementation.bind.MethodDelegationBinder;
import net.bytebuddy.implementation.bytecode.assign.Assigner;
import java.lang.annotation.*;
import static net.bytebuddy.matcher.ElementMatchers.named;
/**
* Parameters that are annotated with this annotation are assigned an instance of an auxiliary proxy type that allows calling
* any default method of an interface of the instrumented type where the parameter type must be an interface that is
* directly implemented by the instrumented type. The generated proxy will directly implement the parameter's
* interface. If the interface of the annotation is not implemented by the instrumented type, the method with this
* parameter is not considered as a binding target.
*
* @see net.bytebuddy.implementation.MethodDelegation
* @see net.bytebuddy.implementation.bind.annotation.TargetMethodAnnotationDrivenBinder
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
public @interface Default {
/**
* Determines if the generated proxy should be {@link java.io.Serializable}. If the annotated type
* already is serializable, such an explicit specification is not required.
*
* @return {@code true} if the generated proxy should be {@link java.io.Serializable}.
*/
boolean serializableProxy() default false;
/**
* Determines the type that is implemented by the proxy. When this value is set to its default value
* {@code void}, the proxy is created as an instance of the parameter's type. It is <b>not</b> possible to
* set the value of this property to {@link net.bytebuddy.dynamic.TargetType} as a interface cannot implement itself.
*
* @return The type of the proxy or an indicator type, i.e. {@code void}.
*/
Class<?> proxyType() default void.class;
/**
* A binder for the {@link net.bytebuddy.implementation.bind.annotation.Default} annotation.
*/
enum Binder implements TargetMethodAnnotationDrivenBinder.ParameterBinder<Default> {
/**
* The singleton instance.
*/
INSTANCE;
/**
* A method reference to the serializable proxy property.
*/
private static final MethodDescription.InDefinedShape SERIALIZABLE_PROXY;
/**
* A method reference to the proxy type property.
*/
private static final MethodDescription.InDefinedShape PROXY_TYPE;
/*
* Extracts method references of the default annotation.
*/
static {
MethodList<MethodDescription.InDefinedShape> annotationProperties = new TypeDescription.ForLoadedType(Default.class).getDeclaredMethods();
SERIALIZABLE_PROXY = annotationProperties.filter(named("serializableProxy")).getOnly();
PROXY_TYPE = annotationProperties.filter(named("proxyType")).getOnly();
}
@Override
public Class<Default> getHandledType() {
return Default.class;
}
@Override
public MethodDelegationBinder.ParameterBinding<?> bind(AnnotationDescription.Loadable<Default> annotation,
MethodDescription source,
ParameterDescription target,
Implementation.Target implementationTarget,
Assigner assigner,
Assigner.Typing typing) {
TypeDescription proxyType = TypeLocator.ForType.of(annotation.getValue(PROXY_TYPE).resolve(TypeDescription.class)).resolve(target.getType());
if (!proxyType.isInterface()) {
throw new IllegalStateException(target + " uses the @Default annotation on an invalid type");
}
if (source.isStatic() || !implementationTarget.getInstrumentedType().getInterfaces().asErasures().contains(proxyType)) {
return MethodDelegationBinder.ParameterBinding.Illegal.INSTANCE;
} else {
return new MethodDelegationBinder.ParameterBinding.Anonymous(new TypeProxy.ForDefaultMethod(proxyType,
implementationTarget,
annotation.getValue(SERIALIZABLE_PROXY).resolve(Boolean.class)));
}
}
/**
* Locates the type which should be the base type of the created proxy.
*/
protected interface TypeLocator {
/**
* Resolves the target type.
*
* @param parameterType The type of the target parameter.
* @return The proxy type.
*/
TypeDescription resolve(TypeDescription.Generic parameterType);
/**
* A type locator that yields the target parameter's type.
*/
enum ForParameterType implements TypeLocator {
/**
* The singleton instance.
*/
INSTANCE;
@Override
public TypeDescription resolve(TypeDescription.Generic parameterType) {
return parameterType.asErasure();
}
}
/**
* A type locator that returns a given type.
*/
@EqualsAndHashCode
class ForType implements TypeLocator {
/**
* The type to be returned upon resolution.
*/
private final TypeDescription typeDescription;
/**
* Creates a new type locator for a given type.
*
* @param typeDescription The type to be returned upon resolution.
*/
protected ForType(TypeDescription typeDescription) {
this.typeDescription = typeDescription;
}
/**
* Resolves a type locator based upon an annotation value.
*
* @param typeDescription The annotation's value.
* @return The appropriate type locator.
*/
protected static TypeLocator of(TypeDescription typeDescription) {
if (typeDescription.represents(void.class)) {
return ForParameterType.INSTANCE;
} else if (!typeDescription.isInterface()) {
throw new IllegalStateException("Cannot assign proxy to " + typeDescription);
} else {
return new ForType(typeDescription);
}
}
@Override
public TypeDescription resolve(TypeDescription.Generic parameterType) {
if (!typeDescription.isAssignableTo(parameterType.asErasure())) {
throw new IllegalStateException("Impossible to assign " + typeDescription + " to parameter of type " + parameterType);
}
return typeDescription;
}
}
}
}
}