com.fitbur.bytebuddy.implementation.bind.annotation.Super Maven / Gradle / Ivy
package com.fitbur.bytebuddy.implementation.bind.annotation;
import com.fitbur.bytebuddy.description.annotation.AnnotationDescription;
import com.fitbur.bytebuddy.description.enumeration.EnumerationDescription;
import com.fitbur.bytebuddy.description.method.MethodDescription;
import com.fitbur.bytebuddy.description.method.MethodList;
import com.fitbur.bytebuddy.description.method.ParameterDescription;
import com.fitbur.bytebuddy.description.type.TypeDescription;
import com.fitbur.bytebuddy.dynamic.TargetType;
import com.fitbur.bytebuddy.implementation.Implementation;
import com.fitbur.bytebuddy.implementation.auxiliary.TypeProxy;
import com.fitbur.bytebuddy.implementation.bind.MethodDelegationBinder;
import com.fitbur.bytebuddy.implementation.bytecode.StackManipulation;
import com.fitbur.bytebuddy.implementation.bytecode.assign.Assigner;
import java.lang.annotation.*;
import java.util.Arrays;
import static com.fitbur.bytebuddy.matcher.ElementMatchers.named;
/**
* Parameters that are annotated with this annotation are assigned an instance of an auxiliary proxy type that allows calling
* any {@code super} methods of the instrumented type where the parameter type must be a super type of the instrumented type.
* The proxy type will be a direct subclass of the parameter's type such as for example a specific interface.
*
* Obviously, the proxy type must be instantiated before it is assigned to the intercepting method's parameter. For this
* purpose, two strategies are available which can be specified by setting the {@link Super#strategy()} parameter which can
* be assigned:
*
* - {@link com.fitbur.bytebuddy.implementation.bind.annotation.Super.Instantiation#CONSTRUCTOR}:
* A constructor call is made where {@link Super#constructorParameters()} determines the constructor's signature. Any constructor
* parameter is assigned the parameter's default value when the constructor is called. Calling the default constructor is the
* preconfigured strategy.
* - {@link com.fitbur.bytebuddy.implementation.bind.annotation.Super.Instantiation#UNSAFE}:
* The proxy is created by making use of Java's {@link sun.reflect.ReflectionFactory} which is however not a public API which
* is why it should be used with care. No constructor is called when this strategy is used. If this option is set, the
* {@link Super#constructorParameters()} parameter is ignored.
*
* Note that when for example intercepting a type {@code Foo} that implements some interface {@code Bar}, the proxy type
* will only implement {@code Bar} and therefore extend {@link java.lang.Object} what allows for calling the default
* constructor on the proxy. This implies that an interception by some method {@code qux(@Super Baz baz, @Super Bar bar)}
* would cause the creation of two super call proxies, one extending {@code Baz}, the other extending {@code Bar}, give
* that both types are super types of {@code Foo}.
*
* As an exception, no method calls to {@link Object#finalize()} are delegated by calling this method on the {@code super}-call
* proxy by default. If this is absolutely necessary, this can however be enabled by setting {@link Super#ignoreFinalizer()}
* to {@code false}.
*
* If a method parameter is not a super type of the instrumented type, the method with the parameter that is annoted by
* #{@code Super} is not considered a possible delegation target.
*
* @see com.fitbur.bytebuddy.implementation.MethodDelegation
* @see com.fitbur.bytebuddy.implementation.bind.annotation.TargetMethodAnnotationDrivenBinder
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
public @interface Super {
/**
* Determines how the {@code super}call proxy type is instantiated.
*
* @return The instantiation strategy for this proxy.
*/
Instantiation strategy() default Instantiation.CONSTRUCTOR;
/**
* If {@code true}, the proxy type will not implement {@code super} calls to {@link Object#finalize()} or any overridden methods.
*
* @return {@code false} if finalizer methods should be considered for {@code super}-call proxy type delegation.
*/
boolean ignoreFinalizer() default true;
/**
* 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;
/**
* Defines the parameter types of the constructor to be called for the created {@code super}-call proxy type.
*
* @return The parameter types of the constructor to be called.
*/
Class[] constructorParameters() default {};
/**
* 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. When it is set to
* {@link TargetType}, it is created as an instance of the generated class. Otherwise, the proxy type
* is set to the given value.
*
* @return The type of the proxy or an indicator type, i.e. {@code void} or {@link TargetType}.
*/
Class proxyType() default void.class;
/**
* Determines the instantiation of the proxy type.
*
* @see com.fitbur.bytebuddy.implementation.bind.annotation.Super
*/
enum Instantiation {
/**
* A proxy instance is instantiated by its constructor. For the constructor's arguments, the parameters default
* values are used. The constructor can be identified by setting {@link Super#constructorParameters()}.
*/
CONSTRUCTOR {
@Override
protected StackManipulation proxyFor(TypeDescription parameterType,
Implementation.Target implementationTarget,
AnnotationDescription.Loadable annotation) {
return new TypeProxy.ForSuperMethodByConstructor(parameterType,
implementationTarget,
Arrays.asList(annotation.getValue(CONSTRUCTOR_PARAMETERS, TypeDescription[].class)),
annotation.getValue(IGNORE_FINALIZER, Boolean.class),
annotation.getValue(SERIALIZABLE_PROXY, Boolean.class));
}
},
/**
* A proxy is instantiated by calling JVM internal methods and without calling a constructor. This strategy
* might fail on exotic JVM implementations.
*/
UNSAFE {
@Override
protected StackManipulation proxyFor(TypeDescription parameterType,
Implementation.Target implementationTarget,
AnnotationDescription.Loadable annotation) {
return new TypeProxy.ForSuperMethodByReflectionFactory(parameterType,
implementationTarget,
annotation.getValue(IGNORE_FINALIZER, Boolean.class),
annotation.getValue(SERIALIZABLE_PROXY, Boolean.class));
}
};
/**
* A reference to the ignore finalizer method.
*/
private static final MethodDescription.InDefinedShape IGNORE_FINALIZER;
/**
* A reference to the serializable proxy method.
*/
private static final MethodDescription.InDefinedShape SERIALIZABLE_PROXY;
/**
* A reference to the constructor parameters method.
*/
private static final MethodDescription.InDefinedShape CONSTRUCTOR_PARAMETERS;
/*
* Extracts method references to the annotation methods.
*/
static {
MethodList annotationProperties = new TypeDescription.ForLoadedType(Super.class).getDeclaredMethods();
IGNORE_FINALIZER = annotationProperties.filter(named("ignoreFinalizer")).getOnly();
SERIALIZABLE_PROXY = annotationProperties.filter(named("serializableProxy")).getOnly();
CONSTRUCTOR_PARAMETERS = annotationProperties.filter(named("constructorParameters")).getOnly();
}
/**
* Creates a stack manipulation which loads a {@code super}-call proxy onto the stack.
*
* @param parameterType The type of the parameter that was annotated with
* {@link com.fitbur.bytebuddy.implementation.bind.annotation.Super}
* @param implementationTarget The implementation target for the currently created type.
* @param annotation The annotation that caused this method call.
* @return A stack manipulation representing this instance's instantiation strategy.
*/
protected abstract StackManipulation proxyFor(TypeDescription parameterType,
Implementation.Target implementationTarget,
AnnotationDescription.Loadable annotation);
@Override
public String toString() {
return "Super.Instantiation." + name();
}
}
/**
* A binder for handling the
* {@link com.fitbur.bytebuddy.implementation.bind.annotation.Super}
* annotation.
*
* @see TargetMethodAnnotationDrivenBinder
*/
enum Binder implements TargetMethodAnnotationDrivenBinder.ParameterBinder {
/**
* The singleton instance.
*/
INSTANCE;
/**
* A method reference to the strategy property.
*/
private static final MethodDescription.InDefinedShape STRATEGY;
/**
* A reference to the proxy type property.
*/
private static final MethodDescription.InDefinedShape PROXY_TYPE;
/*
* Extracts method references of the super annotation.
*/
static {
MethodList annotationProperties = new TypeDescription.ForLoadedType(Super.class).getDeclaredMethods();
STRATEGY = annotationProperties.filter(named("strategy")).getOnly();
PROXY_TYPE = annotationProperties.filter(named("proxyType")).getOnly();
}
@Override
public Class getHandledType() {
return Super.class;
}
@Override
public MethodDelegationBinder.ParameterBinding bind(AnnotationDescription.Loadable annotation,
MethodDescription source,
ParameterDescription target,
Implementation.Target implementationTarget,
Assigner assigner) {
if (target.getType().isPrimitive() || target.getType().isArray()) {
throw new IllegalStateException(target + " uses the @Super annotation on an invalid type");
}
TypeDescription proxyType = TypeLocator.ForType
.of(annotation.getValue(PROXY_TYPE, TypeDescription.class))
.resolve(implementationTarget.getInstrumentedType(), target.getType());
if (proxyType.isFinal()) {
throw new IllegalStateException("Cannot extend final type as @Super proxy: " + proxyType);
} else if (source.isStatic() || !implementationTarget.getInstrumentedType().isAssignableTo(proxyType)) {
return MethodDelegationBinder.ParameterBinding.Illegal.INSTANCE;
} else {
return new MethodDelegationBinder.ParameterBinding.Anonymous(annotation
.getValue(STRATEGY, EnumerationDescription.class).load(Instantiation.class)
.proxyFor(proxyType, implementationTarget, annotation));
}
}
@Override
public String toString() {
return "Super.Binder." + name();
}
/**
* Locates the type which should be the base type of the created proxy.
*/
protected interface TypeLocator {
/**
* Resolves the target type.
*
* @param instrumentedType The instrumented type.
* @param parameterType The type of the target parameter.
* @return The proxy type.
*/
TypeDescription resolve(TypeDescription instrumentedType, TypeDescription.Generic parameterType);
/**
* A type locator that yields the instrumented type.
*/
enum ForInstrumentedType implements TypeLocator {
/**
* The singleton instance.
*/
INSTANCE;
@Override
public TypeDescription resolve(TypeDescription instrumentedType, TypeDescription.Generic parameterType) {
return instrumentedType;
}
@Override
public String toString() {
return "Super.Binder.TypeLocator.ForInstrumentedType." + name();
}
}
/**
* A type locator that yields the target parameter's type.
*/
enum ForParameterType implements TypeLocator {
/**
* The singleton instance.
*/
INSTANCE;
@Override
public TypeDescription resolve(TypeDescription instrumentedType, TypeDescription.Generic parameterType) {
TypeDescription erasure = parameterType.asErasure();
return erasure.equals(instrumentedType)
? instrumentedType
: erasure;
}
@Override
public String toString() {
return "Super.Binder.TypeLocator.ForParameterType." + name();
}
}
/**
* A type locator that returns a given type.
*/
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.represents(TargetType.class)) {
return ForInstrumentedType.INSTANCE;
} else if (typeDescription.isPrimitive() || typeDescription.isArray()) {
throw new IllegalStateException("Cannot assign proxy to " + typeDescription);
} else {
return new ForType(typeDescription);
}
}
@Override
public TypeDescription resolve(TypeDescription instrumentedType, TypeDescription.Generic parameterType) {
if (!typeDescription.isAssignableTo(parameterType.asErasure())) {
throw new IllegalStateException("Impossible to assign " + typeDescription + " to parameter of type " + parameterType);
}
return typeDescription;
}
@Override
public boolean equals(Object other) {
if (this == other) return true;
if (other == null || getClass() != other.getClass()) return false;
ForType forType = (ForType) other;
return typeDescription.equals(forType.typeDescription);
}
@Override
public int hashCode() {
return typeDescription.hashCode();
}
@Override
public String toString() {
return "Super.Binder.TypeLocator.ForType{" +
"typeDescription=" + typeDescription +
'}';
}
}
}
}
}