package net.bytebuddy.implementation;
import lombok.EqualsAndHashCode;
import net.bytebuddy.description.method.MethodDescription;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.description.type.TypeList;
import net.bytebuddy.dynamic.scaffold.InstrumentedType;
import net.bytebuddy.implementation.bytecode.ByteCodeAppender;
import net.bytebuddy.implementation.bytecode.StackManipulation;
import net.bytebuddy.implementation.bytecode.member.MethodReturn;
import net.bytebuddy.implementation.bytecode.member.MethodVariableAccess;
import org.objectweb.asm.MethodVisitor;
import java.util.*;
/**
* This {@link Implementation} invokes a default method for the methods it instruments.
* A default method is potentially ambiguous if a method of identical signature is defined in several interfaces.
* For this reason, this implementation allows for the specification of <i>prioritized interfaces</i> whose default
* methods, if a method of equivalent signature is defined for a specific interface. All prioritized interfaces are
* searched for default methods in the order of their specification. If no prioritized interface defines a default method
* of equivalent signature to the given instrumented method, any non-prioritized interface is searched for a suitable
* default method. If exactly one of those interfaces defines a suitable default method, this method is invoked.
* If no method or more than one method is identified as a suitable default method, an exception is thrown.
* <p> </p>
* When it comes to default methods, the Java programming language specifies stronger requirements for the
* legitimacy of invoking a default method than the Java runtime. The Java compiler requires a method to be
* the most specific method in its defining type's type hierarchy, i.e. the method must not be overridden by another
* interface or class type. Additionally, the method must be invokable from an interface type which is directly
* implemented by the instrumented type. The Java runtime only requires the second condition to be fulfilled which
* is why this implementation only checks the later condition, as well.
*/
@EqualsAndHashCode
public class DefaultMethodCall implements Implementation {
/**
* A list of prioritized interfaces in the order in which a method should be attempted to be called.
*/
private final List<TypeDescription> prioritizedInterfaces;
/**
* Creates a new {@link net.bytebuddy.implementation.DefaultMethodCall} implementation for a given list of
* prioritized interfaces.
*
* @param prioritizedInterfaces A list of prioritized interfaces in the order in which a method should be attempted to
* be called.
*/
protected DefaultMethodCall(List<TypeDescription> prioritizedInterfaces) {
this.prioritizedInterfaces = prioritizedInterfaces;
}
/**
* Creates a {@link net.bytebuddy.implementation.DefaultMethodCall} implementation which searches the given list
* of interface types for a suitable default method in their order. If no such prioritized interface is suitable,
* because it is either not defined on the instrumented type or because it does not define a suitable default method,
* any remaining interface is searched for a suitable default method. If no or more than one method defines a
* suitable default method, an exception is thrown.
*
* @param prioritizedInterface A list of prioritized default method interfaces in their prioritization order.
* @return An implementation which calls an instrumented method's compatible default method that considers the given
* interfaces to be prioritized in their order.
*/
public static Implementation prioritize(Class<?>... prioritizedInterface) {
return prioritize(new TypeList.ForLoadedTypes(prioritizedInterface));
}
/**
* Creates a {@link net.bytebuddy.implementation.DefaultMethodCall} implementation which searches the given list
* of interface types for a suitable default method in their order. If no such prioritized interface is suitable,
* because it is either not defined on the instrumented type or because it does not define a suitable default method,
* any remaining interface is searched for a suitable default method. If no or more than one method defines a
* suitable default method, an exception is thrown.
*
* @param prioritizedInterfaces A list of prioritized default method interfaces in their prioritization order.
* @return An implementation which calls an instrumented method's compatible default method that considers the given
* interfaces to be prioritized in their order.
*/
public static Implementation prioritize(Iterable<? extends Class<?>> prioritizedInterfaces) {
List<Class<?>> list = new ArrayList<Class<?>>();
for (Class<?> prioritizedInterface : prioritizedInterfaces) {
list.add(prioritizedInterface);
}
return prioritize(new TypeList.ForLoadedTypes(list));
}
/**
* Creates a {@link net.bytebuddy.implementation.DefaultMethodCall} implementation which searches the given list
* of interface types for a suitable default method in their order. If no such prioritized interface is suitable,
* because it is either not defined on the instrumented type or because it does not define a suitable default method,
* any remaining interface is searched for a suitable default method. If no or more than one method defines a
* suitable default method, an exception is thrown.
*
* @param prioritizedInterface A list of prioritized default method interfaces in their prioritization order.
* @return An implementation which calls an instrumented method's compatible default method that considers the given
* interfaces to be prioritized in their order.
*/
public static Implementation prioritize(TypeDescription... prioritizedInterface) {
return prioritize(Arrays.asList(prioritizedInterface));
}
/**
* Creates a {@link net.bytebuddy.implementation.DefaultMethodCall} implementation which searches the given list
* of interface types for a suitable default method in their order. If no such prioritized interface is suitable,
* because it is either not defined on the instrumented type or because it does not define a suitable default method,
* any remaining interface is searched for a suitable default method. If no or more than one method defines a
* suitable default method, an exception is thrown.
*
* @param prioritizedInterfaces A collection of prioritized default method interfaces in their prioritization order.
* @return An implementation which calls an instrumented method's compatible default method that considers the given
* interfaces to be prioritized in their order.
*/
public static Implementation prioritize(Collection<? extends TypeDescription> prioritizedInterfaces) {
return new DefaultMethodCall(new ArrayList<TypeDescription>(prioritizedInterfaces));
}
/**
* Creates a {@link net.bytebuddy.implementation.DefaultMethodCall} implementation without prioritizing any
* interface. Instead, any interface that is defined for a given type is searched for a suitable default method. If
* exactly one interface defines a suitable default method, this method is invoked from the instrumented method.
* Otherwise, an exception is thrown.
*
* @return An implementation which calls an instrumented method's compatible default method if such a method
* is unambiguous.
*/
public static Implementation unambiguousOnly() {
return new DefaultMethodCall(Collections.<TypeDescription>emptyList());
}
@Override
public InstrumentedType prepare(InstrumentedType instrumentedType) {
return instrumentedType;
}
@Override
public ByteCodeAppender appender(Target implementationTarget) {
return new Appender(implementationTarget, filterRelevant(implementationTarget.getInstrumentedType()));
}
/**
* Filters the relevant prioritized interfaces for a given type, i.e. finds the types that are
* directly declared on a given instrumented type.
*
* @param typeDescription The instrumented type for which the prioritized interfaces are to be filtered.
* @return A list of prioritized interfaces that are additionally implemented by the given type.
*/
private List<TypeDescription> filterRelevant(TypeDescription typeDescription) {
List<TypeDescription> filtered = new ArrayList<TypeDescription>(prioritizedInterfaces.size());
Set<TypeDescription> relevant = new HashSet<TypeDescription>(typeDescription.getInterfaces().asErasures());
for (TypeDescription prioritizedInterface : prioritizedInterfaces) {
if (relevant.remove(prioritizedInterface)) {
filtered.add(prioritizedInterface);
}
}
return filtered;
}
/**
* The appender for implementing a {@link net.bytebuddy.implementation.DefaultMethodCall}.
*/
@EqualsAndHashCode(exclude = "nonPrioritizedInterfaces")
protected static class Appender implements ByteCodeAppender {
/**
* The implementation target of this appender.
*/
private final Target implementationTarget;
/**
* The relevant prioritized interfaces to be considered by this appender.
*/
private final List<TypeDescription> prioritizedInterfaces;
/**
* The relevant non-prioritized interfaces to be considered by this appender.
*/
private final Set<TypeDescription> nonPrioritizedInterfaces;
/**
* Creates a new appender for implementing a {@link net.bytebuddy.implementation.DefaultMethodCall}.
*
* @param implementationTarget The implementation target of this appender.
* @param prioritizedInterfaces The relevant prioritized interfaces to be considered by this appender.
*/
protected Appender(Target implementationTarget, List<TypeDescription> prioritizedInterfaces) {
this.implementationTarget = implementationTarget;
this.prioritizedInterfaces = prioritizedInterfaces;
this.nonPrioritizedInterfaces = new HashSet<TypeDescription>(implementationTarget.getInstrumentedType().getInterfaces().asErasures());
nonPrioritizedInterfaces.removeAll(prioritizedInterfaces);
}
@Override
public Size apply(MethodVisitor methodVisitor, Context implementationContext, MethodDescription instrumentedMethod) {
StackManipulation defaultMethodInvocation = locateDefault(instrumentedMethod);
if (!defaultMethodInvocation.isValid()) {
throw new IllegalStateException("Cannot invoke default method on " + instrumentedMethod);
}
StackManipulation.Size stackSize = new StackManipulation.Compound(
MethodVariableAccess.allArgumentsOf(instrumentedMethod).prependThisReference(),
defaultMethodInvocation,
MethodReturn.of(instrumentedMethod.getReturnType())
).apply(methodVisitor, implementationContext);
return new Size(stackSize.getMaximalSize(), instrumentedMethod.getStackSize());
}
/**
* Locates a special method invocation to be invoked from a given method.
*
* @param methodDescription The method that is currently instrumented.
* @return A potentially illegal stack manipulation representing the default method invocation for the
* given method.
*/
private StackManipulation locateDefault(MethodDescription methodDescription) {
MethodDescription.SignatureToken methodToken = methodDescription.asSignatureToken();
SpecialMethodInvocation specialMethodInvocation = SpecialMethodInvocation.Illegal.INSTANCE;
for (TypeDescription typeDescription : prioritizedInterfaces) {
specialMethodInvocation = implementationTarget.invokeDefault(methodToken, typeDescription);
if (specialMethodInvocation.isValid()) {
return specialMethodInvocation;
}
}
for (TypeDescription typeDescription : nonPrioritizedInterfaces) {
SpecialMethodInvocation other = implementationTarget.invokeDefault(methodToken, typeDescription);
if (specialMethodInvocation.isValid() && other.isValid()) {
throw new IllegalStateException(methodDescription + " has an ambiguous default method with "
+ other.getMethodDescription() + " and " + specialMethodInvocation.getMethodDescription());
}
specialMethodInvocation = other;
}
return specialMethodInvocation;
}
}
}