package net.bytebuddy.implementation.bytecode.constant;
import lombok.EqualsAndHashCode;
import net.bytebuddy.description.method.MethodDescription;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.implementation.Implementation;
import net.bytebuddy.implementation.bytecode.StackManipulation;
import net.bytebuddy.implementation.bytecode.collection.ArrayFactory;
import net.bytebuddy.implementation.bytecode.member.FieldAccess;
import net.bytebuddy.implementation.bytecode.member.MethodInvocation;
import org.objectweb.asm.MethodVisitor;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
/**
* Represents the creation of a {@link java.lang.reflect.Method} value which can be created from a given
* set of constant pool values and can therefore be considered a constant in the broader meaning.
*/
@EqualsAndHashCode
public abstract class MethodConstant implements StackManipulation {
/**
* The internal name of the {@link Class} type.
*/
private static final String CLASS_TYPE_INTERNAL_NAME = "java/lang/Class";
/**
* A description of the method to be loaded onto the stack.
*/
protected final MethodDescription.InDefinedShape methodDescription;
/**
* Creates a new method constant.
*
* @param methodDescription The method description for which the {@link java.lang.reflect.Method} representation
* should be created.
*/
protected MethodConstant(MethodDescription.InDefinedShape methodDescription) {
this.methodDescription = methodDescription;
}
/**
* Creates a stack manipulation that loads a method constant onto the operand stack.
*
* @param methodDescription The method to be loaded onto the stack.
* @return A stack manipulation that assigns a method constant for the given method description.
*/
public static CanCache forMethod(MethodDescription.InDefinedShape methodDescription) {
if (methodDescription.isTypeInitializer()) {
return CanCacheIllegal.INSTANCE;
} else if (methodDescription.isConstructor()) {
return new ForConstructor(methodDescription);
} else {
return new ForMethod(methodDescription);
}
}
/**
* Returns a list of type constant load operations for the given list of parameters.
*
* @param parameterTypes A list of all type descriptions that should be represented as type constant
* load operations.
* @return A corresponding list of type constant load operations.
*/
private static List<StackManipulation> typeConstantsFor(List<TypeDescription> parameterTypes) {
List<StackManipulation> typeConstants = new ArrayList<StackManipulation>(parameterTypes.size());
for (TypeDescription parameterType : parameterTypes) {
typeConstants.add(ClassConstant.of(parameterType));
}
return typeConstants;
}
@Override
public boolean isValid() {
return true;
}
@Override
public Size apply(MethodVisitor methodVisitor, Implementation.Context implementationContext) {
return new Compound(
preparation(),
ArrayFactory.forType(new TypeDescription.Generic.OfNonGenericType.ForLoadedType(Class.class))
.withValues(typeConstantsFor(methodDescription.getParameters().asTypeList().asErasures())),
MethodInvocation.invoke(accessorMethod())
).apply(methodVisitor, implementationContext);
}
/**
* Returns a stack manipulation that loads the values that are required for loading a method constant onto the operand stack.
*
* @return A stack manipulation for loading a method or constructor onto the operand stack.
*/
protected abstract StackManipulation preparation();
/**
* Returns the method for loading a declared method or constructor onto the operand stack.
*
* @return The method for loading a declared method or constructor onto the operand stack.
*/
protected abstract MethodDescription accessorMethod();
/**
* Returns a cached version of this method constant as specified by {@link CachedMethod} and {@link CachedConstructor}.
*
* @return A cached version of this method constant.
*/
public StackManipulation cached() {
return methodDescription.isConstructor()
? new CachedConstructor(this)
: new CachedMethod(this);
}
/**
* Represents a method constant that cannot be represented by Java's reflection API.
*/
protected enum CanCacheIllegal implements CanCache {
/**
* The singleton instance.
*/
INSTANCE;
@Override
public StackManipulation cached() {
return Illegal.INSTANCE;
}
@Override
public boolean isValid() {
return false;
}
@Override
public Size apply(MethodVisitor methodVisitor, Implementation.Context implementationContext) {
return Illegal.INSTANCE.apply(methodVisitor, implementationContext);
}
}
/**
* Represents a {@link net.bytebuddy.implementation.bytecode.constant.MethodConstant} that is
* directly loaded onto the operand stack without caching the value. Since the look-up of a Java method bares
* some costs that sometimes need to be avoided, such a stack manipulation offers a convenience method for
* defining this loading instruction as the retrieval of a field value that is initialized in the instrumented
* type's type initializer.
*/
public interface CanCache extends StackManipulation {
/**
* Returns this method constant as a cached version.
*
* @return A cached version of the method constant that is represented by this instance.
*/
StackManipulation cached();
}
/**
* Creates a {@link net.bytebuddy.implementation.bytecode.constant.MethodConstant} for loading
* a {@link java.lang.reflect.Method} instance onto the operand stack.
*/
protected static class ForMethod extends MethodConstant implements CanCache {
/**
* Creates a new {@link net.bytebuddy.implementation.bytecode.constant.MethodConstant} for
* creating a {@link java.lang.reflect.Method} instance.
*
* @param methodDescription The method to be loaded onto the stack.
*/
protected ForMethod(MethodDescription.InDefinedShape methodDescription) {
super(methodDescription);
}
@Override
protected StackManipulation preparation() {
return new Compound(ClassConstant.of(methodDescription.getDeclaringType()), new TextConstant(methodDescription.getInternalName()));
}
@Override
protected MethodDescription accessorMethod() {
try {
return new MethodDescription.ForLoadedMethod(Class.class.getMethod("getDeclaredMethod", String.class, Class[].class));
} catch (NoSuchMethodException exception) {
throw new IllegalStateException("Cannot locate Class::getDeclaredMethod", exception);
}
}
}
/**
* Creates a {@link net.bytebuddy.implementation.bytecode.constant.MethodConstant} for loading
* a {@link java.lang.reflect.Constructor} instance onto the operand stack.
*/
protected static class ForConstructor extends MethodConstant implements CanCache {
/**
* Creates a new {@link net.bytebuddy.implementation.bytecode.constant.MethodConstant} for
* creating a {@link java.lang.reflect.Constructor} instance.
*
* @param methodDescription The constructor to be loaded onto the stack.
*/
protected ForConstructor(MethodDescription.InDefinedShape methodDescription) {
super(methodDescription);
}
@Override
protected StackManipulation preparation() {
return ClassConstant.of(methodDescription.getDeclaringType());
}
@Override
protected MethodDescription accessorMethod() {
try {
return new MethodDescription.ForLoadedMethod(Class.class.getMethod("getDeclaredConstructor", Class[].class));
} catch (NoSuchMethodException exception) {
throw new IllegalStateException("Cannot locate Class::getDeclaredConstructor", exception);
}
}
}
/**
* Represents a cached method for a {@link net.bytebuddy.implementation.bytecode.constant.MethodConstant}.
*/
@EqualsAndHashCode
protected static class CachedMethod implements StackManipulation {
/**
* A description of the {@link java.lang.reflect.Method} type.
*/
private static final TypeDescription METHOD_TYPE = new TypeDescription.ForLoadedType(Method.class);
/**
* The stack manipulation that is represented by this caching wrapper.
*/
private final StackManipulation methodConstant;
/**
* Creates a new cached {@link net.bytebuddy.implementation.bytecode.constant.MethodConstant}.
*
* @param methodConstant The method constant to store in the field cache.
*/
protected CachedMethod(StackManipulation methodConstant) {
this.methodConstant = methodConstant;
}
@Override
public boolean isValid() {
return methodConstant.isValid();
}
@Override
public Size apply(MethodVisitor methodVisitor, Implementation.Context implementationContext) {
return FieldAccess.forField(implementationContext.cache(methodConstant, METHOD_TYPE))
.read()
.apply(methodVisitor, implementationContext);
}
}
/**
* Represents a cached constructor for a {@link net.bytebuddy.implementation.bytecode.constant.MethodConstant}.
*/
@EqualsAndHashCode
protected static class CachedConstructor implements StackManipulation {
/**
* A description of the {@link java.lang.reflect.Constructor} type.
*/
private static final TypeDescription CONSTRUCTOR_TYPE = new TypeDescription.ForLoadedType(Constructor.class);
/**
* The stack manipulation that is represented by this caching wrapper.
*/
private final StackManipulation constructorConstant;
/**
* Creates a new cached {@link net.bytebuddy.implementation.bytecode.constant.MethodConstant}.
*
* @param constructorConstant The method constant to store in the field cache.
*/
protected CachedConstructor(StackManipulation constructorConstant) {
this.constructorConstant = constructorConstant;
}
@Override
public boolean isValid() {
return constructorConstant.isValid();
}
@Override
public Size apply(MethodVisitor methodVisitor, Implementation.Context implementationContext) {
return FieldAccess.forField(implementationContext.cache(constructorConstant, CONSTRUCTOR_TYPE))
.read()
.apply(methodVisitor, implementationContext);
}
}
}