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net.bytebuddy.implementation.bind.annotation.FieldGetterHandle Maven / Gradle / Ivy

/*
 * Copyright 2014 - Present Rafael Winterhalter
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.bytebuddy.implementation.bind.annotation;

import net.bytebuddy.description.annotation.AnnotationDescription;
import net.bytebuddy.description.field.FieldDescription;
import net.bytebuddy.description.method.MethodDescription;
import net.bytebuddy.description.method.MethodList;
import net.bytebuddy.description.method.ParameterDescription;
import net.bytebuddy.description.type.TypeDefinition;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.description.type.TypeList;
import net.bytebuddy.implementation.Implementation;
import net.bytebuddy.implementation.bind.MethodDelegationBinder;
import net.bytebuddy.implementation.bytecode.StackManipulation;
import net.bytebuddy.implementation.bytecode.assign.Assigner;
import net.bytebuddy.implementation.bytecode.member.MethodInvocation;
import net.bytebuddy.implementation.bytecode.member.MethodVariableAccess;
import net.bytebuddy.utility.JavaConstant;
import net.bytebuddy.utility.JavaType;
import org.objectweb.asm.Opcodes;

import java.lang.annotation.*;

import static net.bytebuddy.matcher.ElementMatchers.named;

/**
 * 

* Assigns a {@code java.lang.invoke.MethodHandle} to the annotated parameter which represents a getter of the represented field. * For a binding to be valid, the instrumented type must be able to access a field of the given name. *

*

* Setting {@link FieldGetterHandle#value()} is optional. If the value is not set, the field value attempts to bind a setter's * or getter's field if the intercepted method is an accessor method. Otherwise, the binding renders the target method * to be an illegal candidate for binding. *

*

* Important: Don't confuse this annotation with {@link net.bytebuddy.asm.Advice.FieldGetterHandle} or * {@link net.bytebuddy.asm.MemberSubstitution.FieldSetterHandle}. This annotation should be used with * {@link net.bytebuddy.implementation.MethodDelegation} only. *

* * @see net.bytebuddy.implementation.MethodDelegation * @see TargetMethodAnnotationDrivenBinder * @see RuntimeType */ @Documented @Retention(RetentionPolicy.RUNTIME) @Target(ElementType.PARAMETER) public @interface FieldGetterHandle { /** * The name of the field to be accessed. * * @return The name of the field. */ String value() default TargetMethodAnnotationDrivenBinder.ParameterBinder.ForFieldBinding.BEAN_PROPERTY; /** * Defines the type on which the field is declared. If this value is not set, the most specific type's field is read, * if two fields with the same name exist in the same type hierarchy. * * @return The type that declares the accessed field. */ Class declaringType() default void.class; /** * Binds a {@link FieldGetterHandle} annotation. */ enum Binder implements TargetMethodAnnotationDrivenBinder.ParameterBinder { /** * The singleton instance. */ INSTANCE(new Delegate()); /** * The annotation method that for the defining type. */ private static final MethodDescription.InDefinedShape DECLARING_TYPE; /** * The annotation method for the field's name. */ private static final MethodDescription.InDefinedShape FIELD_NAME; /* * Initializes the methods of the annotation that is read by this binder. */ static { MethodList methodList = TypeDescription.ForLoadedType.of(FieldGetterHandle.class).getDeclaredMethods(); DECLARING_TYPE = methodList.filter(named("declaringType")).getOnly(); FIELD_NAME = methodList.filter(named("value")).getOnly(); } /** * A delegate parameter binder responsible for binding the parameter. */ private final TargetMethodAnnotationDrivenBinder.ParameterBinder delegate; /** * Creates a new binder for a {@link FieldGetterHandle}. * * @param delegate A delegate parameter binder responsible for binding the parameter. */ Binder(TargetMethodAnnotationDrivenBinder.ParameterBinder delegate) { this.delegate = delegate; } /** * {@inheritDoc} */ public Class getHandledType() { return delegate.getHandledType(); } /** * {@inheritDoc} */ public MethodDelegationBinder.ParameterBinding bind(AnnotationDescription.Loadable annotation, MethodDescription source, ParameterDescription target, Implementation.Target implementationTarget, Assigner assigner, Assigner.Typing typing) { return delegate.bind(annotation, source, target, implementationTarget, assigner, typing); } /** * A delegate implementation for the {@link FieldGetterHandle.Binder}. */ protected static class Delegate extends ForFieldBinding { /** * {@inheritDoc} */ public Class getHandledType() { return FieldGetterHandle.class; } @Override protected String fieldName(AnnotationDescription.Loadable annotation) { return annotation.getValue(FIELD_NAME).resolve(String.class); } @Override protected TypeDescription declaringType(AnnotationDescription.Loadable annotation) { return annotation.getValue(DECLARING_TYPE).resolve(TypeDescription.class); } @Override protected MethodDelegationBinder.ParameterBinding bind(FieldDescription fieldDescription, AnnotationDescription.Loadable annotation, MethodDescription source, ParameterDescription target, Implementation.Target implementationTarget, Assigner assigner) { if (!target.getType().asErasure().isAssignableFrom(JavaType.METHOD_HANDLE.getTypeStub())) { throw new IllegalStateException("Cannot assign method handle to " + target); } else if (fieldDescription.isStatic()) { return new MethodDelegationBinder.ParameterBinding.Anonymous(JavaConstant.MethodHandle.ofGetter(fieldDescription.asDefined()).toStackManipulation()); } else { return new MethodDelegationBinder.ParameterBinding.Anonymous(new StackManipulation.Compound( JavaConstant.MethodHandle.ofGetter(fieldDescription.asDefined()).toStackManipulation(), MethodVariableAccess.loadThis(), MethodInvocation.invoke(new MethodDescription.Latent(JavaType.METHOD_HANDLE.getTypeStub(), new MethodDescription.Token("bindTo", Opcodes.ACC_PUBLIC, JavaType.METHOD_HANDLE.getTypeStub().asGenericType(), new TypeList.Generic.Explicit(TypeDefinition.Sort.describe(Object.class))))))); } } } } }




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