package net.bytebuddy.implementation.bind.annotation;
import net.bytebuddy.description.annotation.AnnotationDescription;
import net.bytebuddy.description.method.MethodDescription;
import net.bytebuddy.description.method.ParameterDescription;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.implementation.Implementation;
import net.bytebuddy.implementation.bind.MethodDelegationBinder;
import net.bytebuddy.implementation.bytecode.assign.Assigner;
import net.bytebuddy.implementation.bytecode.constant.*;
import net.bytebuddy.utility.JavaConstant;
import net.bytebuddy.utility.JavaType;
import java.lang.annotation.*;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
/**
* <p>
* The origin annotation provides some meta information about the source method that is bound to this method where
* the binding is dependant of the parameter's type:
* </p>
* <ol>
* <li>If the annotated parameter is of type {@link java.lang.reflect.Method}, {@link java.lang.reflect.Constructor} or
* {@code java.lang.reflect.Executable}, the parameter is assigned a reference to the method or constructor it
* instruments. If the reference is not assignable to the sort of the intercepted source, the target is not considered
* for binding.</li>
* <li>If the annotated parameter is of type {@link java.lang.Class}, the parameter is assigned a reference of the
* type of the instrumented type.</li>
* <li>If the annotated parameter is of type {@link java.lang.String}, the parameter is assigned a string with
* the value that would be returned by the {@link Method#toString()} method.
* </li>
* <li>If the annotated parameter is a {@code int} type, it is assigned the intercepted method's modifiers.</li>
* <li>If the annotated type is {@code java.lang.invoke.MethodHandle}, a handle of the intercepted method is injected.
* A {@code java.lang.invoke.MethodHandle} is stored in a class's constant pool and does therefore not face the same
* runtime performance limitations as a (non-cached) {@link java.lang.reflect.Method} reference. Method handles are
* only supported for byte code versions starting from Java 7.</li>
* <li>If the annotated type is {@code java.lang.invoke.MethodType}, a description of the intercepted method's type
* is injected. Method type descriptions are only supported for byte code versions starting from Java 7.</li>
* </ol>
* <p>
* Any other parameter type will cause an {@link java.lang.IllegalStateException}.
* </p>
* <p>
* <b>Important:</b> A method handle or method type reference can only be used if the referenced method's types are all visible
* to the instrumented type or an {@link IllegalAccessError} will be thrown at runtime.
* </p>
*
* @see net.bytebuddy.implementation.MethodDelegation
* @see net.bytebuddy.implementation.bind.annotation.TargetMethodAnnotationDrivenBinder
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
public @interface Origin {
/**
* Determines if the value that is assigned by this annotation is cached. For values that can be stored in the constant pool,
* this value is ignored as such values are cached implicitly. As a result, this value currently only affects caching of
* {@link Method} instances.
*
* @return {@code true} if the value for this parameter should be cached in a {@code static} field inside the instrumented class.
*/
boolean cache() default true;
/**
* A binder for binding parameters that are annotated with
* {@link net.bytebuddy.implementation.bind.annotation.Origin}.
*
* @see TargetMethodAnnotationDrivenBinder
*/
enum Binder implements TargetMethodAnnotationDrivenBinder.ParameterBinder<Origin> {
/**
* The singleton instance.
*/
INSTANCE;
@Override
public Class<Origin> getHandledType() {
return Origin.class;
}
@Override
public MethodDelegationBinder.ParameterBinding<?> bind(AnnotationDescription.Loadable<Origin> annotation,
MethodDescription source,
ParameterDescription target,
Implementation.Target implementationTarget,
Assigner assigner,
Assigner.Typing typing) {
TypeDescription parameterType = target.getType().asErasure();
if (parameterType.represents(Class.class)) {
return new MethodDelegationBinder.ParameterBinding.Anonymous(ClassConstant.of(implementationTarget.getOriginType().asErasure()));
} else if (parameterType.represents(Method.class)) {
return source.isMethod()
? new MethodDelegationBinder.ParameterBinding.Anonymous(
annotation.loadSilent().cache()
? MethodConstant.forMethod(source.asDefined()).cached()
: MethodConstant.forMethod(source.asDefined()))
: MethodDelegationBinder.ParameterBinding.Illegal.INSTANCE;
} else if (parameterType.represents(Constructor.class)) {
return source.isConstructor()
? new MethodDelegationBinder.ParameterBinding.Anonymous(
annotation.loadSilent().cache()
? MethodConstant.forMethod(source.asDefined()).cached()
: MethodConstant.forMethod(source.asDefined()))
: MethodDelegationBinder.ParameterBinding.Illegal.INSTANCE;
} else if (JavaType.EXECUTABLE.getTypeStub().equals(parameterType)) {
return new MethodDelegationBinder.ParameterBinding.Anonymous(annotation.loadSilent().cache()
? MethodConstant.forMethod(source.asDefined()).cached()
: MethodConstant.forMethod(source.asDefined()));
} else if (parameterType.represents(String.class)) {
return new MethodDelegationBinder.ParameterBinding.Anonymous(new TextConstant(source.toString()));
} else if (parameterType.represents(int.class)) {
return new MethodDelegationBinder.ParameterBinding.Anonymous(IntegerConstant.forValue(source.getModifiers()));
} else if (parameterType.equals(JavaType.METHOD_HANDLE.getTypeStub())) {
return new MethodDelegationBinder.ParameterBinding.Anonymous(JavaConstant.MethodHandle.of(source.asDefined()).asStackManipulation());
} else if (parameterType.equals(JavaType.METHOD_TYPE.getTypeStub())) {
return new MethodDelegationBinder.ParameterBinding.Anonymous(JavaConstant.MethodType.of(source.asDefined()).asStackManipulation());
} else {
throw new IllegalStateException("The " + target + " method's " + target.getIndex() +
" parameter is annotated with a Origin annotation with an argument not representing a Class," +
" Method, Constructor, String, int, MethodType or MethodHandle type");
}
}
}
}