net.bytebuddy.implementation.bytecode.assign.Assigner 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.bytecode.assign;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.implementation.bytecode.StackManipulation;
import net.bytebuddy.implementation.bytecode.assign.primitive.PrimitiveTypeAwareAssigner;
import net.bytebuddy.implementation.bytecode.assign.primitive.VoidAwareAssigner;
import net.bytebuddy.implementation.bytecode.assign.reference.GenericTypeAwareAssigner;
import net.bytebuddy.implementation.bytecode.assign.reference.ReferenceTypeAwareAssigner;
/**
* An assigner is responsible for converting some type {@code A} to another type {@code B} if possible.
*
* An assigner is for example responsible for type casting, auto boxing or unboxing or for the widening of primitive
* types.
*/
@SuppressFBWarnings(value = "IC_SUPERCLASS_USES_SUBCLASS_DURING_INITIALIZATION", justification = "Safe initialization is implied.")
public interface Assigner {
/**
* A default assigner that can handle {@code void}, primitive types and reference types which considers generic types as raw types.
*/
Assigner DEFAULT = new VoidAwareAssigner(new PrimitiveTypeAwareAssigner(ReferenceTypeAwareAssigner.INSTANCE));
/**
* A generics-aware assigner that can handle {@code void}, primitive types which reference types.
*/
Assigner GENERICS_AWARE = new VoidAwareAssigner(new PrimitiveTypeAwareAssigner(GenericTypeAwareAssigner.INSTANCE));
/**
* @param source The original type that is to be transformed into the {@code targetType}.
* @param target The target type into which the {@code sourceType} is to be converted.
* @param typing A hint whether the assignment should consider the runtime type of the source type,
* i.e. if type down or cross castings are allowed. If this hint is set, this is
* also an indication that {@code void} to non-{@code void} assignments are permitted.
* @return A stack manipulation that transforms the {@code sourceType} into the {@code targetType} if this
* is possible. An illegal stack manipulation otherwise.
*/
StackManipulation assign(TypeDescription.Generic source, TypeDescription.Generic target, Typing typing);
/**
* Indicates for a type assignment, if a type casting should be applied in case that two types are not statically assignable.
* Also, a dynamic typing indicates that void values are assignable to other types by assigning the target type's default value.
*/
enum Typing {
/**
* Requires static typing.
*/
STATIC(false),
/**
* Allows dynamic typing.
*/
DYNAMIC(true);
/**
* {@code true} if dynamic typing is a legitimate choice.
*/
private final boolean dynamic;
/**
* Creates a new typing hint.
*
* @param dynamic {@code true} if dynamic typing is a legitimate choice.
*/
Typing(boolean dynamic) {
this.dynamic = dynamic;
}
/**
* Resolves a typing constant for the presented boolean where {@code true} indicates that dynamic typing is a legitimate choice.
*
* @param dynamic An indicator for if dynamic typing is a legitimate choice.
* @return A corresponding typing constant.
*/
public static Typing of(boolean dynamic) {
return dynamic
? DYNAMIC
: STATIC;
}
/**
* Checks if this instance's typing behavior permits dynamic typing.
*
* @return {@code true} if dynamic typing is a legitimate choice.
*/
public boolean isDynamic() {
return dynamic;
}
}
/**
* An assigner that only allows to assign types if they are equal to another.
*/
enum EqualTypesOnly implements Assigner {
/**
* An type assigner that only considers equal generic types to be assignable.
*/
GENERIC {
/** {@inheritDoc} */
public StackManipulation assign(TypeDescription.Generic source, TypeDescription.Generic target, Typing typing) {
return source.equals(target)
? StackManipulation.Trivial.INSTANCE
: StackManipulation.Illegal.INSTANCE;
}
},
/**
* A type assigner that considers two generic types to be equal if their erasure is equal.
*/
ERASURE {
/** {@inheritDoc} */
public StackManipulation assign(TypeDescription.Generic source, TypeDescription.Generic target, Typing typing) {
return source.asErasure().equals(target.asErasure())
? StackManipulation.Trivial.INSTANCE
: StackManipulation.Illegal.INSTANCE;
}
}
}
/**
* An assigner that does not allow any assignments.
*/
enum Refusing implements Assigner {
/**
* The singleton instance.
*/
INSTANCE;
/**
* {@inheritDoc}
*/
public StackManipulation assign(TypeDescription.Generic source, TypeDescription.Generic target, Typing typing) {
return StackManipulation.Illegal.INSTANCE;
}
}
}