/*
* Copyright 2014 - 2018 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.dynamic.scaffold;
import net.bytebuddy.description.type.
TypeDescription;
import net.bytebuddy.pool.
TypePool;
import net.bytebuddy.jar.asm.
ClassReader;
import net.bytebuddy.jar.asm.
ClassWriter;
/**
* A class writer strategy is responsible for the creation of a {@link ClassWriter} when creating a type.
*/
public interface
ClassWriterStrategy {
/**
* Resolves a class writer.
*
* @param flags The flags to set.
* @param typePool A type pool for locating types.
* @return The class writer to use.
*/
ClassWriter resolve(int
flags,
TypePool typePool);
/**
* Resolves a class writer.
*
* @param flags The flags to set.
* @param typePool A type pool for locating types.
* @param classReader The class reader from which the original class is read.
* @return The class writer to use.
*/
ClassWriter resolve(int
flags,
TypePool typePool,
ClassReader classReader);
/**
* Default implementations of class writer strategies.
*/
enum
Default implements
ClassWriterStrategy {
/**
* A class writer strategy that retains the original class's constant pool if applicable.
*/
CONSTANT_POOL_RETAINING {
/** {@inheritDoc} */
public
ClassWriter resolve(int
flags,
TypePool typePool,
ClassReader classReader) {
return new
FrameComputingClassWriter(
classReader,
flags,
typePool);
}
},
/**
* A class writer strategy that discards the original class's constant pool if applicable.
*/
CONSTANT_POOL_DISCARDING {
/** {@inheritDoc} */
public
ClassWriter resolve(int
flags,
TypePool typePool,
ClassReader classReader) {
return
resolve(
flags,
typePool);
}
};
/**
* {@inheritDoc}
*/
public
ClassWriter resolve(int
flags,
TypePool typePool) {
return new
FrameComputingClassWriter(
flags,
typePool);
}
}
/**
* A class writer that piggy-backs on Byte Buddy's {@link TypePool} to avoid class loading or look-up errors when redefining a class.
* This is not available when creating a new class where automatic frame computation is however not normally a requirement.
*/
class
FrameComputingClassWriter extends
ClassWriter {
/**
* The type pool to use for computing stack map frames, if required.
*/
private final
TypePool typePool;
/**
* Creates a new frame computing class writer.
*
* @param flags The flags to be handed to the writer.
* @param typePool The type pool to use for computing stack map frames, if required.
*/
public
FrameComputingClassWriter(int
flags,
TypePool typePool) {
super(
flags);
this.
typePool =
typePool;
}
/**
* Creates a new frame computing class writer.
*
* @param classReader The class reader from which the original class is read.
* @param flags The flags to be handed to the writer.
* @param typePool The type pool to use for computing stack map frames, if required.
*/
public
FrameComputingClassWriter(
ClassReader classReader, int
flags,
TypePool typePool) {
super(
classReader,
flags);
this.
typePool =
typePool;
}
/**
* {@inheritDoc}
*/
protected
String getCommonSuperClass(
String leftTypeName,
String rightTypeName) {
TypeDescription leftType =
typePool.
describe(
leftTypeName.
replace('/', '.')).
resolve();
TypeDescription rightType =
typePool.
describe(
rightTypeName.
replace('/', '.')).
resolve();
if (
leftType.
isAssignableFrom(
rightType)) {
return
leftType.
getInternalName();
} else if (
leftType.
isAssignableTo(
rightType)) {
return
rightType.
getInternalName();
} else if (
leftType.
isInterface() ||
rightType.
isInterface()) {
return
TypeDescription.
OBJECT.
getInternalName();
} else {
do {
leftType =
leftType.
getSuperClass().
asErasure();
} while (!
leftType.
isAssignableFrom(
rightType));
return
leftType.
getInternalName();
}
}
}
}