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SingletonEnhancer.java
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121 lines (105 loc) · 3.76 KB
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package act.util;
/*-
* #%L
* ACT Framework
* %%
* Copyright (C) 2014 - 2017 ActFramework
* %%
* 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.
* #L%
*/
import act.asm.AnnotationVisitor;
import act.asm.MethodVisitor;
import act.asm.Type;
import org.osgl.$;
import org.osgl.util.S;
import javax.inject.Singleton;
/**
* If a certain non-abstract/public class extends {@link SingletonBase} ensure the class
* has {@link javax.inject.Singleton} annotation, and generate {@link SingletonBase#instance()}
* implementation
*/
@SuppressWarnings("unused")
public class SingletonEnhancer extends AppByteCodeEnhancer<SingletonEnhancer> {
private boolean shouldEnhance = false;
private boolean shouldAddAnnotation = true;
private String typeName;
public SingletonEnhancer() {
super($.F.<String>yes());
}
@Override
protected Class<SingletonEnhancer> subClass() {
return SingletonEnhancer.class;
}
@Override
protected void reset() {
this.shouldAddAnnotation = true;
this.shouldEnhance = false;
this.typeName = null;
super.reset();
}
@Override
public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {
super.visit(version, access, name, signature, superName, interfaces);
this.typeName = name;
if (SingletonBase.class.getName().equals(Type.getObjectType(superName).getClassName())) {
if (isAbstract(access)) {
logger.warn("SingletonBase sub class is abstract: %s", name);
return;
} else if (!isPublic(access)) {
logger.warn("SingletonBase sub class is not public: %s", name);
return;
}
shouldEnhance = true;
}
}
@Override
public AnnotationVisitor visitAnnotation(String desc, boolean visible) {
Type type = Type.getType(desc);
if (Singleton.class.getName().equals(type.getClassName())) {
shouldAddAnnotation = false;
shouldEnhance = true;
}
return super.visitAnnotation(desc, visible);
}
@Override
public void visitEnd() {
if (shouldEnhance) {
addAnnotationIfNeeded();
addInstanceMethod();
}
super.visitEnd();
}
private void addAnnotationIfNeeded() {
if (shouldAddAnnotation) {
AnnotationVisitor av = super.visitAnnotation(Type.getType(Singleton.class).getDescriptor(), true);
av.visitEnd();
}
}
private void addInstanceMethod() {
MethodVisitor mv = super.visitMethod(ACC_PUBLIC + ACC_STATIC, "instance", "()Ljava/lang/Object;", "<T:Ljava/lang/Object;>()TT;", null);
mv.visitCode();
mv.visitMethodInsn(INVOKESTATIC, "act/app/App", "instance", "()Lact/app/App;", false);
mv.visitLdcInsn(Type.getType(instanceTypeDesc()));
mv.visitMethodInsn(INVOKEVIRTUAL, "act/app/App", "singleton", "(Ljava/lang/Class;)Ljava/lang/Object;", false);
mv.visitInsn(ARETURN);
mv.visitMaxs(2, 0);
mv.visitEnd();
}
private String instanceMethodReturnTypeDesc() {
return S.fmt("()L%s;", typeName);
}
private String instanceTypeDesc() {
return S.fmt("L%s;", typeName);
}
}