com.google.devtools.build.wireless.testing.java.injector.ReferenceTracerMethodAdapter.java Source code

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Here is the source code for com.google.devtools.build.wireless.testing.java.injector.ReferenceTracerMethodAdapter.java

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/* Copyright 2008 Google Inc.
 * 
 * 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 com.google.devtools.build.wireless.testing.java.injector;

import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;

/**
 * Allow tracing of given classes by instrumenting them to behave as singletons.
 * 
 * <p>This method adapter instruments the constructor of a given class by 
 * invoking at the end of it a static setter which store a reference to the 
 * instance. 
 * 
 * <p>The setter is supposed to be a static method of a different class 
 * invokable as setterClassName.setterMethodsName(LsingletonClassName;)
 * 
 * @author Michele Sama
 *
 */
public class ReferenceTracerMethodAdapter extends InjectorMethodAdapter {

    private String setterClassName;

    private String setterMethodsName;

    /**
     * Constructor from superclass.
     * 
     * @param mv The nested {@link MethodVisitor}.
     * @param setterClassName the name of the class containing the setter.
     * @param setterMethodName the name of the setter method.
     * @param access The method's access opcode.
     * @param visitedClass The name of the class containing this method.
     * @param methodName The method's name.
     * @param desc The method's description.
     * @param platform The target {@link Platform}.
     */
    public ReferenceTracerMethodAdapter(MethodVisitor mv, String setterClassName, String setterMethodName,
            int access, String visitedClass, String methodName, String desc, Platform platform) {
        super(mv, access, visitedClass, methodName, desc, platform);
        if (!"<init>".equals(methodName)) {
            throw new IllegalStateException("Visited method is not a constructor.");
        }
        this.setterClassName = setterClassName;
        this.setterMethodsName = setterMethodName;
    }

    /**
     * Injects, at the end of the method, which will be a constructor, a set of 
     * instruction to register this instance in the wrapper.
     * 
     * @param opcode The instruction code.
     * @see org.objectweb.asm.MethodAdapter#visitInsn(int)
     */
    @Override
    public void visitInsn(int opcode) {
        if (isReturnInstruction(opcode) || opcode == Opcodes.ATHROW) {
            stackServant.loadThis();
            mv.visitMethodInsn(Opcodes.INVOKESTATIC, setterClassName, setterMethodsName, "(L" + ownerClass + ";)V");
        }
        mv.visitInsn(opcode);
    }

}