AfterObjectInitializationCodeAdapter.java

/**************************************************************************************
 * Copyright (c) Jonas Bon�r, Alexandre Vasseur. All rights reserved.                 *
 * http://aspectwerkz.codehaus.org                                                    *
 * ---------------------------------------------------------------------------------- *
 * The software in this package is published under the terms of the LGPL license      *
 * a copy of which has been included with this distribution in the license.txt file.  *
 **************************************************************************************/
package org.codehaus.aspectwerkz.transform.inlining.weaver;

import org.objectweb.asm.MethodAdapter;
import org.objectweb.asm.MethodVisitor;
import org.codehaus.aspectwerkz.transform.TransformationConstants;
import org.codehaus.aspectwerkz.transform.inlining.AsmNullAdapter;

/**
 * A visitor that keeps track of NEW and INVOKESPECIAL when within a constructor
 * to flag when the object initialization has been reached (after this/super call).
 * <p/>
 * No regular weaving should occur before it since this(XXJP.invoke(this)) is not allowed Java code
 *
 * @author <a href="mailto:alex AT gnilux DOT com">Alexandre Vasseur</a>
 */
public class AfterObjectInitializationCodeAdapter extends MethodAdapter implements TransformationConstants {

    private String m_callerMemberName;
    private int m_newCount = 0;
    private int m_invokeSpecialCount = 0;
    protected boolean m_isObjectInitialized = false;

    public AfterObjectInitializationCodeAdapter(MethodVisitor cv, String callerMemberName) {
        super(cv);
        m_callerMemberName = callerMemberName;
        // object initialization matters within constructors only
        if (!m_callerMemberName.equals(INIT_METHOD_NAME)) {
            m_isObjectInitialized = true;
        }
    }

    public void visitTypeInsn(int opcode, String desc) {
        if (opcode == NEW) {
            m_newCount++;
        }
        super.visitTypeInsn(opcode, desc);
    }

    protected boolean queryCurrentMethodInsn(final int opcode,
                                final String calleeClassName,
                                final String calleeMethodName,
                                final String calleeMethodDesc) {
        int localInvokeSpecialCount = m_invokeSpecialCount;
        int localNewCount = m_newCount;

        if (opcode == INVOKESPECIAL) {
            localInvokeSpecialCount++;
        }

        if (m_callerMemberName.equals(INIT_METHOD_NAME)) {
            // in ctor
            // make sure we are after object initialization ie after
            // the INVOKESPECIAL for this(..) / super(..)
            // that is we have seen an INVOKESPECIAL while newCount == 0
            // or while newCount == invokeSpecialCount - 1
            // [ ie same with numberOfInvokeSpecialCount = 1 ]
            if (opcode == INVOKESPECIAL) {
                if (localNewCount == localInvokeSpecialCount -1) {
                    return true;
                }
            }
            return false;
        }
        return false;
    }

    public void visitMethodInsn(final int opcode,
                                final String calleeClassName,
                                final String calleeMethodName,
                                final String calleeMethodDesc) {
        if (opcode == INVOKESPECIAL) {
            m_invokeSpecialCount++;
        }

        if (m_callerMemberName.equals(INIT_METHOD_NAME)) {
            // in ctor
            // make sure we are after object initialization ie after
            // the INVOKESPECIAL for this(..) / super(..)
            // that is we have seen an INVOKESPECIAL while newCount == 0
            // or while newCount == invokeSpecialCount - 1
            // [ ie same with numberOfInvokeSpecialCount = 1 ]
            if (opcode == INVOKESPECIAL) {
                if (m_newCount == m_invokeSpecialCount -1) {
                    m_isObjectInitialized = true;
                }
            }
        }
        super.visitMethodInsn(opcode, calleeClassName, calleeMethodName, calleeMethodDesc);
    }
}