CflowBinding.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.cflow;

import org.codehaus.aspectwerkz.expression.ExpressionInfo;
import org.codehaus.aspectwerkz.definition.SystemDefinition;
import org.codehaus.aspectwerkz.definition.AspectDefinition;
import org.codehaus.aspectwerkz.definition.AdviceDefinition;
import org.codehaus.aspectwerkz.reflect.impl.java.JavaClassInfo;
import org.codehaus.aspectwerkz.reflect.ClassInfo;
import org.codehaus.aspectwerkz.reflect.MethodInfo;
import org.codehaus.aspectwerkz.aspect.AdviceType;

import java.util.List;
import java.util.ArrayList;

/**
 * A Cflow binding represents an extracted cflow or cflowbelow subexpression
 * <p/>
 * For a given pointcut "pcA and cflowA or cflowbelowB", we will extract two bindings.
 * The m_cflowID must be unique on a per cflow sub expresion basis ie JVM wide.
 * <p/>
 * Note: CflowBinding hashcode depends on Cflow_ID (sub expr) + isCflowBelow only.
 *
 * @author <a href="mailto:alex AT gnilux DOT com">Alexandre Vasseur</a>
 */
public class CflowBinding {

    /**
     * the base implementation that hosts the cflow advices
     */
    private final static ClassInfo ABSTRACT_CFLOWCLASS = JavaClassInfo.getClassInfo(AbstractCflowSystemAspect.class);
    private final static MethodInfo CFLOW_ENTER_ADVICE;
    private final static MethodInfo CFLOW_EXIT_ADVICE;
    static {
        MethodInfo enter = null;
        MethodInfo exit = null;
        for (int i = 0; i < ABSTRACT_CFLOWCLASS.getMethods().length; i++) {
            MethodInfo methodInfo = ABSTRACT_CFLOWCLASS.getMethods()[i];
            if (methodInfo.getName().equals("enter")) {
                enter = methodInfo;
            } else if (methodInfo.getName().equals("exit")) {
                exit = methodInfo;
            }
        }
        if (enter == null || exit == null) {
            throw new Error("Could not gather cflow advices from " + AbstractCflowSystemAspect.class);
        } else {
            CFLOW_ENTER_ADVICE = enter;
            CFLOW_EXIT_ADVICE = exit;
        }
    }

    /**
     * cflow unique id
     */
    private int m_cflowID;

    /**
     * pointcut that represents this cflow sub-expression
     */
    private ExpressionInfo m_cflowSubExpression;

    /**
     * pointcut that represents the containing expression
     */
    private ExpressionInfo m_outerExpression;

    /**
     * marker if this binding is a cflow below, not used at the moment
     */
    private boolean m_isCflowBelow;

    /**
     * Cosntructs a new cflow binding
     *
     * @param cflowID
     * @param cflowSubExpression
     * @param isCflowBelow
     */
    public CflowBinding(int cflowID, ExpressionInfo cflowSubExpression, ExpressionInfo outerExpression, boolean isCflowBelow) {
        m_cflowID = cflowID;
        m_cflowSubExpression = cflowSubExpression;
        m_outerExpression = outerExpression;
        m_isCflowBelow = isCflowBelow;
    }

    /**
     * @return the sub expression
     */
    public ExpressionInfo getExpression() {
        return m_cflowSubExpression;
    }

    /**
     * Extract the cflow bindings from any pointcut
     * This includes both cflow and cflowbelow
     *
     * @param expressionInfo the pointcut expression frow where to extract the cflow bindings
     * @return a list of CflowBinding, can be empty
     */
    public static List getCflowBindingsForCflowOf(ExpressionInfo expressionInfo) {
        List cflowBindings = new ArrayList();
        if (expressionInfo != null) {
            expressionInfo.getCflowAspectExpression().populateCflowAspectBindings(cflowBindings);
        }
        return cflowBindings;
    }

    /**
     * Create an aspect definition for this cflow binding in the given system.
     * The cflow jit aspects will gets compiled and loaded
     *
     * @param systemDefinition
     * @param loader
     * @return the cflow aspect definition
     */
    public AspectDefinition getAspectDefinition(SystemDefinition systemDefinition, ClassLoader loader) {
        String aspectName = CflowCompiler.getCflowAspectClassName(m_cflowID);

        // check if we have already register this aspect
        // TODO: it may happen that the aspect gets register somewhere up in the hierarchy ??
        // it is optim only

        // TODO: how to do this class define lazyly and not pass in a classloader ?
        // could be done in the JIT jp clinit when 1+ advice has a cflow binding
        Class aspectClass = CflowCompiler.compileCflowAspectAndAttachToClassLoader(loader, m_cflowID);
        ClassInfo cflowAspectInfo = JavaClassInfo.getClassInfo(aspectClass);

        AspectDefinition aspectDef = new AspectDefinition(
                aspectName.replace('/', '.'),
                cflowAspectInfo,
                systemDefinition
        );
        aspectDef.addBeforeAdviceDefinition(
                new AdviceDefinition(
                        CFLOW_ENTER_ADVICE.getName(),
                        AdviceType.BEFORE,
                        null,
                        aspectName,
                        aspectName,
                        m_cflowSubExpression,
                        CFLOW_ENTER_ADVICE,
                        aspectDef
                )
        );
        aspectDef.addAfterAdviceDefinition(
                new AdviceDefinition(
                        CFLOW_EXIT_ADVICE.getName(),
                        AdviceType.AFTER_FINALLY,
                        null,
                        aspectName,
                        aspectName,
                        m_cflowSubExpression,
                        CFLOW_EXIT_ADVICE,
                        aspectDef
                )
        );

        return aspectDef;
    }

    public boolean isCflowBelow() {
        return m_isCflowBelow;
    }

    public int getCflowID() {
        return m_cflowID;
    }

    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof CflowBinding)) return false;

        final CflowBinding cflowBinding = (CflowBinding) o;

        if (m_cflowID != cflowBinding.m_cflowID) return false;
        if (m_isCflowBelow != cflowBinding.m_isCflowBelow) return false;

        return true;
    }

    public int hashCode() {
        int result;
        result = m_cflowID;
        result = 29 * result + (m_isCflowBelow ? 1 : 0);
        return result;
    }
}