connectionvisitor.java

该工具也是用于字节码插桩

/*
 * ConnectionVisitor.java
 *
 * Created on July 24, 2001, 8:21 AM
 *
 * See LICENSE file for license conditions.
 */

package residue.graph;

import org.apache.bcel.generic.*;
import java.util.*;

/**
 *
 * @author  chowells
 * @version 
 */
public class ConnectionVisitor extends EmptyVisitor
{
	private boolean shouldConnect;
	
	// InstructionHandle -> Node table
	private Map tab;
	private InstructionHandle handle;
	private int sysExitIndex;
	private int runExitIndex;
	
	private Set heads = new HashSet();
	
	public ConnectionVisitor(Map table, ConstantPoolGen cp)
	{
		tab = table;
		sysExitIndex = cp.lookupMethodref("java.lang.System", "exit", "(I)V");
		runExitIndex = cp.lookupMethodref("java.lang.Runtime", "exit", "(I)V");
	} // ConnectionVisitor
	
	public boolean shouldConnectToNext()
	{
		return shouldConnect;
	} // connectToNext
	
	public void startVisit(InstructionHandle ih)
	{
		if (ih.getPrev() == null) heads.add(ih);
		shouldConnect = true;
		handle = ih;
		handle.accept(this);
	} // startVisit
	
	public Set getHeads()
	{
		return Collections.unmodifiableSet(heads);
	} // getHeads
	
	public void visitJsrInstruction(JsrInstruction ji)
	{
		// put its target in the set of InstructionHandles
		// that begin disconnected components of the flow graph
		heads.add(ji.getTarget());
	} // visitJsrInstruction
	
	public void visitIfInstruction(IfInstruction ii)
	{
		Node n = (Node)tab.get(handle);
		Node t = (Node)tab.get(ii.getTarget());
		n.addEdge(t);
	} // visitIfInstruction
	
	public void visitGotoInstruction(GotoInstruction gi)
	{
		Node n = (Node)tab.get(handle);
		Node t = (Node)tab.get(gi.getTarget());
		n.addEdge(t);
		shouldConnect = false;
	} // visitGotoInstruction
	
	public void visitSelect(Select s)
	{
		Node n = (Node)tab.get(handle);
		InstructionHandle [] targets = s.getTargets();
		for (int i = 0; i < targets.length; i++)
		{
			Node t = (Node)tab.get(targets[i]);
			n.addEdge(t);
		} // for
		Node t = (Node)tab.get(s.getTarget());
		n.addEdge(t);
		shouldConnect = false;
	} // visitSelect
	
	public void visitReturnInstruction(ReturnInstruction ri)
	{
		shouldConnect = false;
	} // visitReturnInstruction
	
	public void visitINVOKESTATIC(INVOKESTATIC i)
	{
		if (i.getIndex() == sysExitIndex)
			shouldConnect = false;
	} // visitINVOKESTATIC
	
	public void visitINVOKEVIRTUAL(INVOKEVIRTUAL i)
	{
		if (i.getIndex() == runExitIndex)
			shouldConnect = false;
	} // visitINVOKEVIRTUAL
	
	public void visitRET(RET r)
	{
		shouldConnect = false;
	} // visitRet
	
	public void visitATHROW(ATHROW th)
	{
		shouldConnect = false;
	} // visitATHROW
	
} // class ConnectionVisitor