fb-contrib-commit

[Dave B. <dbr...@us...>]

Update of /cvsroot/fb-contrib/fb-contrib/src/com/mebigfatguy/fbcontrib/detect
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv28921/src/com/mebigfatguy/fbcontrib/detect

Added Files:
	FinalParameters.java 
Log Message:
Initial Checkin: FinalParameters

--- NEW FILE: FinalParameters.java ---
package com.mebigfatguy.fbcontrib.detect;

import java.util.HashSet;
import java.util.Set;

import org.apache.bcel.Constants;
import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.LocalVariable;
import org.apache.bcel.classfile.LocalVariableTable;
import org.apache.bcel.classfile.Method;
import org.apache.bcel.generic.Type;

import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.StatelessDetector;

public class FinalParameters extends BytecodeScanningDetector implements StatelessDetector
{
	private BugReporter bugReporter;
	private Set<Integer> changedParms;
	private int parmCount;
	private boolean isStatic;
	private boolean isAbstract;
	
	public FinalParameters(BugReporter bugReporter) {
		this.bugReporter = bugReporter;
	}
	
	public Object clone() throws CloneNotSupportedException {
		return super.clone();
	}
	
	public void visitMethod(Method obj) {
		isStatic = (obj.getAccessFlags() & Constants.ACC_STATIC) != 0;
		isAbstract = (obj.getAccessFlags() & Constants.ACC_ABSTRACT) != 0;
		parmCount = Type.getArgumentTypes(obj.getSignature()).length;
		super.visitMethod(obj);
	}
	
	public void visitCode(Code obj) {
		if (isAbstract)
			return;
		
		changedParms = new HashSet<Integer>();
		super.visitCode(obj);
		for (int i = 0; i < parmCount; i++) {
			if (changedParms.remove(new Integer(i)))
				continue;
			
			int reg;
			if (!isStatic)
				reg = i + 1;
			else
				reg = i;
			
			String parmName = getRegisterName(obj, reg);
			bugReporter.reportBug( new BugInstance( this, "FP_FINAL_PARAMETERS", LOW_PRIORITY)
				.addClass(this)
				.addMethod(this)
				.addSourceLine(this, 0)
				.addString(parmName));
		}
	}
	
	public void sawOpcode(int seen) {
		if ((seen == ASTORE) || ((seen >= ASTORE_0) && (seen <= ASTORE_3))) {
			int parm = getAStoreParameter(seen);
			if (parm >= 0)
				changedParms.add(new Integer(parm));
		}
	}
	
	private String getRegisterName(Code obj, int reg) {
		LocalVariableTable lvt = obj.getLocalVariableTable();
		if (lvt != null) {
			LocalVariable lv = lvt.getLocalVariable(reg, 0);
			if (lv != null)
				return lv.getName();
		}
		return String.valueOf(reg);
	}
	
	private int getAStoreParameter(int seen) {
		int reg;
		if (seen == ASTORE)
			reg = getRegisterOperand();
		else
			reg = seen - ASTORE_0;
		
		if (!isStatic)
			reg--;
		
		if (reg >= parmCount)
			reg = -1;
		
		return reg;
		
	}

}