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-serv8800/src/com/mebigfatguy/fbcontrib/detect

Added Files:
	ClassEnvy.java 
Log Message:
Initial Checkin: Class Envy Detector

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

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.JavaClass;
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.OpcodeStack;
import edu.umd.cs.findbugs.StatelessDetector;
import edu.umd.cs.findbugs.ba.ClassContext;


public class ClassEnvy extends BytecodeScanningDetector implements StatelessDetector
{
	private static final String ENVY_PERCENT_PROPERTY = "fb-contrib.ce.percentt";
	private BugReporter bugReporter;
	private OpcodeStack stack;
	private String packageName;
	private String clsName;
	private Map<String, Integer> clsMethodCount;
	private int thisClsMethodCount;
	private double envyPercent = 0.80;
	
	public ClassEnvy(BugReporter bugReporter) {
		this.bugReporter = bugReporter;
		stack = new OpcodeStack();
		String percent = System.getProperty(ENVY_PERCENT_PROPERTY);
		if (percent != null) {
			try {
				envyPercent = Double.valueOf(percent);
			} catch (NumberFormatException nfe) {
				//Stick with original
			}
		}
	}
	
	public Object clone() throws CloneNotSupportedException {
		return super.clone();
	}
	
	public void visitClassContext(ClassContext classContext) {
		JavaClass cls = classContext.getJavaClass();
		packageName = cls.getPackageName();
		clsName = cls.getClassName();
		super.visitClassContext(classContext);
	}
	
	public void visitCode(Code obj) {
		stack.resetForMethodEntry(this);
		clsMethodCount = new HashMap<String, Integer>();
		thisClsMethodCount = 0;
		super.visitCode(obj);
		
		String bestEnvy = null;
		double bestPercent = -1.0;
		Iterator<Map.Entry<String,Integer>> it = clsMethodCount.entrySet().iterator();
		while (it.hasNext()) {
			Map.Entry<String,Integer> entry = it.next();
			
			Integer mc = entry.getValue();
			if (mc.intValue() < 3)
				continue;
			
			double percent = ((double)mc.intValue()) / ((double)(mc.intValue() + thisClsMethodCount));
			if (percent > bestPercent) {
				bestPercent = percent;
				bestEnvy = entry.getKey();
			}
		}
		
		if (bestPercent > envyPercent) {
			bugReporter.reportBug( new BugInstance( this, "CE_CLASS_ENVY", NORMAL_PRIORITY)
				.addClass(this)
				.addMethod(this)
				.addSourceLine(this, 0)
				.addString(bestEnvy));
		}
	}
	
	public void sawOpcode(int seen) {
		try {
			if ((seen == INVOKEVIRTUAL)
			||  (seen == INVOKEINTERFACE)
			||  (seen == INVOKESTATIC)) {
				String calledClass = getClassConstantOperand().replace('/', '.');
				if (calledClass.startsWith("java.")
				||  calledClass.startsWith("javax."))
					return;
				
				if (seen == INVOKEINTERFACE) {
					int parmCount = Type.getArgumentTypes(this.getMethodSig()).length;
					try {
						if (stack.getStackDepth() > parmCount) {
							OpcodeStack.Item itm = stack.getStackItem(parmCount);
							JavaClass jcls = itm.getJavaClass();
							if (jcls != null)
								calledClass = itm.getJavaClass().getClassName();
						}
					} catch (ClassNotFoundException cnfe) {
						bugReporter.reportMissingClass(cnfe);
					}
				}
				
				String calledPackage = getPackageName(calledClass);
				
				if (calledClass.equals(clsName))
					thisClsMethodCount++;
				else {
					if (similarPackages(calledPackage, packageName, 2)) {
						Integer cnt = clsMethodCount.get(calledClass);
						if (cnt == null) {
							cnt = new Integer(1);
							clsMethodCount.put(calledClass, cnt);
						} else {
							clsMethodCount.put(calledClass, new Integer(cnt.intValue() + 1));
						}
					}
				}
			}
		} finally {
			stack.sawOpcode(this, seen);
		}
	}
	
	private String getPackageName(String className) {
		int dotPos = className.lastIndexOf(".");
		if (dotPos < 0)
			return "";
		return className.substring(0, dotPos);
	}

	private boolean similarPackages(String packName1, String packName2, int depth) {
		if (depth == 0)
			return true;
		
		int dot1 = packName1.indexOf(".");
		int dot2 = packName2.indexOf(".");
		if (dot1 < 0) {
			if (dot2 < 0)
				return true;
			return false;
		} else if (dot2 < 0)
			return false;
		
		String s1 = packName1.substring(0, dot1);
		String s2 = packName2.substring(0, dot2);
		
		if (!s1.equals(s2))
			return false;
		
		return similarPackages(packName1.substring(dot1+1), packName2.substring(dot2+1), depth-1);
	}
}