[Fb-contrib-commit] fb-contrib/src/com/mebigfatguy/fbcontrib/detect DateComparison.java,NONE,1.1

[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-serv11131/src/com/mebigfatguy/fbcontrib/detect

Added Files:
	DateComparison.java 
Log Message:
initial checkin - new DDC detector

--- NEW FILE: DateComparison.java ---
/*
 * fb-contrib - Auxilliary detectors for Java programs
 * Copyright (C) 2005-2006 Dave Brosius
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package com.mebigfatguy.fbcontrib.detect;

import org.apache.bcel.classfile.Method;

import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.StatelessDetector;
import edu.umd.cs.findbugs.visitclass.Constants2;

/**
 * Looks for inefficient comparison of Date objects using two comparisons when one would do.
 */
public class DateComparison extends BytecodeScanningDetector implements Constants2, StatelessDetector {

	private static final int SEEN_NOTHING = 0;
	private static final int SEEN_LOAD1_1 = 1;
	private static final int SEEN_LOAD1_2 = 2;
	private static final int SEEN_CMP_1 = 3;
	private static final int SEEN_IFNE = 4;
	private static final int SEEN_LOAD2_1 = 5;
	private static final int SEEN_LOAD2_2 = 6;
	private static final int SEEN_CMP_2 = 7;
	
    private BugReporter bugReporter;
    private int state;
    private int register1_1;
    private int register1_2;
    private int register2_1;
    private int register2_2;

    /**
     * constructs a DDC detector given the reporter to report bugs on
     * @param bugReporter the sync of bug reports
	 */
    public DateComparison(BugReporter bugReporter) {
        this.bugReporter = bugReporter;
    }

	/**
	 * clone this detector so that it can be a StatelessDetector
	 * 
	 * @return a clone of this object
	 */
	@Override
	public Object clone() throws CloneNotSupportedException {
		return super.clone();
	}
	
	
	/**
	 * overrides the visitor to reset the registers
	 * 
	 * @param obj the method of the currently parsed method
	 */
	@Override
	public void visit(Method obj) {
        state = SEEN_NOTHING;
        register1_1 = -1;
        register1_2 = -1;
        register2_1 = -1;
        register2_2 = -1;
        super.visit(obj);
    }

	/**
	 * overrides the visitor to look for double date compares using the same registers
	 * 
	 * @param seen the current opcode parsed.
	 */
	@Override
	public void sawOpcode(int seen) {
        switch (state) {
        	case SEEN_NOTHING:
        		if ((seen >= ALOAD_0) || (seen <= ALOAD_3))
        			register1_1 = seen - ALOAD_0;
        		else if (seen == ALOAD)
        			register1_1 = getRegisterOperand();
        			
        		if (register1_1 > -1)
        			state = SEEN_LOAD1_1;
        	break;
        	
        	case SEEN_LOAD1_1:
        		if ((seen >= ALOAD_0) || (seen <= ALOAD_3))
        			register1_2 = seen - ALOAD_0;
        		else if (seen == ALOAD)
        			register1_2 = getRegisterOperand();
        			
        		if (register1_2 > -1)
        			state = SEEN_LOAD1_2;
        		else
        			state = SEEN_NOTHING;
        	break;
        	
        	case SEEN_LOAD1_2:
        		if (seen == INVOKEVIRTUAL) {
        			String cls = getDottedClassConstantOperand();
        			if ((cls.equals("java.util.Date")) || (cls.equals("java.sql.Date"))) {
        				String methodName = getNameConstantOperand();
        				if (methodName.equals( "equals" )
        				||  methodName.equals( "after" )
        				||  methodName.equals( "before" )) {
        					state = SEEN_CMP_1;
        				}
        			}
        		}
        		if (state != SEEN_CMP_1)
        			state = SEEN_NOTHING;
        	break;
        	
        	case SEEN_CMP_1:
        		if (seen == IFNE)
        			state = SEEN_IFNE;
        		else
        			state = SEEN_NOTHING;
        	break;

			case SEEN_IFNE:
	    		if ((seen >= ALOAD_0) || (seen <= ALOAD_3))
	    			register2_1 = seen - ALOAD_0;
	    		else if (seen == ALOAD)
	    			register2_1 = getRegisterOperand();
	    			
	    		if (register2_1 > -1)
	    			state = SEEN_LOAD2_1;
	    		else
	    			state = SEEN_NOTHING;
	    	break;

			case SEEN_LOAD2_1:
	    		if ((seen >= ALOAD_0) || (seen <= ALOAD_3))
	    			register2_2 = seen - ALOAD_0;
	    		else if (seen == ALOAD)
	    			register2_2 = getRegisterOperand();
	    			
	    		if ((register2_2 > -1) 
	    		&&  ( ((register1_1 == register2_1) && (register1_2 == register2_2))
	    		    ||((register1_1 == register2_2) && (register1_2 == register2_1))))
	    				state = SEEN_LOAD2_2;
	    		else
	    			state = SEEN_NOTHING;
	    	break;
	    	
	    	case SEEN_LOAD2_2:
        		if (seen == INVOKEVIRTUAL) {
        			String cls = getDottedClassConstantOperand();
        			if ((cls.equals("java.util.Date")) || (cls.equals("java.sql.Date"))) {
        				String methodName = getNameConstantOperand();
        				if (methodName.equals( "equals" )
        				||  methodName.equals( "after" )
        				||  methodName.equals( "before" )) {
        					state = SEEN_CMP_2;
        				}
        			}
        		}
        		if (state != SEEN_CMP_2)
        			state = SEEN_NOTHING;
	    	break;
	    	
	    	case SEEN_CMP_2:
	    		if (seen == IFEQ) {
	    			bugReporter.reportBug(new BugInstance("DDC_DOUBLE_DATE_COMPARISON", NORMAL_PRIORITY)
								.addClassAndMethod(this)
								.addSourceLine(this));
	    		}
	    		state = SEEN_NOTHING;
	    	break;
        }
    }
}