comparatoridiom.java

A static analysis tool to find bugs in Java programs

/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 2003,2004 University of Maryland
 * 
 * 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 edu.umd.cs.findbugs.detect;

import org.apache.bcel.Repository;
import org.apache.bcel.classfile.Field;
import org.apache.bcel.classfile.JavaClass;

import edu.umd.cs.findbugs.DeepSubtypeAnalysis;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.Detector;
import edu.umd.cs.findbugs.ba.ClassContext;
import edu.umd.cs.findbugs.util.ClassName;
import edu.umd.cs.findbugs.visitclass.PreorderVisitor;

public class ComparatorIdiom extends PreorderVisitor implements Detector {

	BugReporter bugReporter;

	public ComparatorIdiom(BugReporter bugReporter) {
		this.bugReporter = bugReporter;
	}

	public void visitClassContext(ClassContext classContext) {
		classContext.getJavaClass().accept(this);
	}


	@Override
	public void visit(JavaClass obj) {
		try {
			if (Repository.instanceOf(obj, "java.util.Comparator")
					&& !ClassName.isAnonymous(getClassName())
					&& !Repository.instanceOf(obj, "java.io.Serializable")) {
				int priority = NORMAL_PRIORITY;
				if (obj.isInterface() || obj.isAbstract()) {
					priority = LOW_PRIORITY;
				} else {
				double easilySerializable = 1.0;
				for(Field f : obj.getFields()) {
					try {
					String signature = f.getSignature();
					char firstChar = signature.charAt(0);
					if (firstChar == 'L' || firstChar == '[')
						easilySerializable *= DeepSubtypeAnalysis.isDeepSerializable(signature);
					} catch (ClassNotFoundException e) {
						easilySerializable = 0.0;
						break;
					}
				}

				if (easilySerializable < 0.9) priority = LOW_PRIORITY;
				int lastDollar = getClassName().lastIndexOf('$');
				if (lastDollar > 0 && Character.isDigit(getClassName().charAt(lastDollar+1)))
					priority = LOW_PRIORITY;
				}
				bugReporter
						.reportBug(new BugInstance(this,
								"SE_COMPARATOR_SHOULD_BE_SERIALIZABLE",
								priority).addClass(this));

			}
		} catch (ClassNotFoundException e) {
			// ignore it
		}
	}

	public void report() {

	}
}