/*
 * FindBugs - Find Bugs in Java programs
 * Copyright (C) 2003-2007 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.classfile.Code;

import edu.umd.cs.findbugs.BugAccumulator;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.ba.SignatureParser;
import edu.umd.cs.findbugs.bcel.OpcodeStackDetector;

/**
 * @author alison
 */
public class BooleanReturnNull extends OpcodeStackDetector {

    BugAccumulator bugAccumulator;

    public BooleanReturnNull(BugReporter bugReporter) {
        this.bugAccumulator = new BugAccumulator(bugReporter);
    }

    @Override
    public void visit(Code code) {
        String s = getMethodSig();
        SignatureParser sp = new SignatureParser(s);
        // Check to see if the method has Boolean return type
        boolean interesting = "Ljava/lang/Boolean;".equals(sp.getReturnTypeSignature());
        if (interesting) {
            super.visit(code); // make callbacks to sawOpcode for all opcodes
            bugAccumulator.reportAccumulatedBugs();
        }
    }

    /*
     * (non-Javadoc)
     * 
     * @see edu.umd.cs.findbugs.bcel.OpcodeStackDetector#sawOpcode(int)
     */
    @Override
    public void sawOpcode(int seen) {
        if (seen == ARETURN && getPrevOpcode(1) == ACONST_NULL)
            bugAccumulator.accumulateBug(new BugInstance(this, "NP_BOOLEAN_RETURN_NULL",
                    getMethodName().startsWith("is") ? HIGH_PRIORITY : NORMAL_PRIORITY).addClassAndMethod(this), this);

    }

}