    /* Soot - a J*va Optimization Framework
     * Copyright (C) 2003 Jennifer Lhotak
     *
     * 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.
     */

    import soot.*;
    import soot.tagkit.*;
    import soot.toolkits.graph.*;
    import java.util.*;
    import soot.toolkits.scalar.*;
    import soot.jimple.*;

    public class NullnessAnalysisColorer extends BodyTransformer {
        protected void internalTransform (Body b, String phaseName, Map options) {
            NullnessAnalysis analysis = new NullnessAnalysis
                (new CompleteUnitGraph(b));

            Iterator it = b.getUnits().iterator();

            while (it.hasNext()) {
                Stmt s = (Stmt)it.next();

                Iterator usesIt = s.getUseBoxes().iterator();
                FlowSet beforeSet = (FlowSet)analysis.getFlowBefore(s);

                while (usesIt.hasNext()) {
                    ValueBox vBox = (ValueBox)usesIt.next();
                    addColorTags(vBox, beforeSet, s, analysis);
                }

                Iterator defsIt = s.getDefBoxes().iterator();
                FlowSet afterSet = (FlowSet)analysis.getFallFlowAfter(s);

                while (defsIt.hasNext()){
                    ValueBox vBox = (ValueBox)defsIt.next();
                    addColorTags(vBox, afterSet, s, analysis);
                }
            }
        }

        private void addColorTags(ValueBox vBox, FlowSet set,
                                  Stmt s, NullnessAnalysis analysis) {
            Value val = vBox.getValue();
            if (val.getType() instanceof RefLikeType &&
                    ((ArraySparseSet)set).contains(val))
                vBox.addTag(new ColorTag(ColorTag.GREEN));
        }
    }