/* Soot - a J*va Optimization Framework
 * Copyright (C) 1997-2002 Raja Vallee-Rai
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library 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.
 */
/*
 * Modified by the Sable Research Group and others 1997-2002.
 * See the 'credits' file distributed with Soot for the complete list of
 * contributors.  (Soot is distributed at http://www.sable.mcgill.ca/soot)
 */
/* Reference Version: $SootVersion: 1.2.2.dev.6 $ */
package ptolemy.copernicus.kernel;

import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.TreeSet;

import soot.Timers;
import soot.toolkits.graph.DirectedGraph;
import soot.toolkits.scalar.FlowAnalysis;

/**
 *   Abstract class that provides the fixed point iteration functionality
 *   required by all ForwardFlowAnalyses.
 *
 */
public abstract class FastForwardFlowAnalysis extends FlowAnalysis {
    /** Construct the analysis from a DirectedGraph representation of a Body. */
    public FastForwardFlowAnalysis(DirectedGraph graph) {
        super(graph);
    }

    protected boolean isForward() {
        return true;
    }

    protected void doAnalysis() {
        // CHANGED
        final HashMap indexMap = new HashMap();
        TreeSet changedUnitsSet = new TreeSet(new Comparator() {
            public int compare(Object o1, Object o2) {
                Integer i1 = (Integer) indexMap.get(o1);
                Integer i2 = (Integer) indexMap.get(o2);
                return i1.compareTo(i2);
            }
        });

        int numNodes = graph.size();
        int numComputations = 0;
        int index = 0;
        // Set initial values and nodes to visit.
        {
            Iterator it = graph.iterator();

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

                indexMap.put(s, Integer.valueOf(index++));
                changedUnitsSet.add(s);

                unitToBeforeFlow.put(s, newInitialFlow());
                unitToAfterFlow.put(s, newInitialFlow());
            }
        }

        // ENDCHANGE
        customizeInitialFlowGraph();
        // Feng Qian: March 07, 2002
        // Set initial values for entry points
        {
            Iterator it = graph.getHeads().iterator();

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

                // this is a forward flow analysis
                unitToBeforeFlow.put(s, entryInitialFlow());
            }
        }
        // Perform fixed point flow analysis
        {
            Object previousAfterFlow = newInitialFlow();

            while (!changedUnitsSet.isEmpty()) {
                Object beforeFlow;
                Object afterFlow;

                Object s = changedUnitsSet.first();
                changedUnitsSet.remove(s);

                copy(unitToAfterFlow.get(s), previousAfterFlow);
                // Compute and store beforeFlow
                {
                    List preds = graph.getPredsOf(s);

                    beforeFlow = unitToBeforeFlow.get(s);

                    if (preds.size() == 1) {
                        copy(unitToAfterFlow.get(preds.get(0)), beforeFlow);
                    } else if (preds.size() != 0) {
                        Iterator predIt = preds.iterator();

                        copy(unitToAfterFlow.get(predIt.next()), beforeFlow);

                        while (predIt.hasNext()) {
                            Object otherBranchFlow = unitToAfterFlow.get(predIt
                                    .next());
                            merge(beforeFlow, otherBranchFlow, beforeFlow);
                        }
                    }
                }
                // Compute afterFlow and store it.
                {
                    afterFlow = unitToAfterFlow.get(s);
                    flowThrough(beforeFlow, s, afterFlow);
                    numComputations++;
                }

                // Update queue appropriately
                if (!afterFlow.equals(previousAfterFlow)) {
                    //            System.out.println("changed = " + s);
                    //System.out.println("from " + previousAfterFlow);
                    //System.out.println("  to " + afterFlow);
                    Iterator succIt = graph.getSuccsOf(s).iterator();

                    while (succIt.hasNext()) {
                        Object succ = succIt.next();

                        changedUnitsSet.add(succ);
                    }
                }
            }
        }

        // System.out.println(graph.getBody().getMethod().getSignature() + " numNodes: " + numNodes +
        //    " numComputations: " + numComputations + " avg: " + Main.truncatedOf((double) numComputations / numNodes, 2));
        Timers.v().totalFlowNodes += numNodes;
        Timers.v().totalFlowComputations += numComputations;
    }
}