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A Java Optimization Framework

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package soot.jimple.spark.solver;

/*-
 * #%L
 * Soot - a J*va Optimization Framework
 * %%
 * Copyright (C) 2002 Ondrej Lhotak
 * %%
 * This program 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 program 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 General Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public
 * License along with this program.  If not, see
 * .
 * #L%
 */

import java.util.HashSet;

import soot.jimple.spark.pag.Node;
import soot.jimple.spark.pag.PAG;
import soot.jimple.spark.pag.VarNode;

/**
 * Performs a pseudo-topological sort on the VarNodes in a PAG.
 * 
 * @author Ondrej Lhotak
 */

public class TopoSorter {
  /** Actually perform the topological sort on the PAG. */
  public void sort() {
    for (VarNode v : pag.getVarNodeNumberer()) {
      dfsVisit(v);
    }
    visited = null;
  }

  public TopoSorter(PAG pag, boolean ignoreTypes) {
    this.pag = pag;
    this.ignoreTypes = ignoreTypes;
    // this.visited = new NumberedSet( pag.getVarNodeNumberer() );
    this.visited = new HashSet();
  }

  /* End of public methods. */
  /* End of package methods. */

  protected boolean ignoreTypes;
  protected PAG pag;
  protected int nextFinishNumber = 1;
  protected HashSet visited;

  protected void dfsVisit(VarNode n) {
    if (visited.contains(n)) {
      return;
    }
    visited.add(n);
    Node[] succs = pag.simpleLookup(n);
    for (Node element : succs) {
      if (ignoreTypes || pag.getTypeManager().castNeverFails(n.getType(), element.getType())) {
        dfsVisit((VarNode) element);
      }
    }
    n.setFinishingNumber(nextFinishNumber++);
  }
}