DF_AbstractCell.java

/*
 *  This file is part of the Jikes RVM project (http://jikesrvm.org).
 *
 *  This file is licensed to You under the Eclipse Public License (EPL);
 *  You may not use this file except in compliance with the License. You
 *  may obtain a copy of the License at
 *
 *      http://www.opensource.org/licenses/eclipse-1.0.php
 *
 *  See the COPYRIGHT.txt file distributed with this work for information
 *  regarding copyright ownership.
 */
package org.jikesrvm.compilers.opt.dfsolver;

import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;

import org.jikesrvm.compilers.opt.util.GraphNode;

/**
 * Represents a single lattice cell in a dataflow system.
 */
public abstract class DF_AbstractCell implements DF_LatticeCell {
  /**
   * Set of DF_Equations which use this lattice cell.
   */
  private final HashSet<DF_Equation> uses;
  /**
   * Set of DF_Equations which define this lattice cell.
   */
  private final HashSet<DF_Equation> defs;

  /**
   * Default Constructor
   */
  public DF_AbstractCell() {
    uses = new HashSet<DF_Equation>(1);
    defs = new HashSet<DF_Equation>(1);
  }

  /**
   * This constructor bounds the initial capacity to save space.
   * @param capacity the initial capacity of the "uses" set
   */
  public DF_AbstractCell(int capacity) {
    uses = new HashSet<DF_Equation>(capacity);
    defs = new HashSet<DF_Equation>(capacity);
  }

  @Override
  public Iterator<DF_Equation> getUses() {
    return uses.iterator();
  }

  @Override
  public Iterator<DF_Equation> getDefs() {
    return defs.iterator();
  }

  @Override
  public void addUse(DF_Equation eq) {
    uses.add(eq);
  }

  @Override
  public void addDef(DF_Equation eq) {
    defs.add(eq);
  }

  @Override
  public Enumeration<GraphNode> inNodes() {
    return new Enumeration<GraphNode>() {
      private final Iterator<DF_Equation> i = defs.iterator();

      @Override
      public boolean hasMoreElements() {
        return i.hasNext();
      }

      @Override
      public GraphNode nextElement() {
        return i.next();
      }
    };
  }

  @Override
  public Enumeration<GraphNode> outNodes() {
    return new Enumeration<GraphNode>() {
      private final Iterator<DF_Equation> i = uses.iterator();

      @Override
      public boolean hasMoreElements() {
        return i.hasNext();
      }

      @Override
      public GraphNode nextElement() {
        return i.next();
      }
    };
  }

  /**
   * Field used for GraphNode interface.  TODO: is this needed?
   */
  private int index;

  /**
   * Implementation of GraphNode interface.
   */
  @Override
  public void setIndex(int i) {
    index = i;
  }

  @Override
  public int getIndex() {
    return index;
  }

}