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BBQ.java

package ca.mcgill.sable.soot.coffi;

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Jimple, a 3-address code Java(TM) bytecode representation.        *
 * Copyright (C) 1997, 1998 Raja Vallee-Rai (kor@sable.mcgill.ca)    *
 * All rights reserved.                                              *
 *                                                                   *
 * This work was done as a project of the Sable Research Group,      *
 * School of Computer Science, McGill University, Canada             *
 * (http://www.sable.mcgill.ca/).  It is understood that any         *
 * modification not identified as such is not covered by the         *
 * preceding statement.                                              *
 *                                                                   *
 * This work 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 work 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.                                      *
 *                                                                   *
 * Java is a trademark of Sun Microsystems, Inc.                     *
 *                                                                   *
 * To submit a bug report, send a comment, or get the latest news on *
 * this project and other Sable Research Group projects, please      *
 * visit the web site: http://www.sable.mcgill.ca/                   *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Coffi, a bytecode parser for the Java(TM) language.               *
 * Copyright (C) 1996, 1997 Clark Verbrugge (clump@sable.mcgill.ca). *
 * All rights reserved.                                              *
 *                                                                   *
 * This work was done as a project of the Sable Research Group,      *
 * School of Computer Science, McGill University, Canada             *
 * (http://www.sable.mcgill.ca/).  It is understood that any         *
 * modification not identified as such is not covered by the         *
 * preceding statement.                                              *
 *                                                                   *
 * This work 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 work 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.                                      *
 *                                                                   *
 * Java is a trademark of Sun Microsystems, Inc.                     *
 *                                                                   *
 * To submit a bug report, send a comment, or get the latest news on *
 * this project and other Sable Research Group projects, please      *
 * visit the web site: http://www.sable.mcgill.ca/                   *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
 Reference Version
 -----------------
 This is the latest official version on which this file is based.
 The reference version is: $CoffiVersion: 1.1 $
                           $SootVersion: 1.beta.4 $

 Change History
 --------------
 A) Notes:

 Please use the following template.  Most recent changes should
 appear at the top of the list.

 - Modified on [date (March 1, 1900)] by [name]. [(*) if appropriate]
   [description of modification].

 Any Modification flagged with "(*)" was done as a project of the
 Sable Research Group, School of Computer Science,
 McGill University, Canada (http://www.sable.mcgill.ca/).

 You should add your copyright, using the following template, at
 the top of this file, along with other copyrights.

 *                                                                   *
 * Modifications by [name] are                                       *
 * Copyright (C) [year(s)] [your name (or company)].  All rights     *
 * reserved.                                                         *
 *                                                                   *

 B) Changes:

 - Modified on November 2, 1998 by Raja Vallee-Rai (kor@sable.mcgill.ca) (*)
   Repackaged all source files and performed extensive modifications.
   First initial release of Soot.

 - Modified on 15-Jun-1998 by Raja Vallee-Rai (kor@sable.mcgill.ca). (*)
   First internal release (Version 0.1).
*/

import java.util.Vector;
import java.util.Enumeration;
import java.util.NoSuchElementException;

/** A queue of BasicBlocks.
 * @author Clark Verbrugge
 * @see BasicBlock
 */
final class BBQ {

   private Vector q = new Vector();

   /** Empties the queue of all blocks (and resets their <i>inq</i> flags). */
   public void clear() {
      BasicBlock b;
      for (Enumeration e = q.elements();e.hasMoreElements();) {
         b = (BasicBlock)(e.nextElement());
         b.inq = false;
      }
      q.removeAllElements();
   }   
   /** Answers whether a block is in the queue or not.
    * @param BasicBlock in question.
    * @return <i>true</i> if it is, <i>false</i> if it ain't.
    * @see BasicBlock#inq
    */
   public boolean contains(BasicBlock b) { return b.inq; }   
   /** Answers whether the queue is empty
    * @return <i>true</i> if it is, <i>false</i> if it ain't.
    */
   public boolean isEmpty() { return q.isEmpty(); }   
   /** Removes the first block in the queue (and resets its <i>inq</i> flag).
    * @return BasicBlock which was first.
    * @exception java.util.NoSuchElementException if the queue is empty.
    * @see BasicBlock#inq
    */
   public BasicBlock pull() throws NoSuchElementException {
      if(q.size()==0)
         throw new
            NoSuchElementException("Pull from empty BBQ");
      BasicBlock b = (BasicBlock)(q.firstElement());
      q.removeElementAt(0);
      b.inq = false;
      return b;
   }   
   /** Adds a block to the end of the queue, but only if its <i>inq</i> flag is false.
    * @param b the Basic Block in question.
    * @see BasicBlock#inq
    */
   public void push(BasicBlock b) {
      if (b.inq!=true) {  // ensure only in queue once...
         b.inq = true;
         q.addElement(b);
      }
   }   
   /** Answers the size of the queue.
    * @return size of the queue.
    */
   public int size() { return q.size(); }   
}

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