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FGActionArrayRef.java

package edu.ksu.cis.bandera.bofa;

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Bandera, a Java(TM) analysis and transformation toolkit           *
 * Copyright (C) 1998, 1999                                          *
 * John Hatcliff (hatcliff@cis.ksu.edu)
 * All rights reserved.                                              *
 *                                                                   *
 * This work was done as a project in the SAnToS Laboratory,         *
 * Department of Computing and Information Sciences, Kansas State    *
 * University, USA (http://www.cis.ksu.edu/santos).                  *
 * 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 toolkit; 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 SAnToS projects, please visit the web-site *
 *                http://www.cis.ksu.edu/santos                      *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

import ca.mcgill.sable.util.*;
import ca.mcgill.sable.soot.*;
import ca.mcgill.sable.soot.jimple.*;
import java.util.Hashtable;

/*
 * FGActionArrayRef.java
 * $Id: FGActionArrayRef.java,v 1.1.1.1 2002/01/24 03:42:07 pserver Exp $
 */

/**
 * This class describes the action to taken when new values arrive at the base
 * position of an array reference that appears on the RHS of an assignment
 * statement.
 *
 * For every value variant that flows into the AST Node annotated by this
 * action, we want to find the corresponding array variant node, and hook it
 * into the flowgraph so that all values flowing out of the memory cells
 * abstracted by the array variant flow into the AST Node annotated by this
 * action.
 *
 * @author <A HREF="http://www.cis.ksu.edu/~hatcliff">John Hatcliff</A>
 * @author
 * <a href="http://www.cis.ksu.edu/~rvprasad">Venkatesh Prasad Ranganath</a>
 * @version $Name:  $($Revision: 1.1.1.1 $)
 */
public class FGActionArrayRef implements FGAction
{
    /** 
     * Array reference AST node.
     */
    private FGNode arrayRefNode;

    /** 
     * Set of array variants that have been connected into the flow graph for
     * this node.  
     */
    private Set installedArrayVariants;
    
    /** 
     * Class token corresponding to the array type of the array in context.
     */
    private ClassTokenArray refClassTokenArray;
    
    /** 
     * MethodVariant in which the array reference occurs. 
     */
    private MethodVariant methodVariant;
    
    /* Eventually, we will have the method name here as well, and parameter
       passing will be more complicated */

    /**
     * Constructor for the class.
     *
     * @param refClassTokenArray the class token generated by the type in
     * the array ref AST node
     *
     * @param arrayRefNode the array reference AST node
     * @param methodVariant the method variant enclosing the reference node.
     */
    public FGActionArrayRef(ClassTokenArray refClassTokenArray,
                            FGNode arrayRefNode, MethodVariant methodVariant) 
    {
        this.refClassTokenArray     = refClassTokenArray;
        this.arrayRefNode           = arrayRefNode;
        this.installedArrayVariants = new HashSet();
        this.methodVariant = methodVariant; 
    }
    /**
     * Hooks in the flow graph node associated with the array variant into the
     * graph as a producer node.  The array variant is the values in the
     * incoming set.
     * 
     * @param values triggered the action.
     * @see FGActionArrayStore#doAction FGActionArrayStore.doAction
     */
    public void doAction(FASet values)
    {
        ClassToken      classToken;
        ClassTokenArray classTokenArray;
        ArrayVariant    arrayVariant;

        /* Iterate through the given set of value variants */
        for(Iterator i = values.iterator(); i.hasNext();) {
            ValueVariant valueVariant = (ValueVariant) i.next();

            /* First, extract the class token from the value variant.
               If the class token is not an array then we have a 
               type-checking error.  Such errors may actually be due
               to imprecision in the analysis.  I have not observed this,
               but the possibility exists and is mentioned in Grove's thesis.
               For now, we will raise an exception if such a thing happens.

               If the class token is an array class we could also type check
               with the array class given by refClassTokenArray.  Ignore
               this for now.

               If the class token is an array class, then call the 
               array variant manager to select the appropriate array
               variant.  For now, let's lookup the array variant using the 
               ClassToken in the value variant.

               If the array variant is not already installed here, 
               - hook the node abstracting the contents of the array 
               into the flowgraph.
               - generate work to move ALL values
               at the array variant node along to array ref AST node.
            */

            classToken = valueVariant.getClassToken();

            if (classToken instanceof ClassTokenArray) {
                classTokenArray  = ((ClassTokenArray) classToken);
            } else {
                throw new RuntimeException 
                    ("BOFA: non-array object flowing  into  array ref site");
            }
        
            /* Select the appropriate array variant */
            arrayVariant = 
                ArrayVariantManager.select(classToken, valueVariant); 

            if (!installedArrayVariants.contains(arrayVariant)) {
                // hook array variant into the flowgraph 
                FGNode arrayNode = arrayVariant.getNode();
               
                /* make value flow arc from the array cell summary to the
                 * array reference AST node */
                FGNode.makeArc(arrayNode, arrayRefNode);                
                FA.workList.insert(new FGWorkSendVals(arrayNode.getValues(),
                                              arrayRefNode));
                
                /* Add the method variant to the list of variants installed
                 * at this node. */
                installedArrayVariants.add(arrayVariant);
            } /* end: if */

        } /* end: for each valueVariant */
    }
}

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