//
// Copyright (C) 2006 United States Government as represented by the
// Administrator of the National Aeronautics and Space Administration
// (NASA).  All Rights Reserved.
//
// This software is distributed under the NASA Open Source Agreement
// (NOSA), version 1.3.  The NOSA has been approved by the Open Source
// Initiative.  See the file NOSA-1.3-JPF at the top of the distribution
// directory tree for the complete NOSA document.
//
// THE SUBJECT SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY
// KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
// LIMITED TO, ANY WARRANTY THAT THE SUBJECT SOFTWARE WILL CONFORM TO
// SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
// A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT
// THE SUBJECT SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT
// DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SUBJECT SOFTWARE.
//
package gov.nasa.jpf.vm;

import cmu.conditional.One;
import de.fosd.typechef.featureexpr.FeatureExpr;
import gov.nasa.jpf.JPFException;


/**
 * field info for object fields
 */
public class ReferenceFieldInfo extends SingleSlotFieldInfo {
  int init;  //  = MJIEnv.NULL; // not required for MJIEnv.NULL = 0
  
  String sInit; // <2do> pcm - just a temporary quirk to init from string literals
                // check if there are other non-object reference inits

  public ReferenceFieldInfo (String name, String type, int modifiers) {
    super(name, type, modifiers);
  }

  public String valueToString (Fields f) {
    int i = f.getIntValue(storageOffset).getValue();
    if (i == MJIEnv.NULL) {
      return "null";
    } else {
      return (VM.getVM().getHeap().get(i)).toString();
    }
  }

  public boolean isReference () {
    return true;
  }

  public Class<? extends ChoiceGenerator<?>> getChoiceGeneratorType() {
    return ReferenceChoiceGenerator.class;
  }

  public boolean isArrayField () {
    return ci.isArray;
  }

  public void setConstantValue (Object constValue){
    // <2do> pcm - check what other constants we might encounter, this is most
    // probably not just used for Strings.
    // Besides the type issue, there is an even bigger problem with identities.
    // For instance, all String refs initialized via the same string literal
    // inside a single classfile are in fact refering to the same object. This
    // means we have to keep a registry (hashtab) with string-literal created
    // String objects per ClassInfo, and use this when we assign or init
    // String references.
    // For the sake of progress, we ignore this for now, but have to come back
    // to it because it violates the VM spec

    if (constValue instanceof String){
      cv = constValue;
      sInit = (String)constValue;
    } else {
      throw new JPFException ("unsupported reference initialization: " + constValue);
    }
  }

  public void initialize (FeatureExpr ctx, ElementInfo ei, ThreadInfo ti) {
    int ref = init;
    if (sInit != null) {
      VM vm = ti.getVM();
      Heap heap = vm.getHeap();
      ref = heap.newString(ctx, sInit, ti).getObjectRef();
    }
    ei.getFields().setReferenceValue(ctx, storageOffset, new One<>(ref));
  }

  public Object getValueObject (Fields f){
    int i = f.getIntValue(storageOffset).getValue();
    if (i == MJIEnv.NULL) {
      return null;
    } else {
      Heap heap = VM.getVM().getHeap();
      return heap.get(i);
    }
  }
}