예제 #1
0
 /**
  * Determine if we are interested in this field on the basis of the target of the field. To wit,
  * if the field is static, then the target of the field must be the current class; if the field is
  * not static then the target must be "this".
  */
 protected boolean isFieldsTargetAppropriate(Field f) {
   if (f.fieldInstance().flags().isStatic()) {
     ClassType containingClass = (ClassType) currCBI.currCodeDecl.codeInstance().container();
     return containingClass.equals(f.fieldInstance().container());
   } else {
     return (f.target() instanceof Special && Special.THIS.equals(((Special) f.target()).kind()));
   }
 }
예제 #2
0
 /** Check that the assignment to a field is correct. */
 protected void checkFieldAssign(
     FlowGraph graph, FieldAssign a, DataFlowItem dfIn, DataFlowItem dfOut)
     throws SemanticException {
   Field f = (Field) a.left();
   FieldInstance fi = f.fieldInstance();
   if (fi.flags().isFinal()) {
     if ((currCBI.currCodeDecl instanceof ConstructorDecl
             || currCBI.currCodeDecl instanceof Initializer)
         && isFieldsTargetAppropriate(f)) {
       // we are in a constructor or initializer block and
       // if the field is static then the target is the class
       // at hand, and if it is not static then the
       // target of the field is this.
       // So a final field in this situation can be
       // assigned to at most once.
       MinMaxInitCount initCount = (MinMaxInitCount) dfOut.initStatus.get(fi);
       if (InitCount.MANY.equals(initCount.getMax())) {
         throw new SemanticException(
             "field \"" + fi.name() + "\" might already have been assigned to", a.position());
       }
     } else {
       // not in a constructor or intializer, or the target is
       // not appropriate. So we cannot assign
       // to a final field at all.
       throw new SemanticException(
           "Cannot assign a value " + "to final field \"" + fi.name() + "\"", a.position());
     }
   }
 }
  protected NodeVisitor enterCall(Node n) throws SemanticException {
    if (n instanceof FieldDecl) {
      FieldDecl fd = (FieldDecl) n;

      FwdReferenceChecker frc = (FwdReferenceChecker) this.copy();
      frc.inInitialization = true;
      frc.inStaticInit = fd.flags().flags().isStatic();

      frc.declaredFields = new HashSet<FieldDef>(declaredFields);
      declaredFields.add(fd.fieldDef());
      return frc;
    } else if (n instanceof Initializer) {
      FwdReferenceChecker frc = (FwdReferenceChecker) this.copy();
      frc.inInitialization = true;
      frc.inStaticInit = ((Initializer) n).flags().flags().isStatic();
      return frc;
    } else if (n instanceof FieldAssign) {
      FwdReferenceChecker frc = (FwdReferenceChecker) this.copy();
      return frc;
    } else if (n instanceof Field) {
      if (inInitialization) {
        // we need to check if this is an illegal fwd reference.
        Field f = (Field) n;

        // an illegal fwd reference if a usage of an instance
        // (resp. static) field occurs in an instance (resp. static)
        // initialization, and the innermost enclosing class or
        // interface of the usage is the same as the container of
        // the field, and we have not yet seen the field declaration.
        //
        // In addition, if a field is not accessed as a simple name,
        // then all is ok

        ClassType currentClass = context().currentClass();
        StructType fContainer = f.fieldInstance().container();

        if (inStaticInit == f.fieldInstance().flags().isStatic()
            && currentClass.typeEquals(fContainer, context)
            && !declaredFields.contains(f.fieldInstance().def())
            && f.isTargetImplicit()) {
          throw new SemanticException("Illegal forward reference", f.position());
        }
      }
    }
    return this;
  }
예제 #4
0
  /** Perform the appropriate flow operations for assignment to a field */
  protected Map flowFieldAssign(
      DataFlowItem inItem, FlowGraph graph, FieldAssign a, Set succEdgeKeys) {
    Field f = (Field) a.left();
    FieldInstance fi = f.fieldInstance();

    if (fi.flags().isFinal() && isFieldsTargetAppropriate(f)) {
      // this field is final and the target for this field is
      // appropriate for what we are interested in.
      Map m = new HashMap(inItem.initStatus);
      MinMaxInitCount initCount = (MinMaxInitCount) m.get(fi);
      // initCount may be null if the field is defined in an
      // outer class.
      if (initCount != null) {
        initCount =
            new MinMaxInitCount(initCount.getMin().increment(), initCount.getMax().increment());
        m.put(fi, initCount);
        return itemToMap(new DataFlowItem(m), succEdgeKeys);
      }
    }
    return null;
  }