Beispiel #1
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());
     }
   }
 }
Beispiel #2
0
  /**
   * Check that the set of <code>LocalInstance</code>s <code>localsUsed</code>, which is the set of
   * locals used in the inner class declared by <code>cb</code> are initialized before the class
   * declaration.
   */
  protected void checkLocalsUsedByInnerClass(
      FlowGraph graph, ClassBody cb, Set localsUsed, DataFlowItem dfIn, DataFlowItem dfOut)
      throws SemanticException {
    for (Iterator iter = localsUsed.iterator(); iter.hasNext(); ) {
      LocalInstance li = (LocalInstance) iter.next();
      MinMaxInitCount initCount = (MinMaxInitCount) dfOut.initStatus.get(li);
      if (!currCBI.localDeclarations.contains(li)) {
        // the local wasn't defined in this scope.
        currCBI.outerLocalsUsed.add(li);
      } else if (initCount == null || InitCount.ZERO.equals(initCount.getMin())) {
        // initCount will in general not be null, as the local variable
        // li is declared in the current class; however, if the inner
        // class is declared in the initializer of the local variable
        // declaration, then initCount could in fact be null, as we
        // leave the inner class before we have performed flowLocalDecl
        // for the local variable declaration.

        throw new SemanticException(
            "Local variable \""
                + li.name()
                + "\" must be initialized before the class "
                + "declaration.",
            cb.position());
      }
    }
  }
Beispiel #3
0
 static MinMaxInitCount join(MinMaxInitCount initCount1, MinMaxInitCount initCount2) {
   if (initCount1 == null) {
     return initCount2;
   }
   if (initCount2 == null) {
     return initCount1;
   }
   MinMaxInitCount t =
       new MinMaxInitCount(
           InitCount.min(initCount1.getMin(), initCount2.getMin()),
           InitCount.max(initCount1.getMax(), initCount2.getMax()));
   return t;
 }
Beispiel #4
0
  /**
   * The confluence operator is essentially the union of all of the inItems. However, if two or more
   * of the initCount maps from the inItems each have a MinMaxInitCounts entry for the same
   * VarInstance, the conflict must be resolved, by using the minimum of all mins and the maximum of
   * all maxs.
   */
  public Item confluence(List inItems, Term node, FlowGraph graph) {
    // Resolve any conflicts pairwise.
    Iterator iter = inItems.iterator();
    Map m = null;
    while (iter.hasNext()) {
      Item itm = (Item) iter.next();
      if (itm == BOTTOM) continue;
      if (m == null) {
        m = new HashMap(((DataFlowItem) itm).initStatus);
      } else {
        Map n = ((DataFlowItem) itm).initStatus;
        for (Iterator iter2 = n.entrySet().iterator(); iter2.hasNext(); ) {
          Map.Entry entry = (Map.Entry) iter2.next();
          VarInstance v = (VarInstance) entry.getKey();
          MinMaxInitCount initCount1 = (MinMaxInitCount) m.get(v);
          MinMaxInitCount initCount2 = (MinMaxInitCount) entry.getValue();
          m.put(v, MinMaxInitCount.join(initCount1, initCount2));
        }
      }
    }

    if (m == null) return BOTTOM;

    return new DataFlowItem(m);
  }
Beispiel #5
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  /** Check that the assignment to a local variable is correct. */
  protected void checkLocalAssign(
      FlowGraph graph, LocalAssign a, DataFlowItem dfIn, DataFlowItem dfOut)
      throws SemanticException {
    LocalInstance li = ((Local) a.left()).localInstance();
    if (!currCBI.localDeclarations.contains(li)) {
      throw new SemanticException(
          "Final local variable \"" + li.name() + "\" cannot be assigned to in an inner class.",
          a.position());
    }

    MinMaxInitCount initCount = (MinMaxInitCount) dfOut.initStatus.get(li);

    if (li.flags().isFinal() && InitCount.MANY.equals(initCount.getMax())) {
      throw new SemanticException(
          "variable \"" + li.name() + "\" might already have been assigned to", a.position());
    }
  }
Beispiel #6
0
 /**
  * Check that each static final field is initialized exactly once.
  *
  * @param cb The ClassBody of the class declaring the fields to check.
  * @throws SemanticException
  */
 protected void checkStaticFinalFieldsInit(ClassBody cb) throws SemanticException {
   // check that all static fields have been initialized exactly once.
   for (Iterator iter = currCBI.currClassFinalFieldInitCounts.entrySet().iterator();
       iter.hasNext(); ) {
     Map.Entry e = (Map.Entry) iter.next();
     if (e.getKey() instanceof FieldInstance) {
       FieldInstance fi = (FieldInstance) e.getKey();
       if (fi.flags().isStatic() && fi.flags().isFinal()) {
         MinMaxInitCount initCount = (MinMaxInitCount) e.getValue();
         if (InitCount.ZERO.equals(initCount.getMin())) {
           throw new SemanticException(
               "field \"" + fi.name() + "\" might not have been initialized", cb.position());
         }
       }
     }
   }
 }
Beispiel #7
0
  /**
   * Check that each non static final field has been initialized exactly once, taking into account
   * the fact that constructors may call other constructors.
   *
   * @param cb The ClassBody of the class declaring the fields to check.
   * @throws SemanticException
   */
  protected void checkNonStaticFinalFieldsInit(ClassBody cb) throws SemanticException {
    // for each non-static final field instance, check that all
    // constructors intialize it exactly once, taking into account constructor calls.
    for (Iterator iter = currCBI.currClassFinalFieldInitCounts.keySet().iterator();
        iter.hasNext(); ) {
      FieldInstance fi = (FieldInstance) iter.next();
      if (fi.flags().isFinal() && !fi.flags().isStatic()) {
        // the field is final and not static
        // it must be initialized exactly once.
        // navigate up through all of the the constructors
        // that this constructor calls.

        boolean fieldInitializedBeforeConstructors = false;
        MinMaxInitCount ic = (MinMaxInitCount) currCBI.currClassFinalFieldInitCounts.get(fi);
        if (ic != null && !InitCount.ZERO.equals(ic.getMin())) {
          fieldInitializedBeforeConstructors = true;
        }

        for (Iterator iter2 = currCBI.allConstructors.iterator(); iter2.hasNext(); ) {
          ConstructorDecl cd = (ConstructorDecl) iter2.next();
          ConstructorInstance ciStart = cd.constructorInstance();
          ConstructorInstance ci = ciStart;

          boolean isInitialized = fieldInitializedBeforeConstructors;

          while (ci != null) {
            Set s = (Set) currCBI.fieldsConstructorInitializes.get(ci);
            if (s != null && s.contains(fi)) {
              if (isInitialized) {
                throw new SemanticException(
                    "field \"" + fi.name() + "\" might have already been initialized",
                    cd.position());
              }
              isInitialized = true;
            }
            ci = (ConstructorInstance) currCBI.constructorCalls.get(ci);
          }
          if (!isInitialized) {
            throw new SemanticException(
                "field \"" + fi.name() + "\" might not have been initialized", ciStart.position());
          }
        }
      }
    }
  }
Beispiel #8
0
  /** Perform the appropriate flow operations for assignment to a local variable */
  protected Map flowLocalAssign(
      DataFlowItem inItem, FlowGraph graph, LocalAssign a, Set succEdgeKeys) {
    Local l = (Local) a.left();
    Map m = new HashMap(inItem.initStatus);
    MinMaxInitCount initCount = (MinMaxInitCount) m.get(l.localInstance());

    // initcount could be null if the local is defined in the outer
    // class, or if we have not yet seen its declaration (i.e. the
    // local is used in its own initialization)
    if (initCount == null) {
      initCount = new MinMaxInitCount(InitCount.ZERO, InitCount.ZERO);
    }

    initCount = new MinMaxInitCount(initCount.getMin().increment(), initCount.getMax().increment());

    m.put(l.localInstance(), initCount);
    return itemToMap(new DataFlowItem(m), succEdgeKeys);
  }
Beispiel #9
0
  /** Perform necessary actions upon seeing the ConstructorDecl <code>cd</code>. */
  protected void finishConstructorDecl(
      FlowGraph graph, ConstructorDecl cd, DataFlowItem dfIn, DataFlowItem dfOut) {
    ConstructorInstance ci = cd.constructorInstance();

    // we need to set currCBI.fieldsConstructorInitializes correctly.
    // It is meant to contain the non-static final fields that the
    // constructor ci initializes.
    //
    // Note that dfOut.initStatus contains only the MinMaxInitCounts
    // for _normal_ termination of the constructor (see the
    // method confluence). This means that if dfOut says the min
    // count of the initialization for a final non-static field
    // is one, and that is different from what is recoreded in
    // currCBI.currClassFinalFieldInitCounts (which is the counts
    // of the initializations performed by initializers), then
    // the constructor does indeed initialize the field.

    Set s = new HashSet();

    // go through every final non-static field in dfOut.initStatus
    Iterator iter = dfOut.initStatus.entrySet().iterator();
    while (iter.hasNext()) {
      Entry e = (Entry) iter.next();
      if (e.getKey() instanceof FieldInstance
          && ((FieldInstance) e.getKey()).flags().isFinal()
          && !((FieldInstance) e.getKey()).flags().isStatic()) {
        // we have a final non-static field
        FieldInstance fi = (FieldInstance) e.getKey();
        MinMaxInitCount initCount = (MinMaxInitCount) e.getValue();
        MinMaxInitCount origInitCount =
            (MinMaxInitCount) currCBI.currClassFinalFieldInitCounts.get(fi);
        if (initCount.getMin() == InitCount.ONE
            && (origInitCount == null || origInitCount.getMin() == InitCount.ZERO)) {
          // the constructor initialized this field
          s.add(fi);
        }
      }
    }
    if (!s.isEmpty()) {
      currCBI.fieldsConstructorInitializes.put(ci, s);
    }
  }
Beispiel #10
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  /** 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;
  }
Beispiel #11
0
 /** Check that the local variable <code>l</code> is used correctly. */
 protected void checkLocal(FlowGraph graph, Local l, DataFlowItem dfIn, DataFlowItem dfOut)
     throws SemanticException {
   if (!currCBI.localDeclarations.contains(l.localInstance())) {
     // it's a local variable that has not been declared within
     // this scope. The only way this can arise is from an
     // inner class that is not a member of a class (typically
     // a local class, or an anonymous class declared in a method,
     // constructor or initializer).
     // We need to check that it is a final local, and also
     // keep track of it, to ensure that it has been definitely
     // assigned at this point.
     currCBI.outerLocalsUsed.add(l.localInstance());
   } else {
     MinMaxInitCount initCount = (MinMaxInitCount) dfIn.initStatus.get(l.localInstance());
     if (initCount != null && InitCount.ZERO.equals(initCount.getMin())) {
       // the local variable may not have been initialized.
       // However, we only want to complain if the local is reachable
       if (l.reachable()) {
         throw new SemanticException(
             "Local variable \"" + l.name() + "\" may not have been initialized", l.position());
       }
     }
   }
 }