コード例 #1
0
ファイル: JProgram.java プロジェクト: hammoum/gwt
  /**
   * Return the greatest lower bound of two types. That is, return the largest type that is a
   * subtype of both inputs.
   */
  public JReferenceType strongerType(JReferenceType type1, JReferenceType type2) {
    if (type1 == type2) {
      return type1;
    }

    if (type1 instanceof JNullType || type2 instanceof JNullType) {
      return JNullType.INSTANCE;
    }

    if (type1 instanceof JNonNullType != type2 instanceof JNonNullType) {
      // If either is non-nullable, the result should be non-nullable.
      return strongerType(type1.getNonNull(), type2.getNonNull());
    }

    if (typeOracle.canTriviallyCast(type1, type2)) {
      return type1;
    }

    if (typeOracle.canTriviallyCast(type2, type1)) {
      return type2;
    }

    // cannot determine a strong type, just return the first one (this makes two
    // "unrelated" interfaces work correctly in TypeTightener
    return type1;
  }
コード例 #2
0
ファイル: JProgram.java プロジェクト: hammoum/gwt
 public boolean isJavaScriptObject(JType type) {
   if (type instanceof JReferenceType && typeSpecialJavaScriptObject != null) {
     return typeOracle.canTriviallyCast((JReferenceType) type, typeSpecialJavaScriptObject);
   }
   return false;
 }
コード例 #3
0
ファイル: JProgram.java プロジェクト: hammoum/gwt
  /**
   * Return the least upper bound of two types. That is, the smallest type that is a supertype of
   * both types.
   */
  public JReferenceType generalizeTypes(JReferenceType type1, JReferenceType type2) {
    if (type1 == type2) {
      return type1;
    }

    if (type1 instanceof JNonNullType && type2 instanceof JNonNullType) {
      // Neither can be null.
      type1 = type1.getUnderlyingType();
      type2 = type2.getUnderlyingType();
      return generalizeTypes(type1, type2).getNonNull();
    } else if (type1 instanceof JNonNullType) {
      // type2 can be null, so the result can be null
      type1 = type1.getUnderlyingType();
    } else if (type2 instanceof JNonNullType) {
      // type1 can be null, so the result can be null
      type2 = type2.getUnderlyingType();
    }
    assert !(type1 instanceof JNonNullType);
    assert !(type2 instanceof JNonNullType);

    int classify1 = classifyType(type1);
    int classify2 = classifyType(type2);

    if (classify1 == IS_NULL) {
      return type2;
    }

    if (classify2 == IS_NULL) {
      return type1;
    }

    if (classify1 == classify2) {

      // same basic kind of type
      if (classify1 == IS_INTERFACE) {

        if (typeOracle.canTriviallyCast(type1, type2)) {
          return type2;
        }

        if (typeOracle.canTriviallyCast(type2, type1)) {
          return type1;
        }

        // unrelated
        return typeJavaLangObject;

      } else if (classify1 == IS_ARRAY) {

        JArrayType aType1 = (JArrayType) type1;
        JArrayType aType2 = (JArrayType) type2;
        int dims1 = aType1.getDims();
        int dims2 = aType2.getDims();

        int minDims = Math.min(dims1, dims2);
        /*
         * At a bare minimum, any two arrays generalize to an Object array with
         * one less dim than the lesser of the two; that is, int[][][][] and
         * String[][][] generalize to Object[][]. If minDims is 1, then they
         * just generalize to Object.
         */
        JReferenceType minimalGeneralType;
        if (minDims > 1) {
          minimalGeneralType = getTypeArray(typeJavaLangObject, minDims - 1);
        } else {
          minimalGeneralType = typeJavaLangObject;
        }

        if (dims1 == dims2) {

          // Try to generalize by leaf types
          JType leafType1 = aType1.getLeafType();
          JType leafType2 = aType2.getLeafType();

          if (!(leafType1 instanceof JReferenceType) || !(leafType2 instanceof JReferenceType)) {
            return minimalGeneralType;
          }

          /*
           * Both are reference types; the result is the generalization of the
           * leaf types combined with the number of dims; that is, Foo[] and
           * Bar[] generalize to X[] where X is the generalization of Foo and
           * Bar.
           */
          JReferenceType leafRefType1 = (JReferenceType) leafType1;
          JReferenceType leafRefType2 = (JReferenceType) leafType2;

          /**
           * Never generalize arrays to arrays of {@link JNonNullType} as null array initialization
           * is not accounted for in {@link TypeTightener}.
           */
          JReferenceType leafGeneralization =
              generalizeTypes(leafRefType1, leafRefType2).getUnderlyingType();
          return getTypeArray(leafGeneralization, dims1);

        } else {

          // Conflicting number of dims

          // int[][] and Object[] generalize to Object[]
          JArrayType lesser = dims1 < dims2 ? aType1 : aType2;
          if (lesser.getLeafType() == typeJavaLangObject) {
            return lesser;
          }

          // Totally unrelated
          return minimalGeneralType;
        }

      } else {

        assert (classify1 == IS_CLASS);
        JClassType class1 = (JClassType) type1;
        JClassType class2 = (JClassType) type2;

        /*
         * see how far each type is from object; walk the one who's farther up
         * until they're even; then walk them up together until they meet (worst
         * case at Object)
         */
        int distance1 = countSuperTypes(class1);
        int distance2 = countSuperTypes(class2);
        for (; distance1 > distance2; --distance1) {
          class1 = class1.getSuperClass();
        }

        for (; distance1 < distance2; --distance2) {
          class2 = class2.getSuperClass();
        }

        while (class1 != class2) {
          class1 = class1.getSuperClass();
          class2 = class2.getSuperClass();
        }

        return class1;
      }
    } else {

      // different kinds of types
      int lesser = Math.min(classify1, classify2);
      int greater = Math.max(classify1, classify2);

      JReferenceType tLesser = classify1 < classify2 ? type1 : type2;
      JReferenceType tGreater = classify1 > classify2 ? type1 : type2;

      if (lesser == IS_INTERFACE && greater == IS_CLASS) {

        // just see if the class implements the interface
        if (typeOracle.canTriviallyCast(tGreater, tLesser)) {
          return tLesser;
        }

        // unrelated
        return typeJavaLangObject;

      } else if (greater == IS_ARRAY
          && ((tLesser == typeJavaLangCloneable) || (tLesser == typeJavaIoSerializable))) {
        return tLesser;
      } else {

        // unrelated: the best commonality between an interface and array, or
        // between an array and a class is Object
        return typeJavaLangObject;
      }
    }
  }