示例#1
0
  JSType getGreatestSubtypeHelper(JSType that) {
    if (that.isRecordType()) {
      RecordType thatRecord = that.toMaybeRecordType();
      RecordTypeBuilder builder = new RecordTypeBuilder(registry);
      builder.setSynthesized(true);

      // The greatest subtype consists of those *unique* properties of both
      // record types. If any property conflicts, then the NO_TYPE type
      // is returned.
      for (String property : getOwnPropertyNames()) {
        if (thatRecord.hasProperty(property)
            && !thatRecord.getPropertyType(property).isInvariant(getPropertyType(property))) {
          return registry.getNativeObjectType(JSTypeNative.NO_TYPE);
        }

        builder.addProperty(property, getPropertyType(property), getPropertyNode(property));
      }

      for (String property : thatRecord.getOwnPropertyNames()) {
        if (!hasProperty(property)) {
          builder.addProperty(
              property, thatRecord.getPropertyType(property), thatRecord.getPropertyNode(property));
        }
      }

      return builder.build();
    }

    JSType greatestSubtype = registry.getNativeType(JSTypeNative.NO_OBJECT_TYPE);
    JSType thatRestrictedToObj =
        registry.getNativeType(JSTypeNative.OBJECT_TYPE).getGreatestSubtype(that);
    if (!thatRestrictedToObj.isEmptyType()) {
      // In this branch, the other type is some object type. We find
      // the greatest subtype with the following algorithm:
      // 1) For each property "x" of this record type, take the union
      //    of all classes with a property "x" with a compatible property type.
      //    and which are a subtype of {@code that}.
      // 2) Take the intersection of all of these unions.
      for (String propName : getOwnPropertyNames()) {
        JSType propType = getPropertyType(propName);
        UnionTypeBuilder builder = new UnionTypeBuilder(registry);
        for (ObjectType alt : registry.getEachReferenceTypeWithProperty(propName)) {
          JSType altPropType = alt.getPropertyType(propName);
          if (altPropType != null
              && !alt.isEquivalentTo(this)
              && alt.isSubtype(that)
              && propType.isInvariant(altPropType)) {
            builder.addAlternate(alt);
          }
        }
        greatestSubtype = greatestSubtype.getLeastSupertype(builder.build());
      }
    }
    return greatestSubtype;
  }
 /** Gets the type of {@code this} in this function. */
 @Override
 public JSType getTypeOfThis() {
   return typeOfThis.isEmptyType()
       ? registry.getNativeObjectType(JSTypeNative.UNKNOWN_TYPE)
       : typeOfThis;
 }