Review

2

com/google/javascript/rhino/jstype/UnionTypeBuilder.java

reduceAlternatesWithoutUnion()

class UnionTypeBuilder {
  /**
   * Reduce the alternates into a non-union type.
   * If the alternates can't be accurately represented with a non-union
   * type, return null.
   */
  private JSType reduceAlternatesWithoutUnion() {
    if (isAllType) {
      return registry.getNativeType(ALL_TYPE);
    } else if (isNativeUnknownType) {
      if (areAllUnknownsChecked) {
        return registry.getNativeType(CHECKED_UNKNOWN_TYPE);
      } else {
        return registry.getNativeType(UNKNOWN_TYPE);
      }
    } else {
      int size = alternates.size();
      if (size > MAX_UNION_SIZE) {
        return registry.getNativeType(UNKNOWN_TYPE);
      } else if (size > 1) {
        return null;
      } else if (size == 1) {
        return alternates.iterator().next();
      } else {
        return registry.getNativeType(NO_TYPE);
      }
    }
  }

}