message: Add Mixed::is_unresolved_link()
diff: @@ -172,6 +172,7 @@ public:
  ObjLink get_link() const;
  bool is_null() const;
  + bool is_unresolved_link() const;
  int compare(const Mixed& b) const;
  bool operator==(const Mixed& other) const
  {
  @@ -484,6 +485,20 @@ inline bool Mixed::is_null() const
  return (m_type == 0);
  }
  +inline bool Mixed::is_unresolved_link() const
  +{
  + if (is_null()) {
  + return false;
  + }
  + else if (get_type() == type_TypedLink) {
  + return get<ObjLink>().is_unresolved();
  + }
  + else if (get_type() == type_Link) {
  + return get<ObjKey>().is_unresolved();
  + }
  + return false;
  +}
  +
  std::ostream& operator<<(std::ostream& out, const Mixed& m);
  } // namespace realm
  