refactor(search_family): address comments 3

Signed-off-by: Stepan Bagritsevich <[email protected]>

src/core/string_or_view.h

@@ -65,6 +65,10 @@ class StringOrView {
       val_ = std::string{std::get<std::string_view>(val_)};
   }
 
+  bool empty() const {
+    return visit([](const auto& s) { return s.empty(); }, val_);
+  }
+
  private:
   std::variant<std::string_view, std::string> val_;
 };

src/server/search/doc_index.h

@@ -110,21 +110,21 @@ class SearchField {
 
  private:
   bool HasNewAlias() const {
-    return new_alias_.has_value();
+    return !new_alias_.empty();
   }
 
   std::string_view NameView() const {
     return name_.view();
   }
 
   std::string_view AliasView() const {
-    return new_alias_.value().view();
+    return new_alias_.view();
   }
 
  private:
   StringOrView name_;
   bool is_short_name_;
-  std::optional<StringOrView> new_alias_;
+  StringOrView new_alias_;
 };
 
 using SearchFieldsList = std::vector<SearchField>;