diff --git a/toml/acceptor.hpp b/toml/acceptor.hpp
index d19a04b..8104142 100644
--- a/toml/acceptor.hpp
+++ b/toml/acceptor.hpp
@@ -365,6 +365,16 @@ using is_literal_multiline_string =
         is_repeat_of<is_charactor<charT, '\''>, 3>
     >;
 
+template<typename charT>
+using is_string =
+    is_one_of<
+        is_basic_inline_string<charT>,
+        is_basic_multiline_string<charT>,
+        is_literal_inline_string<charT>,
+        is_literal_multiline_string<charT>
+    >;
+
+
 template<typename charT>
 using is_sign = is_one_of<is_charactor<charT, '+'>, is_charactor<charT, '-'>>;
 template<typename charT>
@@ -494,6 +504,15 @@ using is_offset_date_time =
         is_offset<charT>
     >;
 
+template<typename charT>
+using is_datetime =
+    is_one_of<
+        is_offset_date_time<charT>,
+        is_local_date_time<charT>,
+        is_local_date<charT>,
+        is_local_time<charT>
+    >;
+
 template<typename charT>
 using is_fundamental_type =
     is_one_of<