From 34aed6c74da69fd1ca8d03c723e37bace87a1b4f Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Fri, 11 Sep 2020 13:36:04 +1000
Subject: [PATCH] strongdef: add `is_strongdef` type_trait

---
 strongdef.hpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/strongdef.hpp b/strongdef.hpp
index cc02511c..0e010a4e 100644
--- a/strongdef.hpp
+++ b/strongdef.hpp
@@ -76,6 +76,18 @@ namespace cruft::strongdef {
     };
 
 
+    template <typename>
+    struct is_strongdef : public std::false_type {};
+
+
+    template <typename TagT, typename ValueT>
+    struct is_strongdef<strongdef::index<TagT, ValueT>> : public std::true_type {};
+
+
+    template <typename ValueT>
+    constexpr bool is_strongdef_v = is_strongdef<ValueT>::value;
+
+
     template <typename TagT, typename T>
     std::ostream&
     operator<< (std::ostream &os, index<TagT,T> const &val)