From 7866749a2a05e8edc694c9bb77f9c3d375147ae0 Mon Sep 17 00:00:00 2001
From: Frank Park <fpark12@icloud.com>
Date: Tue, 11 Apr 2017 01:09:31 -0400
Subject: [PATCH] move is_invocable to type_traits.h

---
 include/sqlpp11/type_traits.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/include/sqlpp11/type_traits.h b/include/sqlpp11/type_traits.h
index cf377f07..5e5056f6 100644
--- a/include/sqlpp11/type_traits.h
+++ b/include/sqlpp11/type_traits.h
@@ -533,6 +533,16 @@ namespace sqlpp
 
   template <typename Db>
   using serializer_context_of = typename serializer_context_of_impl<Db>::type;
+
+  template<typename F, typename... Args>
+  struct in_invocable
+  {
+    template<class U> static auto test(U* p) -> decltype((*p)(std::declval<Args>()...), void(), std::true_type());
+    template<class U> static auto test(...) -> decltype(std::false_type());
+
+    typedef decltype(test<F>(0)) type;
+    static constexpr bool value = decltype(test<F>(0))::value;
+  };
 }
 
 #endif