From b67a99ee4e8a031a1ecaef3aa3cd8dfc4d3945c2 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Thu, 23 Mar 2017 14:36:39 +1100
Subject: [PATCH] coord: add arity query function

---
 coord/ops.hpp | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/coord/ops.hpp b/coord/ops.hpp
index 800fb1bb..dcf0afa6 100644
--- a/coord/ops.hpp
+++ b/coord/ops.hpp
@@ -87,6 +87,27 @@ namespace util {
     constexpr bool
     is_coord_v = is_coord<K>::value;
 
+
+    ///////////////////////////////////////////////////////////////////////////
+    template <typename T>
+    constexpr
+    std::enable_if_t<is_coord_v<T>, std::size_t>
+    arity (void)
+    {
+        return T::dimension;
+    }
+
+
+    //-------------------------------------------------------------------------
+    template <typename T>
+    constexpr
+    std::enable_if_t<std::is_arithmetic<T>::value, std::size_t>
+    arity (void)
+    {
+        return 1;
+    }
+
+
     ///////////////////////////////////////////////////////////////////////////
     // vector operators
 #define ELEMENT_OP(OP)                                  \