From 3fa5d0677ae7f1f8c210c5dc47164764c05446d0 Mon Sep 17 00:00:00 2001
From: Eduard Valeyev <eduard@valeyev.net>
Date: Mon, 23 Jun 2014 10:40:40 -0400
Subject: [PATCH] Related to #44 .... Range::rank() is now constexpr also
 (updated TWG::Range spec). Added test to text.C, but only clang++ accepts it.
 @shiozaki please check with your g++.

---
 btas/range.h  | 19 ++++++++++---------
 doc/range.dox |  2 +-
 test/test.C   |  9 +++++++++
 3 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/btas/range.h b/btas/range.h
index 9fa01385..ffa274e8 100644
--- a/btas/range.h
+++ b/btas/range.h
@@ -422,15 +422,6 @@ namespace btas {
         return Range1d<typename index_type::value_type>(*(std::begin(lobound_)+d), *(std::begin(upbound_)+d));
       }
 
-      /// Rank accessor
-
-      /// \return The rank (number of dimensions) of this range
-      /// \throw nothing
-      size_t rank() const {
-        using btas::rank;
-        return rank(lobound_);
-      }
-
       /// Range lobound coordinate accessor
 
       /// \return A \c size_array that contains the lower bound of this range
@@ -451,6 +442,16 @@ namespace btas {
         return upbound_;
       }
 
+      /// Rank accessor
+
+      /// \return The rank (number of dimensions) of this range
+      /// \throw nothing
+      //constexpr auto rank() const -> decltype(btas::rank(this->lobound())) {
+      constexpr size_t rank() const {
+        using btas::rank;
+        return rank(lobound_);
+      }
+
       /// Range size accessor
 
       /// \return A \c extent_type that contains the extent of each dimension
diff --git a/doc/range.dox b/doc/range.dox
index 767c8fcd..187f2383 100644
--- a/doc/range.dox
+++ b/doc/range.dox
@@ -147,7 +147,7 @@
     <td> \c rank() </td>
     <td> \c uint </td>
     <td> </td>
-    <td> returns the rank of Range; const </td>
+    <td> returns the rank of Range; const (and constexpr, if possible) </td>
    </tr>
 
    <tr>
diff --git a/test/test.C b/test/test.C
index 689fc084..e4743dc0 100644
--- a/test/test.C
+++ b/test/test.C
@@ -59,6 +59,7 @@ int main()
   // default (empty) Range
   Range x0;
   cout << "x0 = " << x0 << " area=" << x0.area() << endl;
+  assert(x0.rank() == 0);  // std::cout << "rank = 0" << std::endl;
 
   // Range initialized by extents of each dimension
   Range x1(3, 2, 3);
@@ -111,6 +112,14 @@ int main()
   Range x6 ({-1, -1, -1}, {2, 3, 4});
   cout << "x6 = " << x6 << " area=" << x6.area() << endl;
 
+  {
+    typedef RangeNd<CblasRowMajor, std::array<size_t, 3>> Range3d;
+    Range3d x;
+    cout << "Static 3-d Range: x7 = " << x << " area=" << x.area() << endl;
+    assert(x.rank() == 3);
+    static_assert(x.rank() == 3, "default Range rank");
+  }
+
   //////////////////////////////////////////////////////////////////////////////
   // Tensor tests
   //////////////////////////////////////////////////////////////////////////////