From 2dcb315ce6bf156af889beb1cffb9c0c8cb7850f Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Mon, 12 Dec 2016 17:07:53 +1100
Subject: [PATCH] region: prefer constexpr functions over static variables

---
 region.cpp      | 27 +++------------------------
 region.hpp      |  4 ++--
 region.ipp      | 26 ++++++++++++++++++++++++++
 test/region.cpp | 10 +++++-----
 4 files changed, 36 insertions(+), 31 deletions(-)

diff --git a/region.cpp b/region.cpp
index 0203010d..5ee285d6 100644
--- a/region.cpp
+++ b/region.cpp
@@ -232,8 +232,8 @@ util::region<S,T>::intersection (region<S,T> rhs) const
     point_t a, b;
 
     for (size_t i = 0; i < S; ++i) {
-        a[i] = max (p[i],        rhs.p[i]);
-        b[i] = min (p[i] + e[i], rhs.p[i] + rhs.e[i]);
+        a[i] = util::max (p[i],        rhs.p[i]);
+        b[i] = util::min (p[i] + e[i], rhs.p[i] + rhs.e[i]);
 
         if (b[i] < a[i])
             throw std::logic_error ("no overlap");
@@ -336,28 +336,7 @@ util::region<S,T>::operator== (region rhs) const
 }
 
 
-///----------------------------------------------------------------------------
-/// The largest specifiable finite region.
-///
-/// Starts at half the minimum value to allow the width to cover some positive
-/// range rather than just cancelling out the lowest value for signed types.
-///
-/// Specifically does not allow infinities. Use/define INFINITE when required.
-
-template <size_t S, typename T>
-const util::region<S,T>
-util::region<S,T>::MAX (
-    util::point<S,T> {std::numeric_limits<T>::lowest () / 2},
-    util::extent<S,T> {std::numeric_limits<T>::max ()}
-);
-
-
-template  <size_t S, typename T>
-const util::region<S,T>
-util::region<S,T>::UNIT (util::point<S,T>{0}, util::extent<S,T>{1});
-
-
-//-----------------------------------------------------------------------------
+///////////////////////////////////////////////////////////////////////////////
 template <size_t S, typename T>
 std::ostream&
 util::operator<< (std::ostream &os, const util::region<S,T> &rhs) {
diff --git a/region.hpp b/region.hpp
index 44c2764a..b707a2bd 100644
--- a/region.hpp
+++ b/region.hpp
@@ -105,8 +105,8 @@ namespace util {
             { return !(*this == rhs); }
 
         // Utility constants
-        static const region<S,T> MAX;
-        static const region<S,T> UNIT;
+        static constexpr region<S,T> max  (void);
+        static constexpr region<S,T> unit (void);
 
         void sanity (void) const;
     };
diff --git a/region.ipp b/region.ipp
index e0e9f062..2209f445 100644
--- a/region.ipp
+++ b/region.ipp
@@ -31,3 +31,29 @@ util::region<S,T>::cast (void) const
         e.template cast<U> ()
     };
 }
+
+
+///////////////////////////////////////////////////////////////////////////////
+template <size_t S, typename T>
+constexpr
+util::region<S,T>
+util::region<S,T>::max (void)
+{
+    return {
+        util::point <S,T> {std::numeric_limits<T>::lowest () / 2},
+        util::extent<S,T> {std::numeric_limits<T>::max ()}
+    };
+}
+
+
+//-----------------------------------------------------------------------------
+template <size_t S, typename T>
+constexpr
+util::region<S,T>
+util::region<S,T>::unit (void)
+{
+    return {
+        point_t::origin (),
+        extent_t {1}
+    };
+}
diff --git a/test/region.cpp b/test/region.cpp
index 66efb720..9f4a26d0 100644
--- a/test/region.cpp
+++ b/test/region.cpp
@@ -23,13 +23,13 @@ main (int, char **)
         tap.expect (!a.intersects (b), "simple 2d intersection");
     }
 
-    tap.expect (util::region2d::MAX.intersects (util::region2d::UNIT), "maximal region2d intersection");
-    tap.expect (util::region2f::MAX.intersects (util::region2f::UNIT), "maximal region2f intersection");
+    tap.expect (util::region2d::max ().intersects (util::region2d::unit ()), "maximal region2d intersection");
+    tap.expect (util::region2f::max ().intersects (util::region2f::unit ()), "maximal region2f intersection");
 
-    tap.expect_eq (util::region2d::UNIT.area (), 1.0,  "unit region2d area");
-    tap.expect_eq (util::region2f::UNIT.area (), 1.0f, "unit region2f area");
+    tap.expect_eq (util::region2d::unit ().area (), 1.0,  "unit region2d area");
+    tap.expect_eq (util::region2f::unit ().area (), 1.0f, "unit region2f area");
 
-    util::point2u p0 { 0 };
+    util::point2u  p0 { 0 };
     util::extent2u e0 { 2 };
 
     tap.expect (util::region2u (p0, e0).includes (util::point2u {1, 1}), "unsigned region centre inclusion");