From 4ba818bb7819825e7bd1bfa21a70a20dec6cd863 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Tue, 8 Oct 2019 21:20:06 +0200
Subject: [PATCH] quantity_cast_impl refactored to use compile time branching
 rather than concepts

---
 src/include/units/quantity.h | 32 ++++++++++++++------------------
 1 file changed, 14 insertions(+), 18 deletions(-)

diff --git a/src/include/units/quantity.h b/src/include/units/quantity.h
index b0ea1def..7cd558ad 100644
--- a/src/include/units/quantity.h
+++ b/src/include/units/quantity.h
@@ -93,18 +93,16 @@ namespace units {
     template<typename To, typename CR, typename CRep, bool NumIsOne = false, bool DenIsOne = false>
     struct quantity_cast_impl {
       template<typename Q>
-      requires treat_as_floating_point<CRep>
       static constexpr To cast(const Q& q)
       {
-        return To(static_cast<To::rep>(static_cast<CRep>(q.count()) * (static_cast<CRep>(CR::num) /
-                                       static_cast<CRep>(CR::den))));
-      }
-      template<typename Q>
-      requires !treat_as_floating_point<CRep>
-      static constexpr To cast(const Q& q)
-      {
-        return To(static_cast<To::rep>(static_cast<CRep>(q.count()) * static_cast<CRep>(CR::num) /
-                                       static_cast<CRep>(CR::den)));
+        if constexpr(treat_as_floating_point<CRep>) {
+          return To(static_cast<To::rep>(static_cast<CRep>(q.count()) * (static_cast<CRep>(CR::num) /
+                                         static_cast<CRep>(CR::den))));
+        }
+        else {
+          return To(static_cast<To::rep>(static_cast<CRep>(q.count()) * static_cast<CRep>(CR::num) /
+                                        static_cast<CRep>(CR::den)));
+        }
       }
     };
 
@@ -120,16 +118,14 @@ namespace units {
     template<typename To, typename CR, typename CRep>
     struct quantity_cast_impl<To, CR, CRep, true, false> {
       template<Quantity Q>
-      requires treat_as_floating_point<CRep>
       static constexpr To cast(const Q& q)
       {
-        return To(static_cast<To::rep>(static_cast<CRep>(q.count()) * (CRep{1} / static_cast<CRep>(CR::den))));
-      }
-      template<Quantity Q>
-      requires !treat_as_floating_point<CRep>
-      static constexpr To cast(const Q& q)
-      {
-        return To(static_cast<To::rep>(static_cast<CRep>(q.count()) / static_cast<CRep>(CR::den)));
+        if constexpr(treat_as_floating_point<CRep>) {
+          return To(static_cast<To::rep>(static_cast<CRep>(q.count()) * (CRep{1} / static_cast<CRep>(CR::den))));
+        }
+        else {
+          return To(static_cast<To::rep>(static_cast<CRep>(q.count()) / static_cast<CRep>(CR::den)));
+        }
       }
     };