From 9c979fc03a87d4542629455983a0b07a4dc5cd72 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Mon, 5 Aug 2019 18:22:53 +0200
Subject: [PATCH] Missing op*() added

---
 doc/DESIGN.md                 | 12 +++++++++---
 src/include/units/quantity.h  | 15 +++++++++++++--
 test/unit_test/test_units.cpp |  4 +++-
 3 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/doc/DESIGN.md b/doc/DESIGN.md
index ee6fc03e..04fc23f8 100644
--- a/doc/DESIGN.md
+++ b/doc/DESIGN.md
@@ -258,14 +258,20 @@ public:
   [[nodiscard]] static constexpr quantity one() noexcept { return quantity(quantity_values<Rep>::one()); }
 
   template<Unit U1, Scalar Rep1, Unit U2, Scalar Rep2>
-      requires treat_as_floating_point<decltype(lhs.count() * rhs.count())> ||
-               (std::ratio_multiply<typename U1::ratio, typename U2::ratio>::den == 1)
+      requires std::Same<typename U1::dimension, dim_invert_t<typename U2::dimension>>
+  [[nodiscard]] constexpr Scalar operator*(const quantity<U1, Rep1>& lhs,
+                                           const quantity<U2, Rep2>& rhs);
+
+  template<Unit U1, Scalar Rep1, Unit U2, Scalar Rep2>
+      requires (!std::Same<typename U1::dimension, dim_invert_t<typename U2::dimension>>) &&
+               (treat_as_floating_point<decltype(lhs.count() * rhs.count())> ||
+                (std::ratio_multiply<typename U1::ratio, typename U2::ratio>::den == 1))
   [[nodiscard]] constexpr Quantity operator*(const quantity<U1, Rep1>& lhs,
                                              const quantity<U2, Rep2>& rhs);
 
   template<Scalar Rep1, typename U, typename Rep2>
   [[nodiscard]] constexpr Quantity operator/(const Rep1& v,
-                                             const quantity<U, Rep2>& q)
+                                             const quantity<U, Rep2>& q);
 
   template<Unit U1, Scalar Rep1, Unit U2, Scalar Rep2>
     requires std::Same<typename U1::dimension, typename U2::dimension>
diff --git a/src/include/units/quantity.h b/src/include/units/quantity.h
index 77bb3fb0..5d3d9471 100644
--- a/src/include/units/quantity.h
+++ b/src/include/units/quantity.h
@@ -277,11 +277,22 @@ namespace std::experimental::units {
     return q * v;
   }
 
+  template<Unit U1, Scalar Rep1, Unit U2, Scalar Rep2>
+  [[nodiscard]] constexpr Scalar operator*(const quantity<U1, Rep1>& lhs,
+                                           const quantity<U2, Rep2>& rhs)
+      requires std::Same<typename U1::dimension, dim_invert_t<typename U2::dimension>>
+  {
+    using common_rep = decltype(lhs.count() * rhs.count());
+    using ratio = ratio_multiply<typename U1::ratio, typename U2::ratio>;
+    return common_rep(lhs.count()) * common_rep(rhs.count()) * common_rep(ratio::num) / common_rep(ratio::den);
+  }
+
   template<Unit U1, Scalar Rep1, Unit U2, Scalar Rep2>
   [[nodiscard]] constexpr Quantity operator*(const quantity<U1, Rep1>& lhs,
                                              const quantity<U2, Rep2>& rhs)
-      requires treat_as_floating_point<decltype(lhs.count() * rhs.count())> ||
-               (std::ratio_multiply<typename U1::ratio, typename U2::ratio>::den == 1)
+      requires (!std::Same<typename U1::dimension, dim_invert_t<typename U2::dimension>>) &&
+               (treat_as_floating_point<decltype(lhs.count() * rhs.count())> ||
+                (std::ratio_multiply<typename U1::ratio, typename U2::ratio>::den == 1))
   {
     using dim = dimension_multiply_t<typename U1::dimension, typename U2::dimension>;
     using common_rep = decltype(lhs.count() * rhs.count());
diff --git a/test/unit_test/test_units.cpp b/test/unit_test/test_units.cpp
index dbe57911..c559d131 100644
--- a/test/unit_test/test_units.cpp
+++ b/test/unit_test/test_units.cpp
@@ -61,6 +61,7 @@ namespace {
   static_assert(1m == 1000mm);
   static_assert(1km + 1m == 1001m);
   static_assert(10km / 5km == 2);
+  static_assert(100mm / 5cm == 2);
   static_assert(10km / 2 == 5km);
 
   static_assert(1yd == 0.9144m);
@@ -77,10 +78,11 @@ namespace {
   // frequency
 
   static_assert(2 / 1s == 2Hz);
+  static_assert(120 / 1min == 2Hz);
   static_assert(1000 / 1s == 1kHz);
   static_assert(1 / 1ms == 1kHz);
   static_assert(3.2GHz == 3'200'000'000Hz);
-//  static_assert(10hz * 1min == 600);
+  static_assert(10Hz * 1min == 600);
 
   // force