feat: gradian support added

example/aliases/experimental_angle.cpp

@@ -40,4 +40,5 @@ int main()
   std::cout << angle << '\n';
   std::cout << quantity_cast<rotation>(angle) << '\n';
   std::cout << quantity_cast<degree>(angle) << '\n';
+  std::cout << quantity_cast<gradian>(angle) << '\n';
 }

example/literals/experimental_angle.cpp

@@ -40,4 +40,5 @@ int main()
   std::cout << angle << '\n';
   std::cout << quantity_cast<rotation>(angle) << '\n';
   std::cout << quantity_cast<degree>(angle) << '\n';
+  std::cout << quantity_cast<gradian>(angle) << '\n';
 }

example/references/experimental_angle.cpp

@@ -49,4 +49,5 @@ int main()
   std::cout << angle << '\n';
   std::cout << quantity_cast<rotation>(angle) << '\n';
   std::cout << quantity_cast<degree>(angle) << '\n';
+  std::cout << quantity_cast<gradian>(angle) << '\n';
 }

src/core/include/units/generic/angle.h

@@ -35,6 +35,7 @@ namespace units {
 struct radian : named_unit<radian, "rad"> {};
 struct rotation : named_scaled_unit<rotation, "rot", mag<2>() * mag_pi, radian> {};
 struct degree : named_scaled_unit<degree, basic_symbol_text{"°", "deg"}, mag<ratio{1, 360}>(), rotation> {};
+struct gradian : named_scaled_unit<gradian, basic_symbol_text{"ᵍ", "grad"}, mag<ratio{1, 400}>(), rotation> {};
 
 template<Unit U = radian>
 struct dim_angle : base_dimension<"A", U> {};
@@ -73,6 +74,14 @@ constexpr auto operator"" _q_deg(unsigned long long l)
 }
 constexpr auto operator"" _q_deg(long double l) { return angle<degree, long double>(l); }
 
+// grad
+constexpr auto operator"" _q_grad(unsigned long long l)
+{
+  gsl_ExpectsAudit(std::in_range<std::int64_t>(l));
+  return angle<gradian, std::int64_t>(static_cast<std::int64_t>(l));
+}
+constexpr auto operator"" _q_grad(long double l) { return angle<gradian, long double>(l); }
+
 }  // namespace literals
 
 #endif  // UNITS_NO_LITERALS
@@ -84,6 +93,7 @@ namespace angle_references {
 inline constexpr auto rad = reference<dim_angle<>, radian>{};
 inline constexpr auto rot = reference<dim_angle<>, rotation>{};
 inline constexpr auto deg = reference<dim_angle<>, degree>{};
+inline constexpr auto grad = reference<dim_angle<>, gradian>{};
 
 }  // namespace angle_references
 
@@ -107,6 +117,8 @@ template<Representation Rep = double>
 using rot = units::angle<units::rotation, Rep>;
 template<Representation Rep = double>
 using deg = units::angle<units::degree, Rep>;
+template<Representation Rep = double>
+using grad = units::angle<units::gradian, Rep>;
 
 }  // namespace units::aliases::inline angle
 

test/unit_test/static/angle_test.cpp

@@ -27,26 +27,19 @@ namespace {
 
 using namespace units::references;
 
-static_assert(360. * deg == 1. * rot);
 static_assert(360 * deg == 1 * rot);
+static_assert(400 * grad == 1 * rot);
 static_assert(std::numbers::pi * 2 * rad == 1. * rot);
 
-}  // namespace
-
-namespace {
-
 using namespace units::literals;
 
-static_assert(360._q_deg == 1._q_rot);
 static_assert(360_q_deg == 1_q_rot);
+static_assert(400_q_grad == 1_q_rot);
 static_assert(std::numbers::pi * quantity_cast<double>(2._q_rad) == quantity_cast<double>(1._q_rot));
 
-}  // namespace
-
-namespace {
-
 static_assert(units::aliases::deg<>(360.) == units::aliases::rot<>(1.));
 static_assert(units::aliases::deg<int>(360) == units::aliases::rot<int>(1));
+static_assert(units::aliases::grad<int>(400) == units::aliases::rot<int>(1));
 static_assert(std::numbers::pi * units::aliases::rad<>(2.) == units::aliases::rot<>(1.));
 
 }  // namespace