From e40a5d631c7f6531b99c9feccc48102d8af24910 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Thu, 1 Sep 2022 12:16:47 +0200
Subject: [PATCH] feat: solid angle support added

---
 src/core/CMakeLists.txt                      |   2 +
 src/core/include/units/generic/solid_angle.h | 104 +++++++++++++++++++
 test/unit_test/static/angle_test.cpp         |  11 +-
 3 files changed, 115 insertions(+), 2 deletions(-)
 create mode 100644 src/core/include/units/generic/solid_angle.h

diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index 431f258a..56f462af 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -45,6 +45,7 @@ add_library(
     include/units/exponent.h
     include/units/generic/angle.h
     include/units/generic/dimensionless.h
+    include/units/generic/solid_angle.h
     include/units/kind.h
     include/units/magnitude.h
     include/units/math.h
@@ -83,6 +84,7 @@ endif()
 if(DEFINED ${projectPrefix}DOWNCAST_MODE)
     set(downcast_mode_options OFF ON AUTO)
     list(FIND downcast_mode_options "${${projectPrefix}DOWNCAST_MODE}" downcast_mode)
+
     if(downcast_mode EQUAL -1)
         message(FATAL_ERROR
                     "'${projectPrefix}DOWNCAST_MODE' should be one of ${downcast_mode_options} ('${${projectPrefix}DOWNCAST_MODE}' received)"
diff --git a/src/core/include/units/generic/solid_angle.h b/src/core/include/units/generic/solid_angle.h
new file mode 100644
index 00000000..eff9d388
--- /dev/null
+++ b/src/core/include/units/generic/solid_angle.h
@@ -0,0 +1,104 @@
+// The MIT License (MIT)
+//
+// Copyright (c) 2018 Mateusz Pusz
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+#pragma once
+
+// IWYU pragma: begin_exports
+#include <units/generic/angle.h>
+#include <units/quantity.h>
+#include <units/reference.h>
+#include <units/symbol_text.h>
+// IWYU pragma: end_exports
+
+#include <units/isq/si/prefixes.h>
+
+namespace units {
+
+struct steradian : named_unit<steradian, "sr"> {};
+
+template<Unit U = steradian>
+struct dim_solid_angle : derived_dimension<dim_solid_angle<U>, U, exponent<dim_angle<>, 2>> {};
+
+struct square_degree : derived_scaled_unit<square_degree, dim_solid_angle<>, degree> {};
+
+template<typename T>
+concept SolidAngle = QuantityOfT<T, dim_solid_angle>;
+
+template<UnitOf<dim_solid_angle<>> U, Representation Rep = double>
+using solid_angle = quantity<dim_solid_angle<>, U, Rep>;
+
+#ifndef UNITS_NO_LITERALS
+
+inline namespace literals {
+
+// sr
+constexpr auto operator"" _q_sr(unsigned long long l)
+{
+  gsl_ExpectsAudit(std::in_range<std::int64_t>(l));
+  return solid_angle<steradian, std::int64_t>(static_cast<std::int64_t>(l));
+}
+constexpr auto operator"" _q_sr(long double l) { return solid_angle<steradian, long double>(l); }
+
+// deg2
+constexpr auto operator"" _q_deg2(unsigned long long l)
+{
+  gsl_ExpectsAudit(std::in_range<std::int64_t>(l));
+  return solid_angle<square_degree, std::int64_t>(static_cast<std::int64_t>(l));
+}
+constexpr auto operator"" _q_deg2(long double l) { return solid_angle<square_degree, long double>(l); }
+
+}  // namespace literals
+
+#endif  // UNITS_NO_LITERALS
+
+#ifndef UNITS_NO_REFERENCES
+
+namespace solid_angle_references {
+
+inline constexpr auto sr = reference<dim_solid_angle<>, steradian>{};
+inline constexpr auto deg2 = reference<dim_solid_angle<>, square_degree>{};
+
+}  // namespace solid_angle_references
+
+namespace references {
+
+using namespace solid_angle_references;
+
+}  // namespace references
+
+#endif  // UNITS_NO_REFERENCES
+
+}  // namespace units
+
+#ifndef UNITS_NO_ALIASES
+
+namespace units::aliases::inline solid_angle {
+
+template<Representation Rep = double>
+using sr = units::solid_angle<units::steradian, Rep>;
+
+template<Representation Rep = double>
+using deg2 = units::solid_angle<units::square_degree, Rep>;
+
+}  // namespace units::aliases::inline solid_angle
+
+#endif  // UNITS_NO_ALIASES
diff --git a/test/unit_test/static/angle_test.cpp b/test/unit_test/static/angle_test.cpp
index ccbd692c..4abc679e 100644
--- a/test/unit_test/static/angle_test.cpp
+++ b/test/unit_test/static/angle_test.cpp
@@ -21,18 +21,20 @@
 // SOFTWARE.
 
 #include <units/generic/angle.h>
+#include <units/generic/solid_angle.h>
 #include <numbers>
 
 namespace {
 
+// plane angle
+
 using namespace units::references;
+using namespace units::literals;
 
 static_assert(360 * deg == 1 * rot);
 static_assert(400 * grad == 1 * rot);
 static_assert(std::numbers::pi * 2 * rad == 1. * rot);
 
-using namespace units::literals;
-
 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));
@@ -42,4 +44,9 @@ 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.));
 
+// solid angle
+
+static_assert(1_q_rad * 1_q_rad == 1_q_sr);
+static_assert(1_q_deg * 1_q_deg == 1_q_deg2);
+
 }  // namespace