From f0cf99457424dd7b3cc1bf6007bff42b97b3421b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johel=20Ernesto=20Guerrero=20Pe=C3=B1a?=
 <johelegp@gmail.com>
Date: Wed, 30 Aug 2023 10:28:30 -0400
Subject: [PATCH] feat: add module `mp_units`

---
 src/CMakeLists.txt                            | 14 +++++
 .../include/mp-units/bits/fmt_hacks.h         |  2 +-
 .../mp-units/bits/external/type_list.h        |  1 +
 src/core/include/mp-units/quantity_spec.h     | 15 +----
 .../include/mp-units/quantity_spec_macro.h    | 13 +++++
 src/mp-units.cpp                              | 58 +++++++++++++++++++
 src/utility/include/mp-units/random.h         |  8 +--
 test/unit_test/static/CMakeLists.txt          | 10 +++-
 test/unit_test/static/quantity_test.cpp       |  9 ++-
 9 files changed, 106 insertions(+), 24 deletions(-)
 create mode 100644 src/core/include/mp-units/quantity_spec_macro.h
 create mode 100644 src/mp-units.cpp

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index c0249ea936..fe1653a888 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -51,6 +51,20 @@ target_link_libraries(
 add_library(mp-units::mp-units ALIAS mp-units)
 install(TARGETS mp-units EXPORT mp-unitsTargets)
 
+# C++ module
+if(CMAKE_EXPERIMENTAL_CXX_MODULE_CMAKE_API)
+    add_library(mp-units-modules STATIC)
+    add_library(mp-units::modules ALIAS mp-units-modules)
+    target_sources(
+        mp-units-modules PUBLIC FILE_SET CXX_MODULES BASE_DIRS "${CMAKE_CURRENT_SOURCE_DIR}" FILES "mp-units.cpp"
+    )
+    target_link_libraries(mp-units-modules PRIVATE mp-units::mp-units)
+    target_include_directories(
+        mp-units-modules ${unitsAsSystem} INTERFACE $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/core/include>
+                                                    $<INSTALL_INTERFACE:include>
+    )
+endif()
+
 # local build
 export(EXPORT mp-unitsTargets NAMESPACE mp-units::)
 configure_file("mp-unitsConfig.cmake" "." COPYONLY)
diff --git a/src/core-fmt/include/mp-units/bits/fmt_hacks.h b/src/core-fmt/include/mp-units/bits/fmt_hacks.h
index 008c3159ef..340e014758 100644
--- a/src/core-fmt/include/mp-units/bits/fmt_hacks.h
+++ b/src/core-fmt/include/mp-units/bits/fmt_hacks.h
@@ -62,7 +62,7 @@ MP_UNITS_DIAGNOSTIC_POP
 
 #else
 
-#ifndef __cpp_lib_format
+#if !defined(__cpp_lib_format) && !defined(__cpp_lib_format_ranges)
 #error "std::formatting facility not supported"
 #endif
 
diff --git a/src/core/include/mp-units/bits/external/type_list.h b/src/core/include/mp-units/bits/external/type_list.h
index 5369ce18db..80b66e060f 100644
--- a/src/core/include/mp-units/bits/external/type_list.h
+++ b/src/core/include/mp-units/bits/external/type_list.h
@@ -24,6 +24,7 @@
 
 #include <mp-units/bits/external/hacks.h>  // IWYU pragma: keep
 #include <cstddef>
+#include <type_traits>
 #include <utility>
 
 MP_UNITS_DIAGNOSTIC_PUSH
diff --git a/src/core/include/mp-units/quantity_spec.h b/src/core/include/mp-units/quantity_spec.h
index 0bd2fe95e3..805182f971 100644
--- a/src/core/include/mp-units/quantity_spec.h
+++ b/src/core/include/mp-units/quantity_spec.h
@@ -32,6 +32,7 @@
 #include <mp-units/bits/reference_concepts.h>
 #include <mp-units/bits/representation_concepts.h>
 #include <mp-units/dimension.h>
+#include <mp-units/quantity_spec_macro.h>
 #include <tuple>
 
 namespace mp_units {
@@ -359,20 +360,6 @@ struct quantity_spec<Self, QS, Eq, Args...> : quantity_spec<Self, QS, Args...> {
   static constexpr quantity_character character = detail::quantity_character_init<Args...>(Eq.character);
 };
 
-#ifdef __cpp_explicit_this_parameter
-
-#define QUANTITY_SPEC(name, ...)                                          \
-  inline constexpr struct name : ::mp_units::quantity_spec<__VA_ARGS__> { \
-  } name
-
-#else
-
-#define QUANTITY_SPEC(name, ...)                                                \
-  inline constexpr struct name : ::mp_units::quantity_spec<name, __VA_ARGS__> { \
-  } name
-
-#endif
-
 
 /**
  * @brief A specification of a derived quantity
diff --git a/src/core/include/mp-units/quantity_spec_macro.h b/src/core/include/mp-units/quantity_spec_macro.h
new file mode 100644
index 0000000000..e95c8989a2
--- /dev/null
+++ b/src/core/include/mp-units/quantity_spec_macro.h
@@ -0,0 +1,13 @@
+#ifdef __cpp_explicit_this_parameter
+
+#define QUANTITY_SPEC(name, ...)                                          \
+  inline constexpr struct name : ::mp_units::quantity_spec<__VA_ARGS__> { \
+  } name
+
+#else
+
+#define QUANTITY_SPEC(name, ...)                                                \
+  inline constexpr struct name : ::mp_units::quantity_spec<name, __VA_ARGS__> { \
+  } name
+
+#endif
diff --git a/src/mp-units.cpp b/src/mp-units.cpp
new file mode 100644
index 0000000000..15a949475b
--- /dev/null
+++ b/src/mp-units.cpp
@@ -0,0 +1,58 @@
+module;
+
+// core
+#include <gsl/gsl-lite.hpp>
+#include <array>
+#include <compare>
+#include <concepts>
+#include <cstddef>
+#include <cstdint>
+#include <functional>
+#include <initializer_list>
+#include <iterator>
+#include <limits>
+#include <numbers>
+#include <numeric>
+#include <optional>
+#include <ranges>
+#include <string>
+#include <string_view>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+// core-io
+#include <sstream>
+
+// core-fmt
+#include <format>
+
+// utility
+#include <chrono>
+#include <cmath>
+#include <random>
+
+export module mp_units;
+
+export
+{
+// core
+#include <mp-units/core.h>
+
+// core-io
+#include <mp-units/ostream.h>
+
+// core-fmt
+#include <mp-units/format.h>
+
+// systems
+#include <mp-units/systems/angular/angular.h>
+#include <mp-units/systems/iec80000/iec80000.h>
+#include <mp-units/systems/isq/isq.h>
+#include <mp-units/systems/si/si.h>
+
+// utility
+#include <mp-units/chrono.h>
+#include <mp-units/math.h>
+#include <mp-units/random.h>
+}
diff --git a/src/utility/include/mp-units/random.h b/src/utility/include/mp-units/random.h
index 2c26b97a97..811494875d 100644
--- a/src/utility/include/mp-units/random.h
+++ b/src/utility/include/mp-units/random.h
@@ -30,7 +30,7 @@ namespace mp_units {
 
 namespace detail {
 template<Quantity Q, typename InputIt>
-static std::vector<typename Q::rep> i_qty_to_rep(InputIt first, InputIt last)
+std::vector<typename Q::rep> i_qty_to_rep(InputIt first, InputIt last)
 {
   std::vector<typename Q::rep> intervals_rep;
   intervals_rep.reserve(static_cast<size_t>(std::distance(first, last)));
@@ -41,7 +41,7 @@ static std::vector<typename Q::rep> i_qty_to_rep(InputIt first, InputIt last)
 }
 
 template<Quantity Q>
-static std::vector<typename Q::rep> bl_qty_to_rep(std::initializer_list<Q>& bl)
+std::vector<typename Q::rep> bl_qty_to_rep(std::initializer_list<Q>& bl)
 {
   std::vector<typename Q::rep> bl_rep;
   bl_rep.reserve(bl.size());
@@ -52,7 +52,7 @@ static std::vector<typename Q::rep> bl_qty_to_rep(std::initializer_list<Q>& bl)
 }
 
 template<Quantity Q, typename UnaryOperation>
-inline static std::vector<typename Q::rep> fw_bl_pwc(std::initializer_list<Q>& bl, UnaryOperation fw)
+std::vector<typename Q::rep> fw_bl_pwc(std::initializer_list<Q>& bl, UnaryOperation fw)
 {
   using rep = MP_UNITS_TYPENAME Q::rep;
   std::vector<rep> w_bl;
@@ -70,7 +70,7 @@ inline static std::vector<typename Q::rep> fw_bl_pwc(std::initializer_list<Q>& b
 }
 
 template<Quantity Q, typename UnaryOperation>
-static std::vector<typename Q::rep> fw_bl_pwl(std::initializer_list<Q>& bl, UnaryOperation fw)
+std::vector<typename Q::rep> fw_bl_pwl(std::initializer_list<Q>& bl, UnaryOperation fw)
 {
   std::vector<typename Q::rep> weights;
   weights.reserve(bl.size());
diff --git a/test/unit_test/static/CMakeLists.txt b/test/unit_test/static/CMakeLists.txt
index d8a6cb04ff..0fe085a8ed 100644
--- a/test/unit_test/static/CMakeLists.txt
+++ b/test/unit_test/static/CMakeLists.txt
@@ -23,7 +23,6 @@
 cmake_minimum_required(VERSION 3.2)
 
 add_library(unit_tests_static_truncating quantity_test.cpp)
-target_link_libraries(unit_tests_static_truncating PRIVATE mp-units::mp-units)
 target_compile_options(
     unit_tests_static_truncating PRIVATE $<IF:$<CXX_COMPILER_ID:MSVC>,/wd4242 /wd4244,-Wno-conversion>
 )
@@ -63,5 +62,10 @@ add_library(
     usc_test.cpp
 )
 
-target_link_libraries(unit_tests_static PRIVATE mp-units::mp-units)
-target_link_libraries(unit_tests_static PRIVATE unit_tests_static_truncating mp-units::mp-units)
+target_link_libraries(unit_tests_static PRIVATE unit_tests_static_truncating)
+foreach(target unit_tests_static_truncating unit_tests_static)
+    target_link_libraries(
+        "${target}" PRIVATE mp-units::mp-units $<$<TARGET_EXISTS:mp-units::modules>:mp-units::modules>
+    )
+    target_compile_definitions("${target}" PRIVATE $<$<TARGET_EXISTS:mp-units::modules>:MP_UNITS_MODULES>)
+endforeach()
diff --git a/test/unit_test/static/quantity_test.cpp b/test/unit_test/static/quantity_test.cpp
index c8fd713bd2..e12a59e166 100644
--- a/test/unit_test/static/quantity_test.cpp
+++ b/test/unit_test/static/quantity_test.cpp
@@ -21,12 +21,17 @@
 // SOFTWARE.
 
 #include "test_tools.h"
+#include <limits>
+#include <utility>
+#ifdef MP_UNITS_MODULES
+#include <mp-units/quantity_spec_macro.h>
+import mp_units;
+#else
 #include <mp-units/chrono.h>
 #include <mp-units/systems/isq/mechanics.h>
 #include <mp-units/systems/isq/space_and_time.h>
 #include <mp-units/systems/si/si.h>
-#include <limits>
-#include <utility>
+#endif
 
 template<>
 inline constexpr bool mp_units::is_vector<int> = true;