Add support for C++ modules

CMakeLists.txt

@@ -26,6 +26,28 @@ endif()
 
 
 
+option(TSL_ORDERED_MAP_BUILD_MODULE "Build the C++20 module for tsl::ordered_map" OFF)
+
+if(TSL_ORDERED_MAP_BUILD_MODULE)
+    if(CMAKE_CXX_STANDARD LESS 20)
+        message(FATAL_ERROR "TSL_ORDERED_MAP_BUILD_MODULE requires C++20 or later (CMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD})")
+    endif()
+
+    add_library(ordered_map_module)
+    add_library(tsl::ordered_map_module ALIAS ordered_map_module)
+
+    target_sources(ordered_map_module
+                   PUBLIC FILE_SET CXX_MODULES FILES
+                   "${CMAKE_CURRENT_SOURCE_DIR}/src/tsl.ordered_map.cppm")
+
+    target_link_libraries(ordered_map_module PUBLIC tsl::ordered_map)
+    set_target_properties(ordered_map_module PROPERTIES CXX_STANDARD 20)
+
+    install(TARGETS ordered_map_module
+            EXPORT tsl-ordered-mapTargets
+            FILE_SET CXX_MODULES DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")
+endif()
+
 include(CMakePackageConfigHelpers)
 
 ## Install include directory and potential natvis file

README.md

@@ -25,6 +25,7 @@ Two classes are provided: `tsl::ordered_map` and `tsl::ordered_set`.
 - Support for efficient serialization and deserialization (see [example](#serialization) and the `serialize/deserialize` methods in the [API](https://tessil.github.io/ordered-map/classtsl_1_1ordered__map.html) for details).
 - The library can be used with exceptions disabled (through `-fno-exceptions` option on Clang and GCC, without an `/EH` option on MSVC or simply by defining `TSL_NO_EXCEPTIONS`). `std::terminate` is used in replacement of the `throw` instruction when exceptions are disabled.
 - API closely similar to `std::unordered_map` and `std::unordered_set`.
+- Support for C++ modules (requires C++20 or later)
 
 ### Differences compared to `std::unordered_map`
 `tsl::ordered_map` tries to have an interface similar to `std::unordered_map`, but some differences exist.
@@ -82,6 +83,8 @@ cmake --build .
 ./tsl_ordered_map_tests 
 ```
 
+To enable C++ modules, the version must be at least C++20 on any compiler supporting C++ modules (minimal versions usually Clang 18, GCC 15, and MSVC 17). When configuring CMake, pass `-DTSL_ORDERED_MAP_BUILD_MODULE=ON` to enable the `TSL_ORDERED_MAP_BUILD_MODULE` option. This creates a module `tsl.ordered_map`, which exports `tsl::ordered_map` and `tsl::ordered_set`.
+
 ### Usage
 
 The API can be found [here](https://tessil.github.io/ordered-map/).

include/tsl/ordered_hash.h

@@ -117,7 +117,7 @@ const T& clamp(const T& v, const T& lo, const T& hi) {
 }
 
 template <typename T, typename U>
-static T numeric_cast(U value,
+T numeric_cast(U value,
                       const char* error_message = "numeric_cast() failed.") {
   T ret = static_cast<T>(value);
   if (static_cast<U>(ret) != value) {
@@ -145,7 +145,7 @@ static_assert(std::numeric_limits<slz_size_type>::max() >=
               "slz_size_type must be >= std::size_t");
 
 template <class T, class Deserializer>
-static T deserialize_value(Deserializer& deserializer) {
+T deserialize_value(Deserializer& deserializer) {
   // MSVC < 2017 is not conformant, circumvent the problem by removing the
   // template keyword
 #if defined(_MSC_VER) && _MSC_VER < 1910

src/tsl.ordered_map.cppm

@@ -0,0 +1,34 @@
+/**
+ * MIT License
+ *
+ * Copyright (c) 2017 Thibaut Goetghebuer-Planchon <tessil@gmx.com>
+ *
+ * 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.
+ */
+module;
+
+#include "tsl/ordered_map.h"
+#include "tsl/ordered_set.h"
+
+export module tsl.ordered_map;
+
+export namespace tsl {
+    using tsl::ordered_map;
+    using tsl::ordered_set;
+}