Add support for C++20 modules

CMakeLists.txt

@@ -4,6 +4,12 @@ project(tinyxml2 VERSION 11.0.0)
 include(CTest)
 option(tinyxml2_BUILD_TESTING "Build tests for tinyxml2" "${BUILD_TESTING}")
 
+if (CMAKE_VERSION VERSION_GREATER_EQUAL 3.28)
+    option(tinyxml2_BUILD_MODULE "Build C++ module for tinyxml2" OFF)
+else ()
+    set(tinyxml2_BUILD_MODULE OFF)
+endif ()
+
 ##
 ## Honor tinyxml2_SHARED_LIBS to match install interface
 ##
@@ -55,6 +61,30 @@ if (tinyxml2_BUILD_TESTING)
     set_tests_properties(xmltest PROPERTIES PASS_REGULAR_EXPRESSION ", Fail 0")
 endif ()
 
+##
+## C++ Module build
+##
+
+if (tinyxml2_BUILD_MODULE AND CMAKE_VERSION VERSION_GREATER_EQUAL 3.28)
+
+    add_library(tinyxml2_module)
+    target_sources(tinyxml2_module
+        PUBLIC
+            FILE_SET CXX_MODULES FILES
+            tinyxml2.cppm
+    )
+    target_link_libraries(tinyxml2_module PUBLIC tinyxml2::tinyxml2)
+    target_compile_features(tinyxml2_module PUBLIC cxx_std_20)
+    add_library(tinyxml2::tinyxml2_module ALIAS tinyxml2_module)
+
+    set_target_properties(
+        tinyxml2_module
+        PROPERTIES
+        VERSION "${tinyxml2_VERSION}"
+        SOVERSION "${tinyxml2_VERSION_MAJOR}"
+    )
+endif ()
+
 ##
 ## Installation
 ##
@@ -83,6 +113,17 @@ install(
     INCLUDES DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
 )
 
+if (tinyxml2_BUILD_MODULE)
+    install(
+        TARGETS tinyxml2_module EXPORT tinyxml2-targets
+        RUNTIME COMPONENT tinyxml2_runtime
+        LIBRARY COMPONENT tinyxml2_runtime
+        NAMELINK_COMPONENT tinyxml2_development
+        ARCHIVE COMPONENT tinyxml2_development
+        FILE_SET CXX_MODULES DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
+    )
+endif ()
+
 # Type-specific targets
 
 if (BUILD_SHARED_LIBS)

readme.md

@@ -282,6 +282,9 @@ There are 2 files in TinyXML-2:
 And additionally a test file:
 * `xmltest.cpp`
 
+And additionally a module:
+* `tinyxml2.cppm`
+
 Generally speaking, the intent is that you simply include the `tinyxml2.cpp` and 
 `tinyxml2.h` files in your project and build with your other source code.
 
@@ -290,6 +293,9 @@ There is also a CMake build included. CMake is the general build for TinyXML-2.
 (Additional build systems are costly to maintain, and tend to become outdated. They are
 being removed over time.)
 
+If using C++20 or later and CMake 3.28+, the option `tinyxml2_BUILD_MODULE` may be enabled,
+which enables building the `tinyxml2` module.
+
 ### Building TinyXML-2 - Using vcpkg
 
 You can download and install TinyXML-2 using the [vcpkg](https://github.com/Microsoft/vcpkg) dependency manager:

tinyxml2.cppm

@@ -0,0 +1,53 @@
+/*
+Original code by Lee Thomason (www.grinninglizard.com)
+
+This software is provided 'as-is', without any express or implied
+warranty. In no event will the authors be held liable for any
+damages arising from the use of this software.
+
+Permission is granted to anyone to use this software for any
+purpose, including commercial applications, and to alter it and
+redistribute it freely, subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must
+not claim that you wrote the original software. If you use this
+software in a product, an acknowledgment in the product documentation
+would be appreciated but is not required.
+
+2. Altered source versions must be plainly marked as such, and
+must not be misrepresented as being the original software.
+
+3. This notice may not be removed or altered from any source
+distribution.
+*/
+
+module;
+
+#include "tinyxml2.h"
+
+export module tinyxml2;
+
+export namespace tinyxml2 {
+    inline constexpr int MAX_ELEMENT_DEPTH = TINYXML2_MAX_ELEMENT_DEPTH;
+
+    using tinyxml2::XMLAttribute;
+    using tinyxml2::XMLComment;
+    using tinyxml2::XMLConstHandle;
+    using tinyxml2::XMLDeclaration;
+    using tinyxml2::XMLDocument;
+    using tinyxml2::XMLElement;
+    using tinyxml2::XMLError;
+    using tinyxml2::XMLHandle;
+    using tinyxml2::XMLNode;
+    using tinyxml2::XMLPrinter;
+    using tinyxml2::XMLText;
+    using tinyxml2::XMLUnknown;
+    using tinyxml2::XMLUtil;
+    using tinyxml2::XMLVisitor;
+
+    using tinyxml2::DynArray;
+    using tinyxml2::MemPool;
+    using tinyxml2::MemPoolT;
+    using tinyxml2::StrPair;
+    using tinyxml2::Whitespace;
+} // namespace tinyxml2