add support for C++20 module (and C++23 std module)

Author: Arthapz

src/pugixml.cpp

@@ -16,6 +16,7 @@
 
 #include "pugixml.hpp"
 
+#ifndef PUGIXML_EXPORT_MODULE
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
@@ -44,6 +45,7 @@
 #if defined(__linux__) || defined(__APPLE__)
 #include <sys/stat.h>
 #endif
+#endif
 
 #ifdef _MSC_VER
 #	pragma warning(push)
@@ -196,8 +198,10 @@ namespace pugi
 	typedef unsigned __int32 uint32_t;
 }
 #else
+#ifndef PUGIXML_EXPORT_MODULE
 #	include <stdint.h>
 #endif
+#endif
 
 // Memory allocation
 PUGI_IMPL_NS_BEGIN

src/pugixml.cppm

@@ -0,0 +1,71 @@
+/**
+ * pugixml parser - version 1.14
+ * --------------------------------------------------------
+ * Copyright (C) 2006-2024, by Arseny Kapoulkine (arseny.kapoulkine@gmail.com)
+ * Report bugs and download new versions at https://pugixml.org/
+ *
+ * This library is distributed under the MIT License. See notice at the end
+ * of this file.
+ *
+ * This work is based on the pugxml parser, which is:
+ * Copyright (C) 2003, by Kristen Wegner (kristen@tima.net)
+ */
+
+module;
+
+#define PUGIXML_EXPORT_MODULE
+
+#include <pugiconfig.hpp>
+
+#ifndef PUGIXML_USE_STD_MODULE
+#	include <string_view>
+#	include <iterator>
+#	include <istream>
+#	include <ostream>
+#	include <string>
+#	include <new>
+#	include <exception>
+#endif
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+#include <limits.h>
+#include <stdint.h>
+
+#ifdef PUGIXML_WCHAR_MODE
+#	include <wchar.h>
+#endif
+
+#ifndef PUGIXML_NO_XPATH
+#	include <math.h>
+#	include <float.h>
+#endif
+
+#if defined(__linux__) || defined(__APPLE__)
+#	include <sys/stat.h>
+#endif
+
+export module pugixml;
+
+#ifdef PUGIXML_USE_STD_MODULE
+import std.compat;
+#endif
+
+#define PUGIXML_MODULE_EXPORT export
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Winclude-angled-in-module-purview"
+#endif
+#include <pugixml.hpp>
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
+
+
+module :private;
+
+#define PUGIXML_SOURCE "pugixml.cpp"
+#include PUGIXML_SOURCE

src/pugixml.hpp

@@ -23,6 +23,7 @@
 #ifndef HEADER_PUGIXML_HPP
 #define HEADER_PUGIXML_HPP
 
+#ifndef PUGIXML_EXPORT_MODULE
 // Include stddef.h for size_t and ptrdiff_t
 #include <stddef.h>
 
@@ -37,6 +38,7 @@
 #	include <iosfwd>
 #	include <string>
 #endif
+#endif
 
 // Check if std::string_view is both requested and available
 #if defined(PUGIXML_STRING_VIEW) && !defined(PUGIXML_NO_STL)
@@ -48,8 +50,10 @@
 #endif
 
 // Include string_view if appropriate
-#ifdef PUGIXML_HAS_STRING_VIEW
-#	include <string_view>
+#ifndef PUGIXML_MODULE_EXPORT
+#	ifdef PUGIXML_HAS_STRING_VIEW
+#		include <string_view>
+#	endif
 #endif
 
 // Macro for deprecated features
@@ -150,11 +154,11 @@
 // If C++ is 2017 or higher, add 'inline' qualifiers for constants
 // required for C++20 module
 #ifndef PUGIXML_CONSTANT
-# if __cplusplus >= 201703
-#   define PUGIXML_CONSTANT inline PUGIXML_CONSTEXPR
-# else
-#   define PUGIXML_CONSTANT PUGIXML_CONSTEXPR
-# endif
+#	if __cplusplus >= 201703
+#		define PUGIXML_CONSTANT inline PUGIXML_CONSTEXPR
+#	else
+#		define PUGIXML_CONSTANT PUGIXML_CONSTEXPR
+#	endif
 #endif
 
 // Character interface macros
@@ -166,6 +170,10 @@
 #	define PUGIXML_CHAR char
 #endif
 
+#ifndef PUGIXML_MODULE_EXPORT
+#	define PUGIXML_MODULE_EXPORT
+#endif
+
 namespace pugi
 {
 	// Character type used for all internal storage and operations; depends on PUGIXML_WCHAR_MODE
@@ -183,7 +191,7 @@ namespace pugi
 }
 
 // The PugiXML namespace
-namespace pugi
+PUGIXML_MODULE_EXPORT namespace pugi
 {
 	// Tree node types
 	enum xml_node_type