Added control of over the C++ standard used.

Author: robertosfield

CMakeLists.txt

@@ -90,6 +90,9 @@ if (VSG_SUPPORTS_Windowing)
     endif()
 endif()
 
+set(VSG_CXX_TARGET 17 CACHE STRING "Set target C++ standard version, valid values are 17, 20 & 23")
+
+
 option(VSG_USE_dynamic_cast "Use dynamic_cast in vsg::Object::cast<T>(), default is OFF and uses VSG native casting which provides 2-3x faster than using dynamic_cast<>." OFF)
 
 # this line needs to be after the call to setup_build_vars()

include/vsg/io/convert_utf.h

@@ -27,6 +27,37 @@ namespace vsg
 
     inline void convert_utf(const std::string& src, std::string& dst) { dst = src; }
     inline void convert_utf(const std::wstring& src, std::wstring& dst) { dst = src; }
+
+    #if defined(__cpp_char8_t)
+    inline void convert_utf(const std::u8string& src, std::u8string& dst) { dst = src; }
+    inline void convert_utf(const std::wstring& src, std::u8string& dst) { std::string temp_dst; convert_utf(src, temp_dst); dst.assign(temp_dst.begin(), temp_dst.end()); }
+    inline void convert_utf(const std::u8string& src, std::wstring& dst) { std::string temp_src(src.begin(), src.end()); convert_utf(temp_src, dst); }
+
+    inline void convert_utf(const char8_t c, std::u8string& dst)
+    {
+        dst.clear();
+        dst.push_back(c);
+    }
+    inline void convert_utf(const char8_t c, std::string& dst)
+    {
+        dst.clear();
+        dst.push_back(c);
+    }
+    inline void convert_utf(const char8_t c, std::wstring& dst)
+    {
+        dst.clear();
+        dst.push_back(static_cast<wchar_t>(c));
+    }
+
+    template<typename T>
+    T convert_utf(const std::u8string& src)
+    {
+        T dst;
+        convert_utf(src, dst);
+        return dst;
+    }
+    #endif
+
     inline void convert_utf(const char c, std::string& dst)
     {
         dst.clear();

src/vsg/CMakeLists.txt

@@ -411,7 +411,19 @@ ASSIGN_SOURCE_GROUPS("Header Files" "${VSG_SOURCE_DIR}/include/vsg" ${HEADERS})
 set_property(TARGET vsg PROPERTY VERSION ${VSG_VERSION_MAJOR}.${VSG_VERSION_MINOR}.${VSG_VERSION_PATCH})
 set_property(TARGET vsg PROPERTY SOVERSION ${VSG_SOVERSION})
 set_property(TARGET vsg PROPERTY POSITION_INDEPENDENT_CODE ON)
-target_compile_features(vsg PUBLIC cxx_std_17)
+
+if (VSG_CXX_TARGET EQUAL 23)
+    target_compile_features(vsg PUBLIC cxx_std_23)
+elseif (VSG_CXX_TARGET EQUAL 20)
+    target_compile_features(vsg PUBLIC cxx_std_20)
+elseif (VSG_CXX_TARGET EQUAL 17)
+    target_compile_features(vsg PUBLIC cxx_std_17)
+else()
+    message("Warning: invalid VSG_CXX_TARGET setting of " ${VSG_CXX_TARGET} " valid settings are 17, 20 or 23")
+    target_compile_features(vsg PUBLIC cxx_std_17)
+endif()
+
+
 if(WIN32)
     set_property(TARGET vsg PROPERTY RUNTIME_OUTPUT_NAME vsg-${VSG_SOVERSION})
 endif()