Added OffsetOf header and function

Designed to replace the old offsetof macro


Former-commit-id: faa45ebfd3c1f9cc817f6fccf5c94d2c1527349d

include/Nazara/Core/OffsetOf.hpp

@@ -0,0 +1,24 @@
+// Copyright (C) 2014 Jérôme Leclercq
+// This file is part of the "Nazara Engine - Core module"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#pragma once
+
+#ifndef NAZARA_OFFSETOF_HPP
+#define NAZARA_OFFSETOF_HPP
+
+// Par "Jesse Good" de SO:
+// http://stackoverflow.com/questions/12811330/c-compile-time-offsetof-inside-a-template?answertab=votes#tab-top
+
+template <typename T, typename M> T NzImplGetClassType(M T::*);
+template <typename T, typename M> M NzImplGetMemberType(M T::*);
+
+template <typename T, typename R, R T::*M>
+constexpr std::size_t NzImplOffsetOf()
+{
+	return reinterpret_cast<std::size_t>(&(((T*)0)->*M));
+}
+
+#define NzOffsetOf(type, member) NzImplOffsetOf<decltype(NzImplGetClassType(&type::member)), decltype(NzImplGetMemberType(&type::member)), &type::member>()
+
+#endif // NAZARA_OFFSETOF_HPP