Add wx headers and ext

wxheaders/wx/meta/convertible.h

@@ -0,0 +1,60 @@
+/////////////////////////////////////////////////////////////////////////////
+// Name:        wx/meta/convertible.h
+// Purpose:     Test if types are convertible
+// Author:      Arne Steinarson
+// Created:     2008-01-10
+// Copyright:   (c) 2008 Arne Steinarson
+// Licence:     wxWindows licence
+/////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_META_CONVERTIBLE_H_
+#define _WX_META_CONVERTIBLE_H_
+
+//
+// Introduce an extra class to make this header compilable with g++3.2
+//
+template <class D, class B>
+struct wxConvertibleTo_SizeHelper
+{
+    static char Match(B* pb);
+    static int  Match(...);
+};
+
+// Helper to decide if an object of type D is convertible to type B (the test
+// succeeds in particular when D derives from B)
+template <class D, class B>
+struct wxConvertibleTo
+{
+    enum
+    {
+        value =
+            sizeof(wxConvertibleTo_SizeHelper<D,B>::Match(static_cast<D*>(NULL)))
+            ==
+            sizeof(char)
+    };
+};
+
+// This is similar to wxConvertibleTo, except that when using a C++11 compiler,
+// the case of D deriving from B non-publicly will be detected and the correct
+// value (false) will be deduced instead of getting a compile-time error as
+// with wxConvertibleTo. For pre-C++11 compilers there is no difference between
+// this helper and wxConvertibleTo.
+template <class D, class B>
+struct wxIsPubliclyDerived
+{
+    enum
+    {
+#if __cplusplus >= 201103 || (defined(_MSC_VER) && _MSC_VER >= 1600)
+        // If C++11 is available we use this, as on most compilers it's a
+        // built-in and will be evaluated at compile-time.
+        value = std::is_base_of<B, D>::value && std::is_convertible<D*, B*>::value
+#else
+        // When not using C++11, we fall back to wxConvertibleTo, which fails
+        // at compile-time if D doesn't publicly derive from B.
+        value = wxConvertibleTo<D, B>::value
+#endif
+    };
+};
+
+#endif // _WX_META_CONVERTIBLE_H_
+