Add wx headers and ext

wxheaders/wx/meta/if.h

@@ -0,0 +1,56 @@
+/////////////////////////////////////////////////////////////////////////////
+// Name:        wx/meta/if.h
+// Purpose:     declares wxIf<> metaprogramming construct
+// Author:      Vaclav Slavik
+// Created:     2008-01-22
+// Copyright:   (c) 2008 Vaclav Slavik
+// Licence:     wxWindows licence
+/////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_META_IF_H_
+#define _WX_META_IF_H_
+
+#include "wx/defs.h"
+
+namespace wxPrivate
+{
+
+template <bool Cond>
+struct wxIfImpl;
+
+// specialization for true:
+template <>
+struct wxIfImpl<true>
+{
+    template<typename TTrue, typename TFalse> struct Result
+    {
+        typedef TTrue value;
+    };
+};
+
+// specialization for false:
+template<>
+struct wxIfImpl<false>
+{
+    template<typename TTrue, typename TFalse> struct Result
+    {
+        typedef TFalse value;
+    };
+};
+
+} // namespace wxPrivate
+
+// wxIf<> template defines nested type "value" which is the same as
+// TTrue if the condition Cond (boolean compile-time constant) was met and
+// TFalse if it wasn't.
+//
+// See wxVector<T> in vector.h for usage example
+template<bool Cond, typename TTrue, typename TFalse>
+struct wxIf
+{
+    typedef typename wxPrivate::wxIfImpl<Cond>
+                     ::template Result<TTrue, TFalse>::value
+            value;
+};
+
+#endif // _WX_META_IF_H_