bring C++14 type traits aliases for C++11 support

include/mapnik/cxx11_support.hpp

@@ -0,0 +1,43 @@
+/*****************************************************************************
+ *
+ * This file is part of Mapnik (c++ mapping toolkit)
+ *
+ * Copyright (C) 2016 Artem Pavlenko
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ *****************************************************************************/
+
+#ifndef MAPNIK_CXX11_SUPPORT_HPP
+#define MAPNIK_CXX11_SUPPORT_HPP
+
+#include <type_traits>
+
+namespace mapnik {
+namespace detail {
+
+template <bool B, typename T, typename F>
+using conditional_t = typename std::conditional<B, T, F>::type;
+
+template <typename T>
+using decay_t = typename std::decay<T>::type;
+
+template <bool B, typename T = void>
+using enable_if_t = typename std::enable_if<B, T>::type;
+
+} // namespace detail
+} // namespace mapnik
+
+#endif // MAPNIK_CXX11_SUPPORT_HPP