Add boost::variant

boost/variant/detail/enable_recursive_fwd.hpp

@@ -0,0 +1,87 @@
+//-----------------------------------------------------------------------------
+// boost variant/detail/enable_recursive_fwd.hpp header file
+// See http://www.boost.org for updates, documentation, and revision history.
+//-----------------------------------------------------------------------------
+//
+// Copyright (c) 2003
+// Eric Friedman
+//
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_FWD_HPP
+#define BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_FWD_HPP
+
+#include "boost/mpl/aux_/config/ctps.hpp"
+
+#include "boost/mpl/bool_fwd.hpp"
+
+#   include "boost/mpl/bool.hpp"
+
+namespace boost {
+namespace detail { namespace variant {
+
+///////////////////////////////////////////////////////////////////////////////
+// (detail) tag recursive_flag
+//
+// Signifies that the variant should perform recursive substituion.
+//
+
+
+template <typename T>
+struct recursive_flag
+{
+    typedef T type;
+};
+
+
+///////////////////////////////////////////////////////////////////////////////
+// (detail) metafunction is_recursive_flag
+//
+// Signifies that the variant should perform recursive substituion.
+//
+
+
+template <typename T>
+struct is_recursive_flag
+    : mpl::false_
+{
+};
+
+template <typename T>
+struct is_recursive_flag< recursive_flag<T> >
+    : mpl::true_
+{
+};
+
+
+///////////////////////////////////////////////////////////////////////////////
+// (detail) metafunction enable_recursive
+//
+// Attempts recursive_variant_ tag substitution, wrapping with
+// boost::recursive_wrapper if substituion occurs w/ non-indirect result
+// (i.e., not a reference or pointer) *and* NoWrapper is false_.
+//
+template <
+      typename T
+    , typename RecursiveVariant
+    , typename NoWrapper = mpl::false_
+    >
+struct enable_recursive;
+
+///////////////////////////////////////////////////////////////////////////////
+// (detail) metafunction class quoted_enable_recursive
+//
+// Same behavior as enable_recursive metafunction (see above).
+//
+template <
+      typename RecursiveVariant
+    , typename NoWrapper = mpl::false_
+    >
+struct quoted_enable_recursive;
+
+}} // namespace detail::variant
+} // namespace boost
+
+#endif // BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_FWD_HPP