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//-----------------------------------------------------------------------------
// 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"
#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
# include "boost/mpl/bool.hpp"
#else
# include "boost/type_traits/is_base_and_derived.hpp"
#endif
namespace boost {
namespace detail { namespace variant {
///////////////////////////////////////////////////////////////////////////////
// (detail) tag recursive_flag
//
// Signifies that the variant should perform recursive substituion.
//
#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
template <typename T>
struct recursive_flag
{
typedef T type;
};
#else // defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
struct recursive_flag_tag
{
};
template <typename T>
struct recursive_flag
: recursive_flag_tag
{
typedef T type;
};
#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION workaround
///////////////////////////////////////////////////////////////////////////////
// (detail) metafunction is_recursive_flag
//
// Signifies that the variant should perform recursive substituion.
//
#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
template <typename T>
struct is_recursive_flag
: mpl::false_
{
};
template <typename T>
struct is_recursive_flag< recursive_flag<T> >
: mpl::true_
{
};
#else // defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
template <typename T>
struct is_recursive_flag
: is_base_and_derived< recursive_flag_tag,T >
{
};
#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION workaround
///////////////////////////////////////////////////////////////////////////////
// (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
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