//----------------------------------------------------------------------------- | |
// 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 |