//----------------------------------------------------------------------------- | |
// boost variant/static_visitor.hpp header file | |
// See http://www.boost.org for updates, documentation, and revision history. | |
//----------------------------------------------------------------------------- | |
// | |
// Copyright (c) 2002-2003 | |
// 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_STATIC_VISITOR_HPP | |
#define BOOST_VARIANT_STATIC_VISITOR_HPP | |
#include "boost/config.hpp" | |
#include "boost/detail/workaround.hpp" | |
#include "boost/mpl/if.hpp" | |
#include "boost/type_traits/is_base_and_derived.hpp" | |
#if BOOST_WORKAROUND(BOOST_MSVC, < 1300) | |
# include "boost/type_traits/is_same.hpp" | |
#endif | |
// should be the last #include | |
#include "boost/type_traits/detail/bool_trait_def.hpp" | |
namespace boost { | |
////////////////////////////////////////////////////////////////////////// | |
// class template static_visitor | |
// | |
// An empty base class that typedefs the return type of a deriving static | |
// visitor. The class is analogous to std::unary_function in this role. | |
// | |
namespace detail { | |
struct is_static_visitor_tag { }; | |
typedef void static_visitor_default_return; | |
} // namespace detail | |
template <typename R = ::boost::detail::static_visitor_default_return> | |
class static_visitor | |
: public detail::is_static_visitor_tag | |
{ | |
public: // typedefs | |
typedef R result_type; | |
protected: // for use as base class only | |
static_visitor() { } | |
~static_visitor() { } | |
}; | |
////////////////////////////////////////////////////////////////////////// | |
// metafunction is_static_visitor | |
// | |
// Value metafunction indicates whether the specified type derives from | |
// static_visitor<...>. | |
// | |
// NOTE #1: This metafunction does NOT check whether the specified type | |
// fulfills the requirements of the StaticVisitor concept. | |
// | |
// NOTE #2: This template never needs to be specialized! | |
// | |
namespace detail { | |
template <typename T> | |
struct is_static_visitor_impl | |
{ | |
BOOST_STATIC_CONSTANT(bool, value = | |
(::boost::is_base_and_derived< | |
detail::is_static_visitor_tag, | |
T | |
>::value)); | |
}; | |
} // namespace detail | |
BOOST_TT_AUX_BOOL_TRAIT_DEF1( | |
is_static_visitor | |
, T | |
, (::boost::detail::is_static_visitor_impl<T>::value) | |
) | |
} // namespace boost | |
#include "boost/type_traits/detail/bool_trait_undef.hpp" | |
#endif // BOOST_VARIANT_STATIC_VISITOR_HPP |