williamr@2: //-----------------------------------------------------------------------------
williamr@2: // boost variant/detail/over_sequence.hpp header file
williamr@2: // See http://www.boost.org for updates, documentation, and revision history.
williamr@2: //-----------------------------------------------------------------------------
williamr@2: //
williamr@2: // Copyright (c) 2003
williamr@2: // Eric Friedman
williamr@2: //
williamr@2: // Portions Copyright (C) 2002 David Abrahams
williamr@2: //
williamr@2: // Distributed under the Boost Software License, Version 1.0. (See
williamr@2: // accompanying file LICENSE_1_0.txt or copy at
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: 
williamr@2: #ifndef BOOST_VARIANT_DETAIL_OVER_SEQUENCE_HPP
williamr@2: #define BOOST_VARIANT_DETAIL_OVER_SEQUENCE_HPP
williamr@2: 
williamr@2: #include "boost/mpl/aux_/config/ctps.hpp"
williamr@2: #if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
williamr@2: #   include "boost/mpl/eval_if.hpp"
williamr@2: #   include "boost/mpl/bool.hpp"
williamr@2: #   include "boost/mpl/identity.hpp"
williamr@2: #   include "boost/type.hpp"
williamr@2: #endif
williamr@2: 
williamr@2: 
williamr@2: namespace boost {
williamr@2: namespace detail { namespace variant {
williamr@2: 
williamr@2: ///////////////////////////////////////////////////////////////////////////////
williamr@2: // (detail) class over_sequence
williamr@2: //
williamr@2: // Wrapper used to indicate bounded types for variant are from type sequence.
williamr@2: //
williamr@2: template <typename Types>
williamr@2: struct over_sequence
williamr@2: {
williamr@2:     typedef Types type;
williamr@2: };
williamr@2: 
williamr@2: ///////////////////////////////////////////////////////////////////////////////
williamr@2: // (detail) metafunction is_over_sequence (modeled on code by David Abrahams)
williamr@2: //
williamr@2: // Indicates whether the specified type is of form over_sequence<...> or not.
williamr@2: //
williamr@2: 
williamr@2: #if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
williamr@2: 
williamr@2: template <typename T>
williamr@2: struct is_over_sequence
williamr@2:     : mpl::false_
williamr@2: {
williamr@2: };
williamr@2: 
williamr@2: template <typename Types>
williamr@2: struct is_over_sequence< over_sequence<Types> >
williamr@2:     : mpl::true_
williamr@2: {
williamr@2: };
williamr@2: 
williamr@2: #else // defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
williamr@2: 
williamr@2: typedef char (&yes_over_sequence_t)[1];
williamr@2: typedef char (&no_over_sequence_t)[2];
williamr@2: 
williamr@2: no_over_sequence_t is_over_sequence_test(...);
williamr@2: 
williamr@2: template<typename T>
williamr@2: yes_over_sequence_t is_over_sequence_test(
williamr@2:       type< ::boost::detail::variant::over_sequence<T> >
williamr@2:     );
williamr@2: 
williamr@2: template<typename T>
williamr@2: struct is_over_sequence_impl
williamr@2: {
williamr@2:     BOOST_STATIC_CONSTANT(bool, value = (
williamr@2:           sizeof(is_over_sequence_test(type<T>()))
williamr@2:           == sizeof(yes_over_sequence_t)
williamr@2:         ));
williamr@2: };
williamr@2: 
williamr@2: template <typename T>
williamr@2: struct is_over_sequence
williamr@2:     : mpl::bool_<
williamr@2:           ::boost::detail::variant::is_over_sequence_impl<T>::value
williamr@2:         >
williamr@2: {
williamr@2: };
williamr@2: 
williamr@2: #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION workaround
williamr@2: 
williamr@2: }} // namespace detail::variant
williamr@2: } // namespace boost
williamr@2: 
williamr@2: #endif // BOOST_VARIANT_DETAIL_OVER_SEQUENCE_HPP