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