119 lines
2.6 KiB
C++
119 lines
2.6 KiB
C++
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#ifndef BOOST_MPL_AUX_SINGLE_ELEMENT_ITER_HPP_INCLUDED
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#define BOOST_MPL_AUX_SINGLE_ELEMENT_ITER_HPP_INCLUDED
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// Copyright Aleksey Gurtovoy 2000-2004
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//
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// Distributed under the Boost Software License, Version 1.0.
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// (See 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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//
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// See http://www.boost.org/libs/mpl for documentation.
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// $Source$
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// $Date$
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// $Revision$
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#include <boost/mpl/iterator_tags.hpp>
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#include <boost/mpl/plus.hpp>
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#include <boost/mpl/minus.hpp>
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#include <boost/mpl/int.hpp>
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#include <boost/mpl/aux_/value_wknd.hpp>
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#include <boost/mpl/aux_/iterator_names.hpp>
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#include <boost/mpl/aux_/lambda_spec.hpp>
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#include <boost/mpl/aux_/config/ctps.hpp>
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#include <boost/mpl/aux_/nttp_decl.hpp>
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namespace boost { namespace mpl {
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namespace aux {
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template< typename T, int N >
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struct single_element_iter;
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// random access support
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template< typename T, BOOST_MPL_AUX_NTTP_DECL(int, N) >
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struct single_iter_base
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{
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typedef random_access_iterator_tag category;
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typedef mpl::int_<N> position;
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template< typename D >
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struct BOOST_MPL_AUX_ITERATOR_ADVANCE
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{
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typedef plus< mpl::int_<N>,D > n_;
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typedef single_element_iter<
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T
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, BOOST_MPL_AUX_VALUE_WKND(n_)::value
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> type;
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};
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template< typename U >
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struct BOOST_MPL_AUX_ITERATOR_DISTANCE
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{
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typedef typename minus<
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typename U::position
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, mpl::int_<N>
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>::type type;
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};
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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 single_element_iter<T,0>
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: single_iter_base<T,0>
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{
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typedef single_element_iter<T,1> next;
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typedef T type;
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};
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template< typename T >
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struct single_element_iter<T,1>
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: single_iter_base<T,1>
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{
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typedef single_element_iter<T,0> prior;
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};
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#else
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template< BOOST_MPL_AUX_NTTP_DECL(int, N) > struct single_iter_impl
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{
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template< typename T > struct result_;
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};
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template<>
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struct single_iter_impl<0>
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{
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template< typename T > struct result_
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: single_iter_base<T,0>
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{
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typedef single_element_iter<T,1> next;
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typedef T type;
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};
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};
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template<>
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struct single_iter_impl<1>
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{
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template< typename T > struct result_
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: single_iter_base<T,1>
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{
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typedef single_element_iter<T,0> prior;
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};
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};
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template< typename T, BOOST_MPL_AUX_NTTP_DECL(int, N) >
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struct single_element_iter
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: single_iter_impl<N>::template result_<T>
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{
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};
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#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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} // namespace aux
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}}
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#endif // BOOST_MPL_AUX_SINGLE_ELEMENT_ITER_HPP_INCLUDED
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