forked from boostorg/mpl
124 lines
3.1 KiB
C++
124 lines
3.1 KiB
C++
//-----------------------------------------------------------------------------
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// boost mpl/aux_/single_element_iter.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) 2000-02
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// Aleksey Gurtovoy
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//
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// Permission to use, copy, modify, distribute and sell this software
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// and its documentation for any purpose is hereby granted without fee,
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// provided that the above copyright notice appears in all copies and
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// that both the copyright notice and this permission notice appear in
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// supporting documentation. No representations are made about the
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// suitability of this software for any purpose. It is provided "as is"
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// without express or implied warranty.
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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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#include "boost/mpl/iterator_tag.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_/config/nttp.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 ra_iter_tag_ category;
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typedef 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< 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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, 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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//BOOST_MPL_AUX_PASS_THROUGH_LAMBDA_SPEC(1, aux::single_element_iter)
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}} // namespace boost::mpl
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#endif // BOOST_MPL_AUX_SINGLE_ELEMENT_ITER_HPP_INCLUDED
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