Chris@16: 
Chris@16: #ifndef BOOST_MPL_AUX_SINGLE_ELEMENT_ITER_HPP_INCLUDED
Chris@16: #define BOOST_MPL_AUX_SINGLE_ELEMENT_ITER_HPP_INCLUDED
Chris@16: 
Chris@16: // Copyright Aleksey Gurtovoy 2000-2004
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. 
Chris@16: // (See accompanying file LICENSE_1_0.txt or copy at 
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: // See http://www.boost.org/libs/mpl for documentation.
Chris@16: 
Chris@101: // $Id$
Chris@101: // $Date$
Chris@101: // $Revision$
Chris@16: 
Chris@16: #include <boost/mpl/iterator_tags.hpp>
Chris@16: #include <boost/mpl/advance_fwd.hpp>
Chris@16: #include <boost/mpl/distance_fwd.hpp>
Chris@16: #include <boost/mpl/next_prior.hpp>
Chris@16: #include <boost/mpl/deref.hpp>
Chris@16: #include <boost/mpl/int.hpp>
Chris@16: #include <boost/mpl/aux_/nttp_decl.hpp>
Chris@16: #include <boost/mpl/aux_/value_wknd.hpp>
Chris@16: #include <boost/mpl/aux_/config/ctps.hpp>
Chris@16: 
Chris@16: namespace boost { namespace mpl { 
Chris@16: 
Chris@16: #if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
Chris@16: 
Chris@16: namespace aux {
Chris@16: 
Chris@16: template< typename T, BOOST_MPL_AUX_NTTP_DECL(int, is_last_) >
Chris@16: struct sel_iter;
Chris@16: 
Chris@16: template< typename T >
Chris@16: struct sel_iter<T,0>
Chris@16: {
Chris@16:     typedef random_access_iterator_tag category;
Chris@16:     typedef sel_iter<T,1> next;
Chris@16:     typedef T type;
Chris@16: };
Chris@16: 
Chris@16: template< typename T >
Chris@16: struct sel_iter<T,1>
Chris@16: {
Chris@16:     typedef random_access_iterator_tag category;
Chris@16:     typedef sel_iter<T,0> prior;
Chris@16: };
Chris@16: 
Chris@16: } // namespace aux
Chris@16: 
Chris@16: template< typename T, BOOST_MPL_AUX_NTTP_DECL(int, is_last_), typename Distance >
Chris@16: struct advance< aux::sel_iter<T,is_last_>,Distance>
Chris@16: {
Chris@16:     typedef aux::sel_iter<
Chris@16:           T
Chris@16:         , ( is_last_ + BOOST_MPL_AUX_NESTED_VALUE_WKND(int, Distance) )
Chris@16:         > type;
Chris@16: };
Chris@16: 
Chris@16: template< 
Chris@16:       typename T
Chris@16:     , BOOST_MPL_AUX_NTTP_DECL(int, l1)
Chris@16:     , BOOST_MPL_AUX_NTTP_DECL(int, l2) 
Chris@16:     >
Chris@16: struct distance< aux::sel_iter<T,l1>, aux::sel_iter<T,l2> >
Chris@16:     : int_<( l2 - l1 )>
Chris@16: {
Chris@16: };
Chris@16: 
Chris@16: #else
Chris@16: 
Chris@16: namespace aux {
Chris@16: 
Chris@16: struct sel_iter_tag;
Chris@16: 
Chris@16: template< typename T, BOOST_MPL_AUX_NTTP_DECL(int, is_last_) >
Chris@16: struct sel_iter
Chris@16: {
Chris@16:     enum { pos_ = is_last_ };
Chris@16:     typedef aux::sel_iter_tag tag;
Chris@16:     typedef random_access_iterator_tag category;
Chris@16: 
Chris@16:     typedef sel_iter<T,(is_last_ + 1)> next;
Chris@16:     typedef sel_iter<T,(is_last_ - 1)> prior;
Chris@16:     typedef T type;
Chris@16: };
Chris@16: 
Chris@16: } // namespace aux
Chris@16: 
Chris@16: template<> struct advance_impl<aux::sel_iter_tag>
Chris@16: {
Chris@16:     template< typename Iterator, typename N > struct apply
Chris@16:     {
Chris@16:         enum { pos_ = Iterator::pos_, n_ = N::value };
Chris@16:         typedef aux::sel_iter<
Chris@16:               typename Iterator::type
Chris@16:             , (pos_ + n_)
Chris@16:             > type;
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template<> struct distance_impl<aux::sel_iter_tag>
Chris@16: {
Chris@16:     template< typename Iter1, typename Iter2 > struct apply
Chris@16:     {
Chris@16:         enum { pos1_ = Iter1::pos_, pos2_ = Iter2::pos_ };
Chris@16:         typedef int_<( pos2_ - pos1_ )> type;
Chris@16:         BOOST_STATIC_CONSTANT(int, value = ( pos2_ - pos1_ ));
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
Chris@16: 
Chris@16: }}
Chris@16: 
Chris@16: #endif // BOOST_MPL_AUX_SINGLE_ELEMENT_ITER_HPP_INCLUDED