Chris@16: 
Chris@16: #ifndef BOOST_MPL_AUX_BEGIN_END_IMPL_HPP_INCLUDED
Chris@16: #define BOOST_MPL_AUX_BEGIN_END_IMPL_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/begin_end_fwd.hpp>
Chris@16: #include <boost/mpl/sequence_tag_fwd.hpp>
Chris@16: #include <boost/mpl/void.hpp>
Chris@16: #include <boost/mpl/eval_if.hpp>
Chris@16: #include <boost/mpl/aux_/has_begin.hpp>
Chris@16: #include <boost/mpl/aux_/na.hpp>
Chris@16: #include <boost/mpl/aux_/traits_lambda_spec.hpp>
Chris@16: #include <boost/mpl/aux_/config/eti.hpp>
Chris@16: 
Chris@16: namespace boost { namespace mpl {
Chris@16: 
Chris@16: 
Chris@16: namespace aux { 
Chris@16: 
Chris@16: template< typename Sequence > 
Chris@16: struct begin_type 
Chris@16: { 
Chris@16:     typedef typename Sequence::begin type; 
Chris@16: };
Chris@16: template< typename Sequence > 
Chris@16: struct end_type
Chris@16: { 
Chris@16:     typedef typename Sequence::end type; 
Chris@16: };
Chris@16: 
Chris@16: }
Chris@16: 
Chris@16: // default implementation; conrete sequences might override it by 
Chris@16: // specializing either the 'begin_impl/end_impl' or the primary 
Chris@16: // 'begin/end' templates
Chris@16: 
Chris@16: template< typename Tag >
Chris@16: struct begin_impl
Chris@16: {
Chris@16:     template< typename Sequence > struct apply
Chris@16:     {
Chris@16:         typedef typename eval_if<aux::has_begin<Sequence, true_>,
Chris@16:                                  aux::begin_type<Sequence>, void_>::type type;
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: template< typename Tag >
Chris@16: struct end_impl
Chris@16: {
Chris@16:     template< typename Sequence > struct apply
Chris@16:     {
Chris@16:         typedef typename eval_if<aux::has_begin<Sequence, true_>,
Chris@16:                                  aux::end_type<Sequence>, void_>::type type;
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: // specialize 'begin_trait/end_trait' for two pre-defined tags
Chris@16: 
Chris@16: #   define AUX778076_IMPL_SPEC(name, tag, result) \
Chris@16: template<> \
Chris@16: struct name##_impl<tag> \
Chris@16: { \
Chris@16:     template< typename Sequence > struct apply \
Chris@16:     { \
Chris@16:         typedef result type; \
Chris@16:     }; \
Chris@16: }; \
Chris@16: /**/
Chris@16: 
Chris@16: // a sequence with nested 'begin/end' typedefs; just query them
Chris@16: AUX778076_IMPL_SPEC(begin, nested_begin_end_tag, typename Sequence::begin)
Chris@16: AUX778076_IMPL_SPEC(end, nested_begin_end_tag, typename Sequence::end)
Chris@16: 
Chris@16: // if a type 'T' does not contain 'begin/end' or 'tag' members 
Chris@16: // and doesn't specialize either 'begin/end' or 'begin_impl/end_impl' 
Chris@16: // templates, then we end up here
Chris@16: AUX778076_IMPL_SPEC(begin, non_sequence_tag, void_)
Chris@16: AUX778076_IMPL_SPEC(end, non_sequence_tag, void_)
Chris@16: AUX778076_IMPL_SPEC(begin, na, void_)
Chris@16: AUX778076_IMPL_SPEC(end, na, void_)
Chris@16: 
Chris@16: #   undef AUX778076_IMPL_SPEC
Chris@16: 
Chris@16: 
Chris@16: BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC_IMPL(1,begin_impl)
Chris@16: BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC_IMPL(1,end_impl)
Chris@16: 
Chris@16: }}
Chris@16: 
Chris@16: #endif // BOOST_MPL_AUX_BEGIN_END_IMPL_HPP_INCLUDED