2 #ifndef BOOST_MPL_AUX_BEGIN_END_IMPL_HPP_INCLUDED
3 #define BOOST_MPL_AUX_BEGIN_END_IMPL_HPP_INCLUDED
5 // Copyright Aleksey Gurtovoy 2000-2004
7 // Distributed under the Boost Software License, Version 1.0.
8 // (See accompanying file LICENSE_1_0.txt or copy at
9 // http://www.boost.org/LICENSE_1_0.txt)
11 // See http://www.boost.org/libs/mpl for documentation.
13 // $Source: /cvsroot/boost/boost/boost/mpl/aux_/begin_end_impl.hpp,v $
14 // $Date: 2006/07/22 15:08:37 $
15 // $Revision: 1.8.14.1 $
17 #include <boost/mpl/begin_end_fwd.hpp>
18 #include <boost/mpl/sequence_tag_fwd.hpp>
19 #include <boost/mpl/void.hpp>
20 #include <boost/mpl/eval_if.hpp>
21 #include <boost/mpl/aux_/has_begin.hpp>
22 #include <boost/mpl/aux_/na.hpp>
23 #include <boost/mpl/aux_/traits_lambda_spec.hpp>
24 #include <boost/mpl/aux_/config/eti.hpp>
26 namespace boost { namespace mpl {
30 template< typename Sequence >
33 typedef typename Sequence::begin type;
35 template< typename Sequence >
38 typedef typename Sequence::end type;
43 // default implementation; conrete sequences might override it by
44 // specializing either the 'begin_impl/end_impl' or the primary
45 // 'begin/end' templates
47 template< typename Tag >
50 template< typename Sequence > struct apply
52 typedef typename eval_if<aux::has_begin<Sequence, true_>,
53 aux::begin_type<Sequence>, void_>::type type;
57 template< typename Tag >
60 template< typename Sequence > struct apply
62 typedef typename eval_if<aux::has_begin<Sequence, true_>,
63 aux::end_type<Sequence>, void_>::type type;
67 // specialize 'begin_trait/end_trait' for two pre-defined tags
69 # define AUX778076_IMPL_SPEC(name, tag, result) \
71 struct name##_impl<tag> \
73 template< typename Sequence > struct apply \
75 typedef result type; \
80 // a sequence with nested 'begin/end' typedefs; just query them
81 AUX778076_IMPL_SPEC(begin, nested_begin_end_tag, typename Sequence::begin)
82 AUX778076_IMPL_SPEC(end, nested_begin_end_tag, typename Sequence::end)
84 // if a type 'T' does not contain 'begin/end' or 'tag' members
85 // and doesn't specialize either 'begin/end' or 'begin_impl/end_impl'
86 // templates, then we end up here
87 AUX778076_IMPL_SPEC(begin, non_sequence_tag, void_)
88 AUX778076_IMPL_SPEC(end, non_sequence_tag, void_)
89 AUX778076_IMPL_SPEC(begin, na, void_)
90 AUX778076_IMPL_SPEC(end, na, void_)
92 # undef AUX778076_IMPL_SPEC
95 BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC(1,begin_impl)
96 BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC(1,end_impl)
100 #endif // BOOST_MPL_AUX_BEGIN_END_IMPL_HPP_INCLUDED