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 // $Id: begin_end_impl.hpp 49267 2008-10-11 06:19:02Z agurtovoy $
14 // $Date: 2008-10-10 23:19:02 -0700 (Fri, 10 Oct 2008) $
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 {
31 template< typename Sequence >
34 typedef typename Sequence::begin type;
36 template< typename Sequence >
39 typedef typename Sequence::end type;
44 // default implementation; conrete sequences might override it by
45 // specializing either the 'begin_impl/end_impl' or the primary
46 // 'begin/end' templates
48 template< typename Tag >
51 template< typename Sequence > struct apply
53 typedef typename eval_if<aux::has_begin<Sequence, true_>,
54 aux::begin_type<Sequence>, void_>::type type;
58 template< typename Tag >
61 template< typename Sequence > struct apply
63 typedef typename eval_if<aux::has_begin<Sequence, true_>,
64 aux::end_type<Sequence>, void_>::type type;
68 // specialize 'begin_trait/end_trait' for two pre-defined tags
70 # define AUX778076_IMPL_SPEC(name, tag, result) \
72 struct name##_impl<tag> \
74 template< typename Sequence > struct apply \
76 typedef result type; \
81 // a sequence with nested 'begin/end' typedefs; just query them
82 AUX778076_IMPL_SPEC(begin, nested_begin_end_tag, typename Sequence::begin)
83 AUX778076_IMPL_SPEC(end, nested_begin_end_tag, typename Sequence::end)
85 // if a type 'T' does not contain 'begin/end' or 'tag' members
86 // and doesn't specialize either 'begin/end' or 'begin_impl/end_impl'
87 // templates, then we end up here
88 AUX778076_IMPL_SPEC(begin, non_sequence_tag, void_)
89 AUX778076_IMPL_SPEC(end, non_sequence_tag, void_)
90 AUX778076_IMPL_SPEC(begin, na, void_)
91 AUX778076_IMPL_SPEC(end, na, void_)
93 # undef AUX778076_IMPL_SPEC
96 BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC_IMPL(1,begin_impl)
97 BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC_IMPL(1,end_impl)
101 #endif // BOOST_MPL_AUX_BEGIN_END_IMPL_HPP_INCLUDED