#ifndef BOOST_MPL_AUX_BEGIN_END_IMPL_HPP_INCLUDED | |
#define BOOST_MPL_AUX_BEGIN_END_IMPL_HPP_INCLUDED | |
// Copyright Aleksey Gurtovoy 2000-2004 | |
// | |
// Distributed under the Boost Software License, Version 1.0. | |
// (See accompanying file LICENSE_1_0.txt or copy at | |
// http://www.boost.org/LICENSE_1_0.txt) | |
// | |
// See http://www.boost.org/libs/mpl for documentation. | |
// $Id: begin_end_impl.hpp 49267 2008-10-11 06:19:02Z agurtovoy $ | |
// $Date: 2008-10-11 02:19:02 -0400 (Sat, 11 Oct 2008) $ | |
// $Revision: 49267 $ | |
#include <boost/mpl/begin_end_fwd.hpp> | |
#include <boost/mpl/sequence_tag_fwd.hpp> | |
#include <boost/mpl/void.hpp> | |
#include <boost/mpl/eval_if.hpp> | |
#include <boost/mpl/aux_/has_begin.hpp> | |
#include <boost/mpl/aux_/na.hpp> | |
#include <boost/mpl/aux_/traits_lambda_spec.hpp> | |
#include <boost/mpl/aux_/config/eti.hpp> | |
namespace boost { namespace mpl { | |
namespace aux { | |
template< typename Sequence > | |
struct begin_type | |
{ | |
typedef typename Sequence::begin type; | |
}; | |
template< typename Sequence > | |
struct end_type | |
{ | |
typedef typename Sequence::end type; | |
}; | |
} | |
// default implementation; conrete sequences might override it by | |
// specializing either the 'begin_impl/end_impl' or the primary | |
// 'begin/end' templates | |
template< typename Tag > | |
struct begin_impl | |
{ | |
template< typename Sequence > struct apply | |
{ | |
typedef typename eval_if<aux::has_begin<Sequence, true_>, | |
aux::begin_type<Sequence>, void_>::type type; | |
}; | |
}; | |
template< typename Tag > | |
struct end_impl | |
{ | |
template< typename Sequence > struct apply | |
{ | |
typedef typename eval_if<aux::has_begin<Sequence, true_>, | |
aux::end_type<Sequence>, void_>::type type; | |
}; | |
}; | |
// specialize 'begin_trait/end_trait' for two pre-defined tags | |
# define AUX778076_IMPL_SPEC(name, tag, result) \ | |
template<> \ | |
struct name##_impl<tag> \ | |
{ \ | |
template< typename Sequence > struct apply \ | |
{ \ | |
typedef result type; \ | |
}; \ | |
}; \ | |
/**/ | |
// a sequence with nested 'begin/end' typedefs; just query them | |
AUX778076_IMPL_SPEC(begin, nested_begin_end_tag, typename Sequence::begin) | |
AUX778076_IMPL_SPEC(end, nested_begin_end_tag, typename Sequence::end) | |
// if a type 'T' does not contain 'begin/end' or 'tag' members | |
// and doesn't specialize either 'begin/end' or 'begin_impl/end_impl' | |
// templates, then we end up here | |
AUX778076_IMPL_SPEC(begin, non_sequence_tag, void_) | |
AUX778076_IMPL_SPEC(end, non_sequence_tag, void_) | |
AUX778076_IMPL_SPEC(begin, na, void_) | |
AUX778076_IMPL_SPEC(end, na, void_) | |
# undef AUX778076_IMPL_SPEC | |
BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC_IMPL(1,begin_impl) | |
BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC_IMPL(1,end_impl) | |
}} | |
#endif // BOOST_MPL_AUX_BEGIN_END_IMPL_HPP_INCLUDED |