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