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162 lines
4.5 KiB
162 lines
4.5 KiB
//----------------------------------------------------------------------------- |
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// boost variant/detail/enable_recursive.hpp header file |
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// See http://www.boost.org for updates, documentation, and revision history. |
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//----------------------------------------------------------------------------- |
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// |
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// Copyright (c) 2003 |
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// Eric Friedman |
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// |
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// Distributed under the Boost Software License, Version 1.0. (See |
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// 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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#ifndef BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_HPP |
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#define BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_HPP |
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#include "boost/variant/detail/enable_recursive_fwd.hpp" |
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#include "boost/variant/variant_fwd.hpp" |
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#if !defined(BOOST_VARIANT_NO_FULL_RECURSIVE_VARIANT_SUPPORT) |
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# include "boost/mpl/apply.hpp" |
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# include "boost/mpl/eval_if.hpp" |
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# include "boost/mpl/lambda.hpp" |
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#endif |
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#include "boost/variant/detail/substitute.hpp" |
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#include "boost/mpl/aux_/config/ctps.hpp" |
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#include "boost/mpl/bool_fwd.hpp" |
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#include "boost/mpl/if.hpp" |
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#include "boost/mpl/or.hpp" |
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#include "boost/type_traits/is_pointer.hpp" |
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#include "boost/type_traits/is_reference.hpp" |
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#include "boost/type_traits/is_same.hpp" |
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#include "boost/variant/recursive_wrapper.hpp" |
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namespace boost { |
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namespace detail { namespace variant { |
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#if !defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE) |
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# define BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL(T,Dest,Source) \ |
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substitute< T , Dest , Source > \ |
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/**/ |
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#else // defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE) |
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/////////////////////////////////////////////////////////////////////////////// |
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// (detail) class template rebind1 |
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// |
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// Limited workaround in case 'substitute' metafunction unavailable. |
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// |
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template <typename T, typename U1> |
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struct rebind1 |
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{ |
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private: |
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typedef typename mpl::lambda< |
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mpl::identity<T> |
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>::type le_; |
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public: |
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typedef typename mpl::eval_if< |
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is_same< le_, mpl::identity<T> > |
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, le_ // identity<T> |
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, mpl::apply1<le_, U1> |
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>::type type; |
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}; |
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# define BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL(T,Dest,Source) \ |
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rebind1< T , Dest > \ |
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/**/ |
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#endif // !defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE) |
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/////////////////////////////////////////////////////////////////////////////// |
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// (detail) metafunction enable_recursive |
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// |
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// See boost/variant/detail/enable_recursive_fwd.hpp for more information. |
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// |
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#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) |
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template <typename T, typename RecursiveVariant, typename NoWrapper> |
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struct enable_recursive |
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: BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL( |
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T, RecursiveVariant, ::boost::recursive_variant_ |
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) |
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{ |
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}; |
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template <typename T, typename RecursiveVariant> |
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struct enable_recursive< T,RecursiveVariant,mpl::false_ > |
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{ |
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private: // helpers, for metafunction result (below) |
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typedef typename BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL( |
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T, RecursiveVariant, ::boost::recursive_variant_ |
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)::type t_; |
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public: // metafunction result |
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// [Wrap with recursive_wrapper only if rebind really changed something:] |
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typedef typename mpl::if_< |
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mpl::or_< |
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is_same< t_,T > |
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, is_reference<t_> |
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, is_pointer<t_> |
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> |
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, t_ |
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, boost::recursive_wrapper<t_> |
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>::type type; |
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}; |
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#else // defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) |
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template <typename T, typename RecursiveVariant, typename NoWrapper> |
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struct enable_recursive |
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{ |
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private: // helpers, for metafunction result (below) |
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typedef typename BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL( |
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T, RecursiveVariant, ::boost::recursive_variant_ |
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)::type t_; |
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public: // metafunction result |
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// [Wrap with recursive_wrapper only if rebind really changed something:] |
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typedef typename mpl::if_< |
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mpl::or_< |
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NoWrapper |
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, is_same< t_,T > |
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, is_reference<t_> |
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, is_pointer<t_> |
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> |
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, t_ |
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, boost::recursive_wrapper<t_> |
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>::type type; |
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}; |
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#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION workaround |
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/////////////////////////////////////////////////////////////////////////////// |
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// (detail) metafunction class quoted_enable_recursive |
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// |
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// Same behavior as enable_recursive metafunction (see above). |
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// |
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template <typename RecursiveVariant, typename NoWrapper> |
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struct quoted_enable_recursive |
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{ |
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template <typename T> |
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struct apply |
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: enable_recursive<T, RecursiveVariant, NoWrapper> |
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{ |
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}; |
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}; |
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}} // namespace detail::variant |
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} // namespace boost |
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#endif // BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_HPP
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