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209 lines
5.9 KiB
209 lines
5.9 KiB
//----------------------------------------------------------------------------- |
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// boost variant/recursive_variant.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 Eric Friedman |
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// Copyright (c) 2013-2019 Antony Polukhin |
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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_RECURSIVE_VARIANT_HPP |
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#define BOOST_VARIANT_RECURSIVE_VARIANT_HPP |
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#include <boost/variant/variant_fwd.hpp> |
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#include <boost/variant/detail/enable_recursive.hpp> |
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#include <boost/variant/detail/substitute_fwd.hpp> |
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#include <boost/variant/detail/make_variant_list.hpp> |
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#include <boost/variant/detail/over_sequence.hpp> |
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#include <boost/mpl/aux_/lambda_arity_param.hpp> |
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#include <boost/mpl/equal.hpp> |
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#include <boost/mpl/eval_if.hpp> |
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#include <boost/mpl/identity.hpp> |
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#include <boost/mpl/if.hpp> |
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#include <boost/mpl/protect.hpp> |
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#include <boost/mpl/transform.hpp> |
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#include <boost/type_traits/is_same.hpp> |
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#include <boost/preprocessor/cat.hpp> |
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#include <boost/preprocessor/repeat.hpp> |
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#include <boost/mpl/bool.hpp> |
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#include <boost/mpl/is_sequence.hpp> |
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#include <boost/variant/variant.hpp> |
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namespace boost { |
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namespace detail { namespace variant { |
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/////////////////////////////////////////////////////////////////////////////// |
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// (detail) metafunction specialization substitute |
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// |
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// Handles embedded variant types when substituting for recursive_variant_. |
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// |
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#if !defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE) |
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template < |
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BOOST_VARIANT_ENUM_PARAMS(typename T) |
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, typename RecursiveVariant |
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BOOST_MPL_AUX_LAMBDA_ARITY_PARAM(typename Arity) |
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> |
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struct substitute< |
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::boost::variant< |
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recursive_flag< T0 > |
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, BOOST_VARIANT_ENUM_SHIFTED_PARAMS(T) |
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> |
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, RecursiveVariant |
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, ::boost::recursive_variant_ |
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BOOST_MPL_AUX_LAMBDA_ARITY_PARAM(Arity) |
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> |
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{ |
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typedef ::boost::variant< |
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recursive_flag< T0 > |
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, BOOST_VARIANT_ENUM_SHIFTED_PARAMS(T) |
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> type; |
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}; |
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template < |
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BOOST_VARIANT_ENUM_PARAMS(typename T) |
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, typename RecursiveVariant |
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BOOST_MPL_AUX_LAMBDA_ARITY_PARAM(typename Arity) |
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> |
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struct substitute< |
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::boost::variant< |
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::boost::detail::variant::over_sequence< T0 > |
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, BOOST_VARIANT_ENUM_SHIFTED_PARAMS(T) |
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> |
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, RecursiveVariant |
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, ::boost::recursive_variant_ |
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BOOST_MPL_AUX_LAMBDA_ARITY_PARAM(Arity) |
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> |
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{ |
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private: |
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typedef T0 initial_types; |
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typedef typename mpl::transform< |
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initial_types |
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, mpl::protect< quoted_enable_recursive<RecursiveVariant,mpl::true_> > |
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>::type types; |
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public: |
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typedef typename mpl::if_< |
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mpl::equal<initial_types, types, ::boost::is_same<mpl::_1, mpl::_2> > |
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, ::boost::variant< |
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::boost::detail::variant::over_sequence< T0 > |
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, BOOST_VARIANT_ENUM_SHIFTED_PARAMS(T) |
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> |
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, ::boost::variant< over_sequence<types> > |
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>::type type; |
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}; |
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template < |
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BOOST_VARIANT_ENUM_PARAMS(typename T) |
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, typename RecursiveVariant |
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BOOST_MPL_AUX_LAMBDA_ARITY_PARAM(typename Arity) |
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> |
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struct substitute< |
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::boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) > |
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, RecursiveVariant |
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, ::boost::recursive_variant_ |
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BOOST_MPL_AUX_LAMBDA_ARITY_PARAM(Arity) |
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> |
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{ |
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#if !defined(BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES) |
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typedef ::boost::variant< |
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typename enable_recursive< |
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T0 |
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, RecursiveVariant |
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, mpl::true_ |
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>::type, |
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typename enable_recursive< |
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TN |
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, RecursiveVariant |
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, mpl::true_ |
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>::type... |
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> type; |
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#else // defined(BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES) |
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private: // helpers, for metafunction result (below) |
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#define BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS(z,N,_) \ |
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typedef typename enable_recursive< \ |
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BOOST_PP_CAT(T,N) \ |
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, RecursiveVariant \ |
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, mpl::true_ \ |
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>::type BOOST_PP_CAT(wknd_T,N); \ |
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/**/ |
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BOOST_PP_REPEAT( |
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BOOST_VARIANT_LIMIT_TYPES |
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, BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS |
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, _ |
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) |
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#undef BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS |
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public: // metafunction result |
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typedef ::boost::variant< BOOST_VARIANT_ENUM_PARAMS(wknd_T) > type; |
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#endif // BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES workaround |
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}; |
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#else // defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE) |
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// |
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// no specializations: embedded variants unsupported on these compilers! |
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// |
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#endif // !defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE) |
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}} // namespace detail::variant |
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/////////////////////////////////////////////////////////////////////////////// |
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// metafunction make_recursive_variant |
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// |
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// See docs and boost/variant/variant_fwd.hpp for more information. |
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// |
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template < BOOST_VARIANT_ENUM_PARAMS(typename T) > |
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struct make_recursive_variant |
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{ |
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public: // metafunction result |
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typedef boost::variant< |
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detail::variant::recursive_flag< T0 > |
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, BOOST_VARIANT_ENUM_SHIFTED_PARAMS(T) |
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> type; |
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}; |
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/////////////////////////////////////////////////////////////////////////////// |
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// metafunction make_recursive_variant_over |
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// |
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// See docs and boost/variant/variant_fwd.hpp for more information. |
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// |
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template <typename Types> |
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struct make_recursive_variant_over |
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{ |
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private: // precondition assertions |
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BOOST_STATIC_ASSERT(( ::boost::mpl::is_sequence<Types>::value )); |
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public: // metafunction result |
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typedef typename make_recursive_variant< |
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detail::variant::over_sequence< Types > |
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>::type type; |
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}; |
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} // namespace boost |
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#endif // BOOST_VARIANT_RECURSIVE_VARIANT_HPP
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