poly_collection/detail/base_model.hpp

0001 /* Copyright 2016-2024 Joaquin M Lopez Munoz.
0002  * Distributed under the Boost Software License, Version 1.0.
0003  * (See accompanying file LICENSE_1_0.txt or copy at
0004  * http://www.boost.org/LICENSE_1_0.txt)
0005  *
0006  * See http://www.boost.org/libs/poly_collection for library home page.
0007  */
0008
0009 #ifndef BOOST_POLY_COLLECTION_DETAIL_BASE_MODEL_HPP
0010 #define BOOST_POLY_COLLECTION_DETAIL_BASE_MODEL_HPP
0011
0012 #if defined(_MSC_VER)
0013 #pragma once
0014 #endif
0015
0016 #include <boost/core/addressof.hpp>
0017 #include <boost/poly_collection/detail/is_final.hpp>
0018 #include <boost/poly_collection/detail/packed_segment.hpp>
0019 #include <boost/poly_collection/detail/stride_iterator.hpp>
0020 #include <memory>
0021 #include <type_traits>
0022 #include <typeinfo>
0023 #include <utility>
0024
0025 namespace boost{
0026
0027 namespace poly_collection{
0028
0029 namespace detail{
0030
0031 /* model for base_collection */
0032
0033 template<typename Base>
0034 struct base_model
0035 {
0036   using value_type=Base;
0037   using type_index=std::type_info;
0038   template<typename Derived>
0039   using is_implementation=std::is_base_of<Base,Derived>;
0040   template<typename T>
0041   using is_terminal=is_final<T>; //TODO: should we say !is_polymorhpic||is_final?
0042
0043 private:
0044   template<typename T>
0045   using enable_if_not_terminal=
0046     typename std::enable_if<!is_terminal<T>::value>::type*;
0047   template<typename T>
0048   using enable_if_terminal=
0049     typename std::enable_if<is_terminal<T>::value>::type*;
0050
0051 public:
0052   template<typename T>
0053   static const std::type_info& index(){return typeid(T);}
0054
0055   template<typename T,enable_if_not_terminal<T> =nullptr>
0056   static const std::type_info& subindex(const T& x){return typeid(x);}
0057
0058   template<typename T,enable_if_terminal<T> =nullptr>
0059   static const std::type_info& subindex(const T&){return typeid(T);}
0060
0061   template<typename T,enable_if_not_terminal<T> =nullptr>
0062   static void* subaddress(T& x)
0063   {
0064     return dynamic_cast<void*>(boost::addressof(x));
0065   }
0066
0067   template<typename T,enable_if_not_terminal<T> =nullptr>
0068   static const void* subaddress(const T& x)
0069   {
0070     return dynamic_cast<const void*>(boost::addressof(x));
0071   }
0072
0073   template<typename T,enable_if_terminal<T> =nullptr>
0074   static void* subaddress(T& x){return boost::addressof(x);}
0075
0076   template<typename T,enable_if_terminal<T> =nullptr>
0077   static const void* subaddress(const T& x){return boost::addressof(x);}
0078
0079   using base_iterator=stride_iterator<Base>;
0080   using const_base_iterator=stride_iterator<const Base>;
0081   using base_sentinel=Base*;
0082   using const_base_sentinel=const Base*;
0083   template<typename Derived>
0084   using iterator=Derived*;
0085   template<typename Derived>
0086   using const_iterator=const Derived*;
0087   template<typename Allocator>
0088   using segment_backend=detail::segment_backend<base_model,Allocator>;
0089   template<typename Derived,typename Allocator>
0090   using segment_backend_implementation=
0091     packed_segment<base_model,Derived,Allocator>;
0092
0093   static base_iterator nonconst_iterator(const_base_iterator it)
0094   {
0095     return {
0096       const_cast<value_type*>(static_cast<const value_type*>(it)),
0097       it.stride()
0098     };
0099   }
0100
0101   template<typename T>
0102   static iterator<T> nonconst_iterator(const_iterator<T> it)
0103   {
0104     return const_cast<iterator<T>>(it);
0105   }
0106
0107 private:
0108   template<typename,typename,typename>
0109   friend class packed_segment;
0110
0111   template<typename Derived>
0112   static const Base* value_ptr(const Derived* p)noexcept
0113   {
0114     return p;
0115   }
0116 };
0117
0118 } /* namespace poly_collection::detail */
0119
0120 } /* namespace poly_collection */
0121
0122 } /* namespace boost */
0123
0124 #endif