1 /* Copyright 2016-2018 Joaquin M Lopez Munoz.
2  * Distributed under the Boost Software License, Version 1.0.
3  * (See accompanying file LICENSE_1_0.txt or copy at
4  * http://www.boost.org/LICENSE_1_0.txt)
5  *
6  * See http://www.boost.org/libs/poly_collection for library home page.
7  */
8 
9 #ifndef BOOST_POLY_COLLECTION_DETAIL_BASE_MODEL_HPP
10 #define BOOST_POLY_COLLECTION_DETAIL_BASE_MODEL_HPP
11 
12 #if defined(_MSC_VER)
13 #pragma once
14 #endif
15 
16 #include <boost/core/addressof.hpp>
17 #include <boost/poly_collection/detail/is_final.hpp>
18 #include <boost/poly_collection/detail/packed_segment.hpp>
19 #include <boost/poly_collection/detail/stride_iterator.hpp>
20 #include <memory>
21 #include <type_traits>
22 #include <typeinfo>
23 #include <utility>
24 
25 namespace boost{
26 
27 namespace poly_collection{
28 
29 namespace detail{
30 
31 /* model for base_collection */
32 
33 template<typename Base>
34 struct base_model
35 {
36   using value_type=Base;
37   template<typename Derived>
38   using is_implementation=std::is_base_of<Base,Derived>;
39   template<typename T>
40   using is_terminal=is_final<T>; //TODO: should we say !is_polymorhpic||is_final?
41 
42 private:
43   template<typename T>
44   using enable_if_not_terminal=
45     typename std::enable_if<!is_terminal<T>::value>::type*;
46   template<typename T>
47   using enable_if_terminal=
48     typename std::enable_if<is_terminal<T>::value>::type*;
49 
50 public:
51   template<typename T,enable_if_not_terminal<T> =nullptr>
subtypeidboost::poly_collection::detail::base_model52   static const std::type_info& subtypeid(const T& x){return typeid(x);}
53 
54   template<typename T,enable_if_terminal<T> =nullptr>
subtypeidboost::poly_collection::detail::base_model55   static const std::type_info& subtypeid(const T&){return typeid(T);}
56 
57   template<typename T,enable_if_not_terminal<T> =nullptr>
subaddressboost::poly_collection::detail::base_model58   static void* subaddress(T& x)
59   {
60     return dynamic_cast<void*>(boost::addressof(x));
61   }
62 
63   template<typename T,enable_if_not_terminal<T> =nullptr>
subaddressboost::poly_collection::detail::base_model64   static const void* subaddress(const T& x)
65   {
66     return dynamic_cast<const void*>(boost::addressof(x));
67   }
68 
69   template<typename T,enable_if_terminal<T> =nullptr>
subaddressboost::poly_collection::detail::base_model70   static void* subaddress(T& x){return boost::addressof(x);}
71 
72   template<typename T,enable_if_terminal<T> =nullptr>
subaddressboost::poly_collection::detail::base_model73   static const void* subaddress(const T& x){return boost::addressof(x);}
74 
75   using base_iterator=stride_iterator<Base>;
76   using const_base_iterator=stride_iterator<const Base>;
77   using base_sentinel=Base*;
78   using const_base_sentinel=const Base*;
79   template<typename Derived>
80   using iterator=Derived*;
81   template<typename Derived>
82   using const_iterator=const Derived*;
83   template<typename Allocator>
84   using segment_backend=detail::segment_backend<base_model,Allocator>;
85   template<typename Derived,typename Allocator>
86   using segment_backend_implementation=
87     packed_segment<base_model,Derived,Allocator>;
88 
nonconst_iteratorboost::poly_collection::detail::base_model89   static base_iterator nonconst_iterator(const_base_iterator it)
90   {
91     return {
92       const_cast<value_type*>(static_cast<const value_type*>(it)),
93       it.stride()
94     };
95   }
96 
97   template<typename T>
nonconst_iteratorboost::poly_collection::detail::base_model98   static iterator<T> nonconst_iterator(const_iterator<T> it)
99   {
100     return const_cast<iterator<T>>(it);
101   }
102 
103 private:
104   template<typename,typename,typename>
105   friend class packed_segment;
106 
107   template<typename Derived>
value_ptrboost::poly_collection::detail::base_model108   static const Base* value_ptr(const Derived* p)noexcept
109   {
110     return p;
111   }
112 };
113 
114 } /* namespace poly_collection::detail */
115 
116 } /* namespace poly_collection */
117 
118 } /* namespace boost */
119 
120 #endif
121