1/* Copyright 2003-2015 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/multi_index for library home page.
7 */
8
9#ifndef BOOST_MULTI_INDEX_MEMBER_HPP
10#define BOOST_MULTI_INDEX_MEMBER_HPP
11
12#if defined(_MSC_VER)
13#pragma once
14#endif
15
16#include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
17#include <boost/mpl/if.hpp>
18#include <boost/type_traits/is_const.hpp>
19#include <boost/utility/enable_if.hpp>
20#include <cstddef>
21
22#if !defined(BOOST_NO_SFINAE)
23#include <boost/type_traits/is_convertible.hpp>
24#endif
25
26namespace boost{
27
28template<class T> class reference_wrapper; /* fwd decl. */
29
30namespace multi_index{
31
32namespace detail{
33
34/* member is a read/write key extractor for accessing a given
35 * member of a class.
36 * Additionally, member is overloaded to support referece_wrappers
37 * of T and "chained pointers" to T's. By chained pointer to T we mean
38 * a type P such that, given a p of Type P
39 * *...n...*x is convertible to T&, for some n>=1.
40 * Examples of chained pointers are raw and smart pointers, iterators and
41 * arbitrary combinations of these (vg. T** or unique_ptr<T*>.)
42 */
43
44template<class Class,typename Type,Type Class::*PtrToMember>
45struct const_member_base
46{
47 typedef Type result_type;
48
49 template<typename ChainedPtr>
50
51#if !defined(BOOST_NO_SFINAE)
52 typename disable_if<
53 is_convertible<const ChainedPtr&,const Class&>,Type&>::type
54#else
55 Type&
56#endif
57
58 operator()(const ChainedPtr& x)const
59 {
60 return operator()(*x);
61 }
62
63 Type& operator()(const Class& x)const
64 {
65 return x.*PtrToMember;
66 }
67
68 Type& operator()(const reference_wrapper<const Class>& x)const
69 {
70 return operator()(x.get());
71 }
72
73 Type& operator()(const reference_wrapper<Class>& x)const
74 {
75 return operator()(x.get());
76 }
77};
78
79template<class Class,typename Type,Type Class::*PtrToMember>
80struct non_const_member_base
81{
82 typedef Type result_type;
83
84 template<typename ChainedPtr>
85
86#if !defined(BOOST_NO_SFINAE)
87 typename disable_if<
88 is_convertible<const ChainedPtr&,const Class&>,Type&>::type
89#else
90 Type&
91#endif
92
93 operator()(const ChainedPtr& x)const
94 {
95 return operator()(*x);
96 }
97
98 const Type& operator()(const Class& x)const
99 {
100 return x.*PtrToMember;
101 }
102
103 Type& operator()(Class& x)const
104 {
105 return x.*PtrToMember;
106 }
107
108 const Type& operator()(const reference_wrapper<const Class>& x)const
109 {
110 return operator()(x.get());
111 }
112
113 Type& operator()(const reference_wrapper<Class>& x)const
114 {
115 return operator()(x.get());
116 }
117};
118
119} /* namespace multi_index::detail */
120
121template<class Class,typename Type,Type Class::*PtrToMember>
122struct member:
123 mpl::if_c<
124 is_const<Type>::value,
125 detail::const_member_base<Class,Type,PtrToMember>,
126 detail::non_const_member_base<Class,Type,PtrToMember>
127 >::type
128{
129};
130
131namespace detail{
132
133/* MSVC++ 6.0 does not support properly pointers to members as
134 * non-type template arguments, as reported in
135 * http://support.microsoft.com/default.aspx?scid=kb;EN-US;249045
136 * A similar problem (though not identical) is shown by MSVC++ 7.0.
137 * We provide an alternative to member<> accepting offsets instead
138 * of pointers to members. This happens to work even for non-POD
139 * types (although the standard forbids use of offsetof on these),
140 * so it serves as a workaround in this compiler for all practical
141 * purposes.
142 * Surprisingly enough, other compilers, like Intel C++ 7.0/7.1 and
143 * Visual Age 6.0, have similar bugs. This replacement of member<>
144 * can be used for them too.
145 *
146 * Support for such old compilers is dropped and
147 * [non_]const_member_offset_base is deprecated.
148 */
149
150template<class Class,typename Type,std::size_t OffsetOfMember>
151struct const_member_offset_base
152{
153 typedef Type result_type;
154
155 template<typename ChainedPtr>
156
157#if !defined(BOOST_NO_SFINAE)
158 typename disable_if<
159 is_convertible<const ChainedPtr&,const Class&>,Type&>::type
160#else
161 Type&
162#endif
163
164 operator()(const ChainedPtr& x)const
165 {
166 return operator()(*x);
167 }
168
169 Type& operator()(const Class& x)const
170 {
171 return *static_cast<const Type*>(
172 static_cast<const void*>(
173 static_cast<const char*>(
174 static_cast<const void *>(&x))+OffsetOfMember));
175 }
176
177 Type& operator()(const reference_wrapper<const Class>& x)const
178 {
179 return operator()(x.get());
180 }
181
182 Type& operator()(const reference_wrapper<Class>& x)const
183 {
184 return operator()(x.get());
185 }
186};
187
188template<class Class,typename Type,std::size_t OffsetOfMember>
189struct non_const_member_offset_base
190{
191 typedef Type result_type;
192
193 template<typename ChainedPtr>
194
195#if !defined(BOOST_NO_SFINAE)
196 typename disable_if<
197 is_convertible<const ChainedPtr&,const Class&>,Type&>::type
198#else
199 Type&
200#endif
201
202 operator()(const ChainedPtr& x)const
203 {
204 return operator()(*x);
205 }
206
207 const Type& operator()(const Class& x)const
208 {
209 return *static_cast<const Type*>(
210 static_cast<const void*>(
211 static_cast<const char*>(
212 static_cast<const void *>(&x))+OffsetOfMember));
213 }
214
215 Type& operator()(Class& x)const
216 {
217 return *static_cast<Type*>(
218 static_cast<void*>(
219 static_cast<char*>(static_cast<void *>(&x))+OffsetOfMember));
220 }
221
222 const Type& operator()(const reference_wrapper<const Class>& x)const
223 {
224 return operator()(x.get());
225 }
226
227 Type& operator()(const reference_wrapper<Class>& x)const
228 {
229 return operator()(x.get());
230 }
231};
232
233} /* namespace multi_index::detail */
234
235template<class Class,typename Type,std::size_t OffsetOfMember>
236struct member_offset:
237 mpl::if_c<
238 is_const<Type>::value,
239 detail::const_member_offset_base<Class,Type,OffsetOfMember>,
240 detail::non_const_member_offset_base<Class,Type,OffsetOfMember>
241 >::type
242{
243};
244
245/* BOOST_MULTI_INDEX_MEMBER resolves to member in the normal cases,
246 * and to member_offset as a workaround in those defective compilers for
247 * which BOOST_NO_POINTER_TO_MEMBER_TEMPLATE_PARAMETERS is defined.
248 */
249
250#if defined(BOOST_NO_POINTER_TO_MEMBER_TEMPLATE_PARAMETERS)
251#define BOOST_MULTI_INDEX_MEMBER(Class,Type,MemberName) \
252::boost::multi_index::member_offset< Class,Type,offsetof(Class,MemberName) >
253#else
254#define BOOST_MULTI_INDEX_MEMBER(Class,Type,MemberName) \
255::boost::multi_index::member< Class,Type,&Class::MemberName >
256#endif
257
258} /* namespace multi_index */
259
260} /* namespace boost */
261
262#endif
263