1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
|
/*! \file base_class.hpp
\brief Support for base classes (virtual and non-virtual)
\ingroup OtherTypes */
/*
Copyright (c) 2014, Randolph Voorhies, Shane Grant
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* Neither the name of the copyright holder nor the
names of its contributors may be used to endorse or promote products
derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef CEREAL_TYPES_BASE_CLASS_HPP_
#define CEREAL_TYPES_BASE_CLASS_HPP_
#include "cereal/details/traits.hpp"
#include "cereal/details/polymorphic_impl_fwd.hpp"
namespace cereal
{
namespace base_class_detail
{
//! Used to register polymorphic relations and avoid the need to include
//! polymorphic.hpp when no polymorphism is used
/*! @internal */
template <class Base, class Derived, bool IsPolymorphic = std::is_polymorphic<Base>::value>
struct RegisterPolymorphicBaseClass
{
static void bind()
{ }
};
//! Polymorphic version
/*! @internal */
template <class Base, class Derived>
struct RegisterPolymorphicBaseClass<Base, Derived, true>
{
static void bind()
{ detail::RegisterPolymorphicCaster<Base, Derived>::bind(); }
};
}
//! Casts a derived class to its non-virtual base class in a way that safely supports abstract classes
/*! This should be used in cases when a derived type needs to serialize its base type. This is better than directly
using static_cast, as it allows for serialization of pure virtual (abstract) base classes.
This also automatically registers polymorphic relation between the base and derived class, assuming they
are indeed polymorphic. Note this is not the same as polymorphic type registration. For more information
see the documentation on polymorphism. If using a polymorphic class, be sure to include support for
polymorphism (cereal/types/polymorphic.hpp).
\sa virtual_base_class
@code{.cpp}
struct MyBase
{
int x;
virtual void foo() = 0;
template <class Archive>
void serialize( Archive & ar )
{
ar( x );
}
};
struct MyDerived : public MyBase //<-- Note non-virtual inheritance
{
int y;
virtual void foo() {};
template <class Archive>
void serialize( Archive & ar )
{
ar( cereal::base_class<MyBase>(this) );
ar( y );
}
};
@endcode */
template<class Base>
struct base_class : private traits::detail::BaseCastBase
{
template<class Derived>
base_class(Derived const * derived) :
base_ptr(const_cast<Base*>(static_cast<Base const *>(derived)))
{
static_assert( std::is_base_of<Base, Derived>::value, "Can only use base_class on a valid base class" );
base_class_detail::RegisterPolymorphicBaseClass<Base, Derived>::bind();
}
Base * base_ptr;
};
//! Casts a derived class to its virtual base class in a way that allows cereal to track inheritance
/*! This should be used in cases when a derived type features virtual inheritance from some
base type. This allows cereal to track the inheritance and to avoid making duplicate copies
during serialization.
It is safe to use virtual_base_class in all circumstances for serializing base classes, even in cases
where virtual inheritance does not take place, though it may be slightly faster to utilize
cereal::base_class<> if you do not need to worry about virtual inheritance.
This also automatically registers polymorphic relation between the base and derived class, assuming they
are indeed polymorphic. Note this is not the same as polymorphic type registration. For more information
see the documentation on polymorphism. If using a polymorphic class, be sure to include support for
polymorphism (cereal/types/polymorphic.hpp).
\sa base_class
@code{.cpp}
struct MyBase
{
int x;
template <class Archive>
void serialize( Archive & ar )
{
ar( x );
}
};
struct MyLeft : virtual MyBase //<-- Note the virtual inheritance
{
int y;
template <class Archive>
void serialize( Archive & ar )
{
ar( cereal::virtual_base_class<MyBase>( this ) );
ar( y );
}
};
struct MyRight : virtual MyBase
{
int z;
template <class Archive>
void serialize( Archive & ar )
{
ar( cereal::virtual_base_clas<MyBase>( this ) );
ar( z );
}
};
// diamond virtual inheritance; contains one copy of each base class
struct MyDerived : virtual MyLeft, virtual MyRight
{
int a;
template <class Archive>
void serialize( Archive & ar )
{
ar( cereal::virtual_base_class<MyLeft>( this ) ); // safely serialize data members in MyLeft
ar( cereal::virtual_base_class<MyRight>( this ) ); // safely serialize data members in MyRight
ar( a );
// Because we used virtual_base_class, cereal will ensure that only one instance of MyBase is
// serialized as we traverse the inheritance heirarchy. This means that there will be one copy
// each of the variables x, y, z, and a
// If we had chosen to use static_cast<> instead, cereal would perform no tracking and
// assume that every base class should be serialized (in this case leading to a duplicate
// serialization of MyBase due to diamond inheritance
};
}
@endcode */
template<class Base>
struct virtual_base_class : private traits::detail::BaseCastBase
{
template<class Derived>
virtual_base_class(Derived const * derived) :
base_ptr(const_cast<Base*>(static_cast<Base const *>(derived)))
{
static_assert( std::is_base_of<Base, Derived>::value, "Can only use virtual_base_class on a valid base class" );
base_class_detail::RegisterPolymorphicBaseClass<Base, Derived>::bind();
}
Base * base_ptr;
};
} // namespace cereal
#endif // CEREAL_TYPES_BASE_CLASS_HPP_
|
