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
|
////////////////////////////////////////////////////////////////////////////////
// The Loki Library
// Copyright (c) 2001 by Andrei Alexandrescu
// This code accompanies the book:
// Alexandrescu, Andrei. "Modern C++ Design: Generic Programming and Design
// Patterns Applied". Copyright (c) 2001. Addison-Wesley.
// Permission to use, copy, modify, distribute and sell this software for any
// purpose is hereby granted without fee, provided that the above copyright
// notice appear in all copies and that both that copyright notice and this
// permission notice appear in supporting documentation.
// The author or Addison-Wesley Longman make no representations about the
// suitability of this software for any purpose. It is provided "as is"
// without express or implied warranty.
////////////////////////////////////////////////////////////////////////////////
#ifndef FACTORY_INC_
#define FACTORY_INC_
#include "LokiTypeInfo.h"
#include "AssocVector.h"
#include <exception>
namespace Loki
{
////////////////////////////////////////////////////////////////////////////////
// class template DefaultFactoryError
// Manages the "Unknown Type" error in an object factory
////////////////////////////////////////////////////////////////////////////////
template <typename IdentifierType, class AbstractProduct>
struct DefaultFactoryError
{
struct Exception : public std::exception
{
const char* what() const throw() { return "Unknown Type"; }
};
static AbstractProduct* OnUnknownType(IdentifierType)
{
throw Exception();
}
};
////////////////////////////////////////////////////////////////////////////////
// class template Factory
// Implements a generic object factory
////////////////////////////////////////////////////////////////////////////////
template
<
class AbstractProduct,
typename IdentifierType,
typename ProductCreator = AbstractProduct* (*)(),
template<typename, class>
class FactoryErrorPolicy = DefaultFactoryError
>
class Factory
: public FactoryErrorPolicy<IdentifierType, AbstractProduct>
{
public:
bool Register(const IdentifierType& id, ProductCreator creator)
{
return associations_.insert(
typename IdToProductMap::value_type(id, creator)).second;
}
bool Unregister(const IdentifierType& id)
{
return associations_.erase(id) == 1;
}
AbstractProduct* CreateObject(const IdentifierType& id)
{
typename IdToProductMap::iterator i = associations_.find(id);
if (i != associations_.end())
{
return (i->second)();
}
return this->OnUnknownType(id);
}
private:
typedef AssocVector<IdentifierType, ProductCreator> IdToProductMap;
IdToProductMap associations_;
};
////////////////////////////////////////////////////////////////////////////////
// class template CloneFactory
// Implements a generic cloning factory
////////////////////////////////////////////////////////////////////////////////
template
<
class AbstractProduct,
class ProductCreator =
AbstractProduct* (*)(const AbstractProduct*),
template<typename, class>
class FactoryErrorPolicy = DefaultFactoryError
>
class CloneFactory
: public FactoryErrorPolicy<TypeInfo, AbstractProduct>
{
public:
bool Register(const TypeInfo& ti, ProductCreator creator)
{
return associations_.insert(
typename IdToProductMap::value_type(ti, creator)).second;
}
bool Unregister(const TypeInfo& id)
{
return associations_.erase(id) == 1;
}
AbstractProduct* CreateObject(const AbstractProduct* model)
{
if (model == 0) return 0;
typename IdToProductMap::iterator i =
associations_.find(typeid(*model));
if (i != associations_.end())
{
return (i->second)(model);
}
return this->OnUnknownType(typeid(*model));
}
private:
typedef AssocVector<TypeInfo, ProductCreator> IdToProductMap;
IdToProductMap associations_;
};
} // namespace Loki
////////////////////////////////////////////////////////////////////////////////
// Change log:
// June 20, 2001: ported by Nick Thurn to gcc 2.95.3. Kudos, Nick!!!
// May 08, 2002: replaced const_iterator with iterator so that self-modifying
// ProductCreators are supported. Also, added a throw()
// spec to what(). Credit due to Jason Fischl.
// February 2, 2003: fixed dependent names - credit due to Rani Sharoni
// March 4, 2003: fixed dependent names - credit due to Ruslan Zasukhin and CW 8.3
////////////////////////////////////////////////////////////////////////////////
#endif // FACTORY_INC_
|
