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
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
|
/**
@file Pointer.h
@maintainer Morgan McGuire, http://graphics.cs.williams.edu
@created 2007-05-16
@edited 2009-03-26
Copyright 2000-2009, Morgan McGuire.
All rights reserved.
*/
#ifndef G3D_Pointer_h
#define G3D_Pointer_h
#include "G3D/debugAssert.h"
#include "G3D/ReferenceCount.h"
namespace G3D {
/**
Acts like a pointer to a value of type ValueType (i.e.,
ValueType*), but can operate through accessor methods as well as on
a value in memory. This is useful for implementing scripting
languages and other applications that need to connect existing APIs
by reference.
Because the accessors require values to be passed by value (instead of by reference)
this is primarily useful for objects whose memory size is small.
<pre>
class Foo {
public:
void setEnabled(bool b);
bool getEnabled() const;
};
Foo f;
bool b;
Pointer<bool> p1(&b);
Pointer<bool> p2(&f, &Foo::getEnabled, &Foo::setEnabled);
*p1 = true;
*p2 = false;
*p2 = *p1; \/\/ Value assignment
p2 = p1; \/\/ Pointer aliasing
\/\/ Or, equivalently:
p1.setValue(true);
p2.setValue(false);
p2.setValue(p1.getValue());
p2 = p1;
</pre>
<i>Note:</i> Because of the way that dereference is implemented, you cannot pass <code>*p</code> through a function
that takes varargs (...), e.g., <code>printf("%d", *p)</code> will produce a compile-time error. Instead use
<code>printf("%d",(bool)*p)</code> or <code>printf("%d", p.getValue())</code>.
*/
template<class ValueType>
class Pointer {
private:
class Interface {
public:
virtual ~Interface() {};
virtual void set(ValueType b) = 0;
virtual ValueType get() const = 0;
virtual Interface* clone() const = 0;
virtual bool isNull() const = 0;
};
class Memory : public Interface {
private:
ValueType* value;
public:
Memory(ValueType* value) : value(value) {
//debugAssert(value != NULL);
}
virtual void set(ValueType v) {
*value = v;
}
virtual ValueType get() const {
return *value;
}
virtual Interface* clone() const {
return new Memory(value);
}
virtual bool isNull() const {
return value == NULL;
}
};
template<class T, typename GetMethod, typename SetMethod>
class Accessor : public Interface {
private:
T* object;
GetMethod getMethod;
SetMethod setMethod;
public:
Accessor(T* object,
GetMethod getMethod,
SetMethod setMethod) : object(object), getMethod(getMethod), setMethod(setMethod) {
debugAssert(object != NULL);
}
virtual void set(ValueType v) {
(object->*setMethod)(v);
}
virtual ValueType get() const {
return (object->*getMethod)();
}
virtual Interface* clone() const {
return new Accessor(object, getMethod, setMethod);
}
virtual bool isNull() const {
return object == NULL;
}
};
template<class T, typename GetMethod, typename SetMethod>
class RefAccessor : public Interface {
private:
ReferenceCountedPointer<T> object;
GetMethod getMethod;
SetMethod setMethod;
public:
RefAccessor(
const ReferenceCountedPointer<T>& object,
GetMethod getMethod,
SetMethod setMethod) : object(object), getMethod(getMethod), setMethod(setMethod) {
debugAssert(object != NULL);
}
virtual void set(ValueType v) {
(object.pointer()->*setMethod)(v);
}
virtual ValueType get() const {
return (object.pointer()->*getMethod)();
}
virtual Interface* clone() const {
return new RefAccessor(object, getMethod, setMethod);
}
virtual bool isNull() const {
return object.isNull();
}
};
Interface* m_interface;
public:
Pointer() : m_interface(NULL) {};
/** Allows implicit cast from real pointer */
Pointer(ValueType* v) : m_interface(new Memory(v)) {}
inline bool isNull() const {
return (m_interface == NULL) || m_interface->isNull();
}
// Assignment
inline Pointer& operator=(const Pointer& r) {
delete m_interface;
if (r.m_interface != NULL) {
m_interface = r.m_interface->clone();
} else {
m_interface = NULL;
}
return this[0];
}
Pointer(const Pointer& p) : m_interface(NULL) {
this[0] = p;
}
template<class Class>
Pointer(const ReferenceCountedPointer<Class>& object,
ValueType (Class::*getMethod)() const,
void (Class::*setMethod)(ValueType)) :
m_interface(new RefAccessor<Class, ValueType (Class::*)() const, void (Class::*)(ValueType)>(object, getMethod, setMethod)) {}
template<class Class>
Pointer(const ReferenceCountedPointer<Class>& object,
const ValueType& (Class::*getMethod)() const,
void (Class::*setMethod)(ValueType)) :
m_interface(new RefAccessor<Class, const ValueType& (Class::*)() const, void (Class::*)(ValueType)>(object, getMethod, setMethod)) {}
template<class Class>
Pointer(const ReferenceCountedPointer<Class>& object,
ValueType (Class::*getMethod)() const,
void (Class::*setMethod)(const ValueType&)) :
m_interface(new RefAccessor<Class, ValueType (Class::*)() const, void (Class::*)(const ValueType&)>(object, getMethod, setMethod)) {}
template<class Class>
Pointer(const ReferenceCountedPointer<Class>& object,
const ValueType& (Class::*getMethod)() const,
void (Class::*setMethod)(const ValueType&)) :
m_interface(new RefAccessor<Class, const ValueType& (Class::*)() const, void (Class::*)(const ValueType&)>(object, getMethod, setMethod)) {}
template<class Class>
Pointer(Class* object,
const ValueType& (Class::*getMethod)() const,
void (Class::*setMethod)(const ValueType&)) :
m_interface(new Accessor<Class, const ValueType& (Class::*)() const, void (Class::*)(const ValueType&)>(object, getMethod, setMethod)) {}
template<class Class>
Pointer(Class* object,
ValueType (Class::*getMethod)() const,
void (Class::*setMethod)(const ValueType&)) :
m_interface(new Accessor<Class, ValueType (Class::*)() const, void (Class::*)(const ValueType&)>(object, getMethod, setMethod)) {}
template<class Class>
Pointer(Class* object,
const ValueType& (Class::*getMethod)() const,
void (Class::*setMethod)(ValueType)) :
m_interface(new Accessor<Class, const ValueType& (Class::*)() const, void (Class::*)(ValueType)>(object, getMethod, setMethod)) {}
template<class Class>
Pointer(Class* object,
ValueType (Class::*getMethod)() const,
void (Class::*setMethod)(ValueType)) :
m_interface(new Accessor<Class, ValueType (Class::*)() const, void (Class::*)(ValueType)>(object, getMethod, setMethod)) {}
~Pointer() {
delete m_interface;
}
inline const ValueType getValue() const {
debugAssert(m_interface != NULL);
return m_interface->get();
}
inline void setValue(const ValueType& v) {
debugAssert(m_interface != NULL);
m_interface->set(v);
}
class IndirectValue {
private:
friend class Pointer;
Pointer* pointer;
IndirectValue(Pointer* p) : pointer(p) {}
public:
void operator=(const ValueType& v) {
pointer->setValue(v);
}
operator ValueType() const {
return pointer->getValue();
}
};
inline IndirectValue operator*() {
return IndirectValue(this);
}
inline const ValueType operator*() const {
return getValue();
}
};
}
#endif
|
