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
|
/**
* @file lldoubledispatch_tut.cpp
* @author Nat Goodspeed
* @date 2008-11-13
* @brief Test for lldoubledispatch.h
*
* This program tests the DoubleDispatch class, using a variation on the example
* from Scott Meyers' "More Effective C++", Item 31.
*
* $LicenseInfo:firstyear=2008&license=viewergpl$
*
* Copyright (c) 2008-2009, Linden Research, Inc.
*
* Second Life Viewer Source Code
* The source code in this file ("Source Code") is provided by Linden Lab
* to you under the terms of the GNU General Public License, version 2.0
* ("GPL"), unless you have obtained a separate licensing agreement
* ("Other License"), formally executed by you and Linden Lab. Terms of
* the GPL can be found in doc/GPL-license.txt in this distribution, or
* online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
*
* There are special exceptions to the terms and conditions of the GPL as
* it is applied to this Source Code. View the full text of the exception
* in the file doc/FLOSS-exception.txt in this software distribution, or
* online at
* http://secondlifegrid.net/programs/open_source/licensing/flossexception
*
* By copying, modifying or distributing this software, you acknowledge
* that you have read and understood your obligations described above,
* and agree to abide by those obligations.
*
* ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
* WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
* COMPLETENESS OR PERFORMANCE.
* $/LicenseInfo$
*/
// Precompiled header
#include "linden_common.h"
// associated header
#include "lldoubledispatch.h"
// STL headers
// std headers
#include <string>
#include <iostream>
#include <typeinfo>
// external library headers
// other Linden headers
#include "lltut.h"
/*---------------------------- Class hierarchy -----------------------------*/
// All objects are GameObjects.
class GameObject
{
public:
GameObject(const std::string& name): mName(name) {}
virtual ~GameObject() {}
virtual std::string stringize() { return std::string(typeid(*this).name()) + " " + mName; }
protected:
std::string mName;
};
// SpaceStation, Asteroid and SpaceShip are peer GameObjects.
struct SpaceStation: public GameObject
{
SpaceStation(const std::string& name): GameObject(name) {}
// Only a dummy SpaceStation is constructed without a name
SpaceStation(): GameObject("dummy") {}
};
struct Asteroid: public GameObject
{
Asteroid(const std::string& name): GameObject(name) {}
Asteroid(): GameObject("dummy") {}
};
struct SpaceShip: public GameObject
{
SpaceShip(const std::string& name): GameObject(name) {}
SpaceShip(): GameObject("dummy") {}
};
// SpaceShip is specialized further into CommercialShip and MilitaryShip.
struct CommercialShip: public SpaceShip
{
CommercialShip(const std::string& name): SpaceShip(name) {}
CommercialShip(): SpaceShip("dummy") {}
};
struct MilitaryShip: public SpaceShip
{
MilitaryShip(const std::string& name): SpaceShip(name) {}
MilitaryShip(): SpaceShip("dummy") {}
};
/*-------------------------- Collision functions ---------------------------*/
// This mechanism permits us to overcome a limitation of Meyers' approach: we
// can declare the parameter types exactly as we want, rather than having to
// make them all GameObject& parameters.
std::string shipAsteroid(SpaceShip& ship, Asteroid& rock)
{
// std::cout << rock.stringize() << " has pulverized " << ship.stringize() << std::endl;
return "shipAsteroid";
}
std::string militaryShipAsteroid(MilitaryShip& ship, Asteroid& rock)
{
// std::cout << rock.stringize() << " has severely damaged " << ship.stringize() << std::endl;
return "militaryShipAsteroid";
}
std::string shipStation(SpaceShip& ship, SpaceStation& dock)
{
// std::cout << ship.stringize() << " has docked at " << dock.stringize() << std::endl;
return "shipStation";
}
std::string asteroidStation(Asteroid& rock, SpaceStation& dock)
{
// std::cout << rock.stringize() << " has damaged " << dock.stringize() << std::endl;
return "asteroidStation";
}
/*------------------------------- Test code --------------------------------*/
namespace tut
{
struct dispatch_data
{
dispatch_data():
home(new SpaceStation("Terra Station")),
obstacle(new Asteroid("Ganymede")),
tug(new CommercialShip("Pilotfish")),
patrol(new MilitaryShip("Enterprise"))
{}
// Instantiate and populate the DoubleDispatch object.
typedef LLDoubleDispatch<std::string, GameObject> DD;
DD dispatcher;
// Instantiate a few GameObjects. Make sure we refer to them
// polymorphically, and don't let them leak.
std::auto_ptr<GameObject> home;
std::auto_ptr<GameObject> obstacle;
std::auto_ptr<GameObject> tug;
std::auto_ptr<GameObject> patrol;
// prototype objects
Asteroid dummyAsteroid;
SpaceShip dummyShip;
MilitaryShip dummyMilitary;
CommercialShip dummyCommercial;
SpaceStation dummyStation;
};
typedef test_group<dispatch_data> dispatch_group;
typedef dispatch_group::object dispatch_object;
tut::dispatch_group ddgr("double dispatch");
template<> template<>
void dispatch_object::test<1>()
{
// Describe param types using explicit DD::Type objects
// (order-sensitive add() variant)
dispatcher.add(DD::Type<SpaceShip>(), DD::Type<Asteroid>(), shipAsteroid, true);
// naive adding, won't work
dispatcher.add(DD::Type<MilitaryShip>(), DD::Type<Asteroid>(), militaryShipAsteroid, true);
dispatcher.add(DD::Type<SpaceShip>(), DD::Type<SpaceStation>(), shipStation, true);
dispatcher.add(DD::Type<Asteroid>(), DD::Type<SpaceStation>(), asteroidStation, true);
// Try colliding them.
ensure_equals(dispatcher(*home, *tug), // reverse params, SpaceShip subclass
"shipStation");
ensure_equals(dispatcher(*patrol, *home), // forward params, SpaceShip subclass
"shipStation");
ensure_equals(dispatcher(*obstacle, *home), // forward params
"asteroidStation");
ensure_equals(dispatcher(*home, *obstacle), // reverse params
"asteroidStation");
ensure_equals(dispatcher(*tug, *obstacle), // forward params, SpaceShip subclass
"shipAsteroid");
ensure_equals(dispatcher(*obstacle, *patrol), // reverse params, SpaceShip subclass
// won't use militaryShipAsteroid() because it was added
// in wrong order
"shipAsteroid");
}
template<> template<>
void dispatch_object::test<2>()
{
// Describe param types using explicit DD::Type objects
// (order-sensitive add() variant)
// adding in correct order
dispatcher.add(DD::Type<MilitaryShip>(), DD::Type<Asteroid>(), militaryShipAsteroid, true);
dispatcher.add(DD::Type<SpaceShip>(), DD::Type<Asteroid>(), shipAsteroid, true);
dispatcher.add(DD::Type<SpaceShip>(), DD::Type<SpaceStation>(), shipStation, true);
dispatcher.add(DD::Type<Asteroid>(), DD::Type<SpaceStation>(), asteroidStation, true);
ensure_equals(dispatcher(*patrol, *obstacle), "militaryShipAsteroid");
ensure_equals(dispatcher(*tug, *obstacle), "shipAsteroid");
}
template<> template<>
void dispatch_object::test<3>()
{
// Describe param types with actual prototype instances
// (order-insensitive add() variant)
dispatcher.add(dummyMilitary, dummyAsteroid, militaryShipAsteroid);
dispatcher.add(dummyShip, dummyAsteroid, shipAsteroid);
dispatcher.add(dummyShip, dummyStation, shipStation);
dispatcher.add(dummyAsteroid, dummyStation, asteroidStation);
ensure_equals(dispatcher(*patrol, *obstacle), "militaryShipAsteroid");
ensure_equals(dispatcher(*tug, *obstacle), "shipAsteroid");
ensure_equals(dispatcher(*obstacle, *patrol), "");
}
template<> template<>
void dispatch_object::test<4>()
{
// Describe param types with actual prototype instances
// (order-insensitive add() variant)
dispatcher.add(dummyShip, dummyAsteroid, shipAsteroid);
// Even if we add the militaryShipAsteroid in the wrong order, it
// should still work.
dispatcher.add(dummyMilitary, dummyAsteroid, militaryShipAsteroid);
dispatcher.add(dummyShip, dummyStation, shipStation);
dispatcher.add(dummyAsteroid, dummyStation, asteroidStation);
ensure_equals(dispatcher(*patrol, *obstacle), "militaryShipAsteroid");
ensure_equals(dispatcher(*tug, *obstacle), "shipAsteroid");
}
template<> template<>
void dispatch_object::test<5>()
{
dispatcher.add<SpaceShip, Asteroid>(shipAsteroid);
dispatcher.add<MilitaryShip, Asteroid>(militaryShipAsteroid);
dispatcher.add<SpaceShip, SpaceStation>(shipStation);
dispatcher.add<Asteroid, SpaceStation>(asteroidStation);
ensure_equals(dispatcher(*patrol, *obstacle), "militaryShipAsteroid");
ensure_equals(dispatcher(*tug, *obstacle), "shipAsteroid");
}
} // namespace tut
|
