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lldoubledispatch_tut.cpp 8.86 KiB
/**
* @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.
*
* $LicenseInfo:firstyear=2008&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2010, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
// 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::unique_ptr<GameObject> home;
std::unique_ptr<GameObject> obstacle;
std::unique_ptr<GameObject> tug; std::unique_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