//

// command.h

// cpp

//

// Created by Bob Nystrom on 10/7/13.

// Copyright (c) 2013 Bob Nystrom. All rights reserved.

//

#ifndef cpp_command_h

#define cpp_command_h

namespace CommandPattern

{

enum Button

{

BUTTON_UP,

BUTTON_DOWN,

BUTTON_LEFT,

BUTTON_RIGHT,

BUTTON_X,

BUTTON_Y,

BUTTON_A,

BUTTON_B

};

bool isPressed(Button button) { return false; }

void jump() {}

void fireGun() {}

void swapWeapon() {}

void lurchIneffectively() {}

namespace BeforeCommand

{

class InputHandler

{

public:

void handleInput();

};

//^handle-input

void InputHandler::handleInput()

{

if (isPressed(BUTTON_X)) jump();

else if (isPressed(BUTTON_Y)) fireGun();

else if (isPressed(BUTTON_A)) swapWeapon();

else if (isPressed(BUTTON_B)) lurchIneffectively();

}

//^handle-input

}

namespace InputHandlingCommand

{

//^command

class Command

{

public:

virtual ~Command() {}

virtual void execute() = 0;

};

//^command

//^command-classes

class JumpCommand : public Command

{

public:

virtual void execute() { jump(); }

};

class FireCommand : public Command

{

public:

virtual void execute() { fireGun(); }

};

// 你知道思路了吧

//^command-classes

//^input-handler-class

class InputHandler

{

public:

void handleInput();

// 绑定命令的方法……

private:

Command* buttonX_;

Command* buttonY_;

Command* buttonA_;

Command* buttonB_;

};

//^input-handler-class

//^handle-input-commands

void InputHandler::handleInput()

{

if (isPressed(BUTTON_X)) buttonX_->execute();

else if (isPressed(BUTTON_Y)) buttonY_->execute();

else if (isPressed(BUTTON_A)) buttonA_->execute();

else if (isPressed(BUTTON_B)) buttonB_->execute();

}

//^handle-input-commands

}

namespace CommandedActors

{

class GameActor

{

public:

void jump() {}

};

//^actor-command

class Command

{

public:

virtual ~Command() {}

virtual void execute(GameActor& actor) = 0;

};

//^actor-command

//^jump-actor

class JumpCommand : public Command

{

public:

virtual void execute(GameActor& actor)

{

actor.jump();

}

};

//^jump-actor

class InputHandler

{

public:

Command* handleInput();

private:

Command* buttonX_;

Command* buttonY_;

Command* buttonA_;

Command* buttonB_;

};

//^handle-input-return

Command* InputHandler::handleInput()

{

if (isPressed(BUTTON_X)) return buttonX_;

if (isPressed(BUTTON_Y)) return buttonY_;

if (isPressed(BUTTON_A)) return buttonA_;

if (isPressed(BUTTON_B)) return buttonB_;

// 没有按下任何按键，就什么也不做

return NULL;

}

//^handle-input-return

void executeCommand()

{

InputHandler inputHandler;

GameActor actor;

//^call-actor-command

Command* command = inputHandler.handleInput();

if (command)

{

command->execute(actor);

}

//^call-actor-command

use(actor);

}

}

namespace Undo

{

class Unit {

public:

int x() { return 0; }

int y() { return 0; }

void moveTo(int x, int y) {}

};

namespace UndoBefore

{

class Command

{

public:

virtual ~Command() {}

virtual void execute() = 0;

};

//^move-unit

class MoveUnitCommand : public Command

{

public:

MoveUnitCommand(Unit* unit, int x, int y)

: unit_(unit),

x_(x),

y_(y)

{}

virtual void execute()

{

unit_->moveTo(x_, y_);

}

private:

Unit* unit_;

int x_, y_;

};

//^move-unit

Unit* getSelectedUnit() { return NULL; }

//^get-move

Command* handleInput()

{

Unit* unit = getSelectedUnit();

if (isPressed(BUTTON_UP)) {

// 向上移动单位

int destY = unit->y() - 1;

return new MoveUnitCommand(unit, unit->x(), destY);

}

if (isPressed(BUTTON_DOWN)) {

// 向下移动单位

int destY = unit->y() + 1;

return new MoveUnitCommand(unit, unit->x(), destY);

}

// 其他的移动……

return NULL;

}

//^get-move

}

namespace UndoAfter

{

//^undo-command

class Command

{

public:

virtual ~Command() {}

virtual void execute() = 0;

virtual void undo() = 0;

};

//^undo-command

//^undo-move-unit

class MoveUnitCommand : public Command

{

public:

MoveUnitCommand(Unit* unit, int x, int y)

: unit_(unit),

xBefore_(0),

yBefore_(0),

x_(x),

y_(y)

{}

virtual void execute()

{

// 保存移动之前的位置

// 这样之后可以复原。

xBefore_ = unit_->x();

yBefore_ = unit_->y();

unit_->moveTo(x_, y_);

}

virtual void undo()

{

unit_->moveTo(xBefore_, yBefore_);

}

private:

Unit* unit_;

int xBefore_, yBefore_;

int x_, y_;

};

//^undo-move-unit

}

}

}

#endif