命令模式实现撤销和重做机制

#include <vector>
#include <iostream>

//定义命令接口
class Command 
{
public:
	virtual void execute() = 0;
	virtual void undo() = 0;
};

//实现“增加”命令类
class IncreaseCommand : public Command 
{
private:
	int* _value;
	int _amount;
public:
	IncreaseCommand(int* value, int amount) : _value(value), _amount(amount) 
	{

	}

	void execute() override 
	{
		*_value += _amount; 
	}
	
	void undo() override 
	{ 
		*_value -= _amount; 
	}
};

//实现“减少”命令类
class DecreaseCommand : public Command 
{
private:
	int* _value;
	int _amount;
public:
	DecreaseCommand(int* value, int amount) : _value(value), _amount(amount) 
	{

	}

	void execute() override 
	{
		*_value -= _amount; 
	}

	void undo() override 
	{
		*_value += _amount; 
	}
};

//实现命令管理器
class CommandManager 
{
private:
	std::vector<Command*> _executedCommands;
	std::vector<Command*> _undoneCommands;
public:
	CommandManager() {}
	~CommandManager()
	{
		for (auto& cmd : _executedCommands)
		{
			delete cmd;
		}

		for (auto& cmd : _undoneCommands)
		{
			delete cmd;
		}
	}

	void execute(Command* command) 
	{
		command->execute();
		_executedCommands.push_back(command);
		_undoneCommands.clear(); // 清除重做命令列表
	}

	void undo() 
	{
		if (!_executedCommands.empty()) 
		{
			Command* lastCommand = _executedCommands.back();
			lastCommand->undo();
			_undoneCommands.push_back(lastCommand);
			_executedCommands.pop_back();
		}
	}

	void redo() 
	{
		if (!_undoneCommands.empty()) 
		{
			Command* lastCommand = _undoneCommands.back();
			lastCommand->execute();
			_executedCommands.push_back(lastCommand);
			_undoneCommands.pop_back();
		}
	}
};


int main()
{
	int value = 10;
	CommandManager manager;

	// 增加 5
	manager.execute(new IncreaseCommand(&value, 5));
	std::cout << "Value: " << value << std::endl; // 输出: 15

	// 减少 3
	manager.execute(new DecreaseCommand(&value, 3));
	std::cout << "Value: " << value << std::endl; // 输出: 12

	// 撤销
	manager.undo();
	std::cout << "Value: " << value << std::endl; // 输出: 15

	// 重做
	manager.redo();
	std::cout << "Value: " << value << std::endl; // 输出: 12

	return 0;
}