命令模式实现撤销和重做机制

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#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; }