command模式(c 語言實現)

command 模式：把“做菜的廚師”和“一道菜的名字”封裝起來，對外看起來就是“一道菜的名字”。然後“這道菜”就可以“被寫在菜單上”，供顧客點餐。

下面是c語言的實現代碼：

#include <stdio.h>
#include <stdlib.h>


//命令接口
struct command_interface
{
	int (*on)(void);
	int (*off)(void);
};



typedef int (*plight_method)(void);
typedef int (*pcd_method)(void);
//light 
struct light
{
	int light_big;
	int (*light_on)(void);
	int (*light_off)(void);
	int (*init)(plight_method on_method, plight_method off_method, struct light *plight);
};

int my_light_on(void)
{
	printf("my_light_on\n");
	return 0;
}

int my_light_off(void)
{
	printf("my_light_off\n");
	return 0;
}

int light_init(plight_method on_method, plight_method off_method, struct light *plight)
{
	plight->light_on = on_method;
	plight->light_off = off_method;
	return 0;
}
struct light_command
{
	struct command_interface *pbase_interface;
	struct light *plight_instance;
	int (*init)(struct light *plight, struct light_command *plight_command);
};


int light_command_init(struct light *plight, struct light_command *plight_command)
{
	plight_command->plight_instance = plight;
	struct command_interface *my_command = (struct command_interface *)(&(plight_command->pbase_interface));
	my_command->on = plight_command->plight_instance->light_on;
	my_command->off = plight_command->plight_instance->light_off;
	return 0;
}


//CD
struct cd
{
	int cd_big;
	int (*cd_on)(void);
	int (*cd_off)(void);
	int (*init)(pcd_method on_method, pcd_method off_method, struct cd *pcd);
};

int my_cd_on(void)
{
	printf("my_cd_on\n");
	return 0;
}

int my_cd_off(void)
{
	printf("my_cd_off\n");
	return 0;
}

int cd_init(pcd_method on_method, pcd_method off_method, struct cd *pcd)
{
	pcd->cd_on = on_method;
	pcd->cd_off = off_method;
	return 0;
}
struct cd_command
{
	struct command_interface *pbase_interface;
	struct cd *pcd_instance;
	int (*init)(struct cd *pcd, struct cd_command *pcd_command);
};


int cd_command_init(struct cd *pcd, struct cd_command *pcd_command)
{
	pcd_command->pcd_instance = pcd;
	struct command_interface *my_command = (struct command_interface *)(&(pcd_command->pbase_interface));
	my_command->on = pcd_command->pcd_instance->cd_on;
	my_command->off = pcd_command->pcd_instance->cd_off;
	return 0;
}

//命令控制器
struct command_controller
{
	struct command_interface * command_pointer_slot[2];
	int (*set_command_slot)(struct command_interface * command_pointer, int slot, struct command_controller *pcommand_controller);
};

int set_command_slot(struct command_interface * command_pointer, int slot, struct command_controller *pcommand_controller)
{
	pcommand_controller->command_pointer_slot[slot] = command_pointer;
	return 0;
}
int main()
{
	printf("hello world.\n");

	//light命令初始化
	struct light my_light = {0};
	my_light.init = light_init;
	my_light.init(my_light_on, my_light_off, &my_light);


	struct light_command my_light_command = {0};
	my_light_command.init = light_command_init;
	my_light_command.init(&my_light, &my_light_command);

	//cd命令初始化
	struct cd my_cd = {0};
	my_cd.init = cd_init;
	my_cd.init(my_cd_on, my_cd_off, &my_cd);

	struct cd_command my_cd_command = {0};
	my_cd_command.init = cd_command_init;
	my_cd_command.init(&my_cd, &my_cd_command);

	//將兩個命令安裝到控制器中
	struct command_controller my_command_controller = {0};
	my_command_controller.set_command_slot = set_command_slot;
	my_command_controller.set_command_slot((struct command_interface *)(&my_light_command), 0, &my_command_controller);
	my_command_controller.set_command_slot((struct command_interface *)(&my_cd_command), 1, &my_command_controller);

	//控制器不用關心被設置了什麼命令，卻可以正常的調用接口執行命令。可以動態的設置不同類型的命令到控制器中。
	for (int i = 0; i < 2; i++)
	{
		struct command_interface *user_command = my_command_controller.command_pointer_slot[i];
		user_command->on();
		user_command->off();
	}
	getchar();
}