组合模式

#include <iostream>
#include <string>
#include <vector>
#include <sstream>

using namespace std;


struct MenuComponent {
    virtual add(MenuComponent *menuComponent) {}
    virtual remove(MenuComponent *menuComponent) {}
    virtual MenuComponent *getChild(int i) {return NULL;}
    virtual string getName() {return "";}
    virtual string getDescription() {return "";}
    virtual double getPrice() {return 0.0;}
    virtual bool isVegetarian() {return false;}
    virtual print() {}
};

struct MenuItem : public MenuComponent {
    string name;
    string description;
    bool vegetarian;
    double price;

    MenuItem(string name,
             string description,
             bool vegetarian,
             double price)
    {
        this->name = name;
        this->description = description;
        this->vegetarian = vegetarian;
        this->price = price;
    }

    virtual string getName() {
        return name;
    }

    virtual string getDescription() {
        return description;
    }

    virtual double getPrice() {
        return price;
    }

    virtual bool isVegetarian() {
        return vegetarian;
    }
    virtual print() {
        cout << " " << getName();
        if (isVegetarian()) {
            cout << "(V)";
        }
        cout << ", " << getPrice();
        cout << "    -- " << getDescription() << endl;
    }
};

struct Menu : public MenuComponent {
    vector<MenuComponent *> menuComponents;
    string name;
    string description;

    Menu(string name, string description) {
        this->name = name;
        this->description = description;
    }
    virtual add(MenuComponent *menuComponent) {
        menuComponents.push_back(menuComponent);
    }
    virtual remove(MenuComponent menuComponent) {
        //menuComponents.remove(menuComponent);
    }
    virtual MenuComponent *getChild(int i) {
        return menuComponents[i];
    }
    virtual string getName() {
        return name;
    }
    virtual string getDescription() {
        return description;
    }
    virtual print() {
        cout << "\n" << getName();
        cout << ", " << getDescription() << endl;
        cout << "-------------------------" << endl;

        vector<MenuComponent *>::iterator it;
        for (it = menuComponents.begin(); it != menuComponents.end(); ++it) {
            (*it)->print();
        }
    }
};

struct Waitress {
public:
    Waitress(MenuComponent *allMenus) {
        this->allMenus = allMenus;
    }

    printMenu() {
        allMenus->print();
    }
private:
    MenuComponent *allMenus;
};

int main(int argc, char **argv)
{
    MenuComponent *pancakeHouseMenu =
        new Menu("PANCAKE HOUSE MENU", "Breakfast");
    MenuComponent *dinerMenu =
        new Menu("DINER MENU", "Lunch");
    MenuComponent *cafeMenu =
        new Menu("CAFE MENU", "Dinner");
    MenuComponent *dessertMenu =
        new Menu("DESSERT MENU", "Dessert of course!");

    MenuComponent *allMenus = new Menu("ALL MENUS", "All menus combined");

    allMenus->add(pancakeHouseMenu);
    allMenus->add(dinerMenu);
    allMenus->add(cafeMenu);

    pancakeHouseMenu->add(new MenuItem(
        "K&B's Pancake Breakfast",
        "Pancakes with scrambled eggs, and toast",
        true,
        2.99));

    pancakeHouseMenu->add(new MenuItem(
        "Regular Pancake Breakfast",
        "Pancakes with fried eggs, sausage",
        false,
        2.99));

    pancakeHouseMenu->add(new MenuItem(
        "Blueberry Pancakes",
        "Pancakes made with fresh blueberries",
        true,
        3.49));

    pancakeHouseMenu->add(new MenuItem(
        "Waffles",
        "Waffles, with your choice of blueberries or strawberries",
        true,
        3.59));

    dinerMenu->add(new MenuItem(
        "Vegetarian BLT",
        "(Fakin') Bacon with lettuce & tomato on whole wheat",
        true,
        2.99));
    dinerMenu->add(new MenuItem(
        "BLT",
        "Bacon with lettuce & tomato on whole wheat",
        false,
        2.99));
    dinerMenu->add(new MenuItem(
        "Soup of the day",
        "Soup of the day, with a side of potato salad",
        false,
        3.29));
    dinerMenu->add(new MenuItem(
        "Hotdog",
        "A hot dog, with saurkraut, relish, onions, topped with cheese",
        false,
        3.05));
    dinerMenu->add(new MenuItem(
        "Steamed Veggies and Brown Rice",
        "Steamed vegetables over brown rice",
        true,
        3.99));
    dinerMenu->add(new MenuItem(
        "Pasta",
        "Spaghetti with Marinara Sauce, and a slice of sourdough bread",
        true,
        3.89));

    dinerMenu->add(dessertMenu);

    dessertMenu->add(new MenuItem(
        "Apple Pie",
        "Apple pie with a flakey crust, topped with vanilla ice cream",
        true,
        1.59));

    Waitress *waitress = new Waitress(allMenus);

    waitress->printMenu();
}