composite.c

《设计模式－可复用面向对象软件的基础》的经典模式源码实例

/*
*/
class Composite;

class Component {
public:
    //...
    virtual Composite* GetComposite() { return 0; }
};
/*
*/
class Composite : public Component {
public:
    void Add(Component*);
    // ...
    virtual Composite* GetComposite() { return this; }
};
/*
*/
class Leaf : public Component {
    // ...
};
/*
*/
void dummy () {
/*
*/
Composite* aComposite = new Composite;
Leaf* aLeaf = new Leaf;

Component* aComponent;
Composite* test;
/*
*/
aComponent = aComposite;
if (test = aComponent->GetComposite()) {
    test->Add(new Leaf);
}
/*
*/
aComponent = aLeaf;

if (test = aComponent->GetComposite()) {
    test->Add(new Leaf); // will not add leaf
}
/*
*/
}
/*
*/
#include "List.H"
#include "iostream.h"
typedef int Watt;
typedef int Currency;
typedef int Power;
/*
*/
class Equipment {
public:
    virtual ~Equipment();

    const char* Name() { return _name; }
/*
*/
    virtual Watt Power();
    virtual Currency NetPrice();
    virtual Currency DiscountPrice();
/*
*/
    virtual void Add(Equipment*);
    virtual void Remove(Equipment*);
    virtual Iterator<Equipment*>* CreateIterator();
protected:
    Equipment(const char*);
private:
    const char* _name;
};
/*
*/
class FloppyDisk : public Equipment {
public:
    FloppyDisk(const char*);
    virtual ~FloppyDisk();
/*
*/
    virtual Watt Power();
    virtual Currency NetPrice();
    virtual Currency DiscountPrice();
};
/*
*/
class CompositeEquipment : public Equipment {
public:
    virtual ~CompositeEquipment();
/*
*/
    virtual Watt Power();
    virtual Currency NetPrice();
    virtual Currency DiscountPrice();
/*
*/
    virtual void Add(Equipment*);
    virtual void Remove(Equipment*);
    virtual Iterator<Equipment*>* CreateIterator();
/*
*/
protected:
    CompositeEquipment(const char*);
private:
    List<Equipment*> _equipment;
};
/*
*/
Currency CompositeEquipment::NetPrice () {
    Iterator<Equipment*>* i = CreateIterator();
    Currency total = 0;

    for (i->First(); !i->IsDone(); i->Next()) {
        total += i->CurrentItem()->NetPrice();
    }
    delete i;
    return total;
}
/*
*/
class Chassis : public CompositeEquipment {
public:
    Chassis(const char*);
    virtual ~Chassis();
/*
*/
    virtual Watt Power();
    virtual Currency NetPrice();
    virtual Currency DiscountPrice();
};
/*
*/
class Cabinet  : public CompositeEquipment {
public:
    Cabinet(const char*);
};
class Bus  : public CompositeEquipment {
public:
    Bus(const char*);
};
class Card  : public Equipment {
public:
    Card(const char*);
};
void dummy1 () {
/*
*/
Cabinet* cabinet = new Cabinet("PC Cabinet");
Chassis* chassis = new Chassis("PC Chassis");
/*
*/
cabinet->Add(chassis);
/*
*/
Bus* bus = new Bus("MCA Bus");
bus->Add(new Card("16Mbs Token Ring"));
/*
*/
chassis->Add(bus);
chassis->Add(new FloppyDisk("3.5in Floppy"));

cout << "The net price is " << chassis->NetPrice() << endl;
/*
*/
}
/*
*/