/**/// Copilation Instructions// #define Implementation | Consequences | SampleCode#include "Foundation.H"#include <iostream.h>/**/#ifdef Consequences/**/#ifndef Foundation_H/**/template <class Item>class Iterator {    // ...    Item CurrentItem() const;};/**/#endif/**/class MyType;class YourType;/**/class Visitor {public:    // ...    void VisitMyType(MyType*);    void VisitYourType(YourType*);};/**/#endif/**/#ifdef Implementationclass ElementA;class ElementB;/**/class Visitor {public:    virtual void VisitElementA(ElementA*);    virtual void VisitElementB(ElementB*);    // and so on for other concrete elementsprotected:    Visitor();};/**/class Element {public:    virtual ~Element();    virtual void Accept(Visitor&) = 0;protected:    Element();};/**/class ElementA : public Element {public:    ElementA();    virtual void Accept(Visitor& v) { v.VisitElementA(this); }};/**/class ElementB : public Element {public:    ElementB();    virtual void Accept(Visitor& v) { v.VisitElementB(this); }};/**/class CompositeElement : public Element {public:    virtual void Accept(Visitor&);private:    List<Element*>* _children;};/**/void CompositeElement::Accept (Visitor& v) {    ListIterator<Element*> i(_children);    for (i.First(); !i.IsDone(); i.Next()) {        i.CurrentItem()->Accept(v);    }    v.VisitCompositeElement(this);}/**/#endif Implementation/**/#ifdef SampleCodetypedef int Watt;typedef int Currency;typedef int Power;class EquipmentVisitor;class Equipment;class Card;class Bus;class Chassis;class FloppyDisk;class Inventory {  public:    void Accumulate(Equipment*);};/**/class Equipment {public:    virtual ~Equipment();    const char* Name() { return _name; }/**/    virtual Watt Power();    virtual Currency NetPrice();    virtual Currency DiscountPrice();/**/    virtual void Accept(EquipmentVisitor&);protected:    Equipment(const char*);private:    const char* _name;};/**/class EquipmentVisitor {public:    virtual ~EquipmentVisitor();    virtual void VisitFloppyDisk(FloppyDisk*);    virtual void VisitCard(Card*);    virtual void VisitChassis(Chassis*);    virtual void VisitBus(Bus*);    // and so on for other concrete subclasses of Equipmentprotected:    EquipmentVisitor();};/**/class FloppyDisk : public Equipment {  public:    virtual void Accept(EquipmentVisitor&);};/**/void FloppyDisk::Accept (EquipmentVisitor& visitor) {   visitor.VisitFloppyDisk(this);}/**/class CompositeEquipment : public Equipment {  public:    virtual void Accept(EquipmentVisitor&);};class Chassis : public CompositeEquipment {  public:    virtual void Accept(EquipmentVisitor&);    List<Equipment*>* _parts;};/**/void Chassis::Accept (EquipmentVisitor& visitor) {    for (        ListIterator<Equipment*> i(_parts);        !i.IsDone();        i.Next()    ) {        i.CurrentItem()->Accept(visitor);    }    visitor.VisitChassis(this);}/**/class PricingVisitor : public EquipmentVisitor {public:    PricingVisitor();    Currency& GetTotalPrice();/**/    virtual void VisitFloppyDisk(FloppyDisk*);    virtual void VisitCard(Card*);    virtual void VisitChassis(Chassis*);    virtual void VisitBus(Bus*);    // ...private:    Currency _total;};/**/void PricingVisitor::VisitFloppyDisk (FloppyDisk* e) {    _total += e->NetPrice();}/**/void PricingVisitor::VisitChassis (Chassis* e) {    _total += e->DiscountPrice();}/**/class InventoryVisitor : public EquipmentVisitor {public:    InventoryVisitor();    Inventory& GetInventory();/**/    virtual void VisitFloppyDisk(FloppyDisk*);    virtual void VisitCard(Card*);    virtual void VisitChassis(Chassis*);    virtual void VisitBus(Bus*);    // .../**/private:    Inventory _inventory;};/**/void InventoryVisitor::VisitFloppyDisk (FloppyDisk* e) {    _inventory.Accumulate(e);}/**/void InventoryVisitor::VisitChassis (Chassis* e) {    _inventory.Accumulate(e);}/**/ostream&  operator<<(ostream&, const Inventory&);void dummy() {/**/Equipment* component;InventoryVisitor visitor;component->Accept(visitor);cout << "Inventory "     << component->Name()     << visitor.GetInventory();/**/}/**/#endif/**/