/**/class Memento;/**/class State;class Originator {public:    Memento* CreateMemento();    void SetMemento(const Memento*);    // ...private:    State* _state;      // internal data structures    // ...};/**/class Memento {public:    // narrow public interface    virtual ~Memento();private:    // private members accessible only to Originator    friend class Originator;    Memento();/**/    void SetState(State*);    State* GetState();    // ...private:    State* _state;    // ...};/**/#include "Geom.H"class ConstraintSolverMemento;class ConstraintSolver;class Graphic {  public:   void  Move(const Point&);};/**/class Graphic;    // base class for graphical objects in the graphical editorclass MoveCommand {public:    MoveCommand(Graphic* target, const Point& delta);    void Execute();    void Unexecute();private:    ConstraintSolverMemento* _state;    Point _delta;    Graphic* _target;};/**/class ConstraintSolver {public:    static ConstraintSolver* Instance();/**/    void Solve();    void AddConstraint(        Graphic* startConnection, Graphic* endConnection    );    void RemoveConstraint(        Graphic* startConnection, Graphic* endConnection    );/**/    ConstraintSolverMemento* CreateMemento();    void SetMemento(ConstraintSolverMemento*);private:    // nontrivial state and operations for enforcing    // connectivity semantics};/**/class ConstraintSolverMemento {public:    virtual ~ConstraintSolverMemento();private:    friend class ConstraintSolver;    ConstraintSolverMemento();    // private constraint solver state};/**/void MoveCommand::Execute () {    ConstraintSolver* solver = ConstraintSolver::Instance();    _state = solver->CreateMemento(); // create a memento    _target->Move(_delta);    solver->Solve();}/**/void MoveCommand::Unexecute () {    ConstraintSolver* solver = ConstraintSolver::Instance();    _target->Move(-_delta);    solver->SetMemento(_state); // restore solver state    solver->Solve();}/**/class IterationState;/**/template <class Item>class Collection {public:    Collection();    IterationState* CreateInitialState();    void Next(IterationState*);    bool IsDone(const IterationState*) const;    Item CurrentItem(const IterationState*) const;    IterationState* Copy(const IterationState*) const;    void Append(const Item&);    void Remove(const Item&);    // ...};/**/class ItemType {public:    void Process();    // ...};/**/class IterationState {};void dummy () {/**/Collection<ItemType*> aCollection;IterationState* state;state = aCollection.CreateInitialState();while (!aCollection.IsDone(state)) {    aCollection.CurrentItem(state)->Process();    aCollection.Next(state);}delete state;/**/}/**/