wires.h

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#ifndef _WIRES_H
#define _WIRES_H

#include <iostream>
#include <string>
using namespace std;
#include "tvector.h"

// A wire has current flowing through it.
// When the current changes, a wire notifies
// all the gates listening on the wire that the current
// has changed.  The gates act accordingly (see gates.h).
//
// Some of the "gates" are really connectors to other wires.
// A connector allows gates to be strung together, but connectors
// are more like solder than real gates.  As such, connectors aren't
// part of a CompositeGate.  To facilitate finding a wire's
// connectors, a ConnectorIterator can be used to access all a wire's
// connectors.

class Gate;
class Connector;

class Wire
{
  public:
    Wire(const string& name="");
    virtual ~Wire(); 
    virtual bool   GetSignal() const;       // true/false, on/off
    virtual string tostring()  const;       // for I/O
    
    virtual void   SetSignal(bool signal);  // set signal, propagate
    virtual void   AddGate(Gate * g);       // g monitors this wire
    virtual void   RemoveGate(Gate * g);    // g stops monitoring
    virtual int    Number() const;          // which wire is this?
    
    friend class ConnectorIterator;         // access myGates
    
  private:
  
    tvector<Gate *>      myGates;
    bool                 mySignal;
    string               myName;
    int                  myNumber;
    static int           ourCount;           // class wide, keeps count
};

ostream& operator << (ostream& out, const Wire& w);

// A WireFactory is used to encapsulate wire creation.
// If wires are "ordered" from the factory, the factory takes
// care of cleaning up the wires when the factory ceases to exist.
// This is a rudimentary factory, there's no facility for clients
// to recycle wires and the factory doesn't clean up the gates
// attached to the wires it destroys.
//
// MakeWire -- creates a new wire
// GetWire  -- retrieves an already created wire by the wire's number

class WireFactory
{
  public:
    WireFactory();
    virtual ~WireFactory();
    virtual Wire * MakeWire(const string& name="wire"); // create anew
    virtual Wire * GetWire(int num) const;              // get by number
  private:
    tvector<Wire *> myWires;
};

// standard tapestry iterator for iterating over all
// connectors attached to a wire

class ConnectorIterator
{
  public:
    ConnectorIterator(Wire* w);
    void Init();
    bool HasMore();
    void Next();
    Connector * Current();
  private:
    Wire *      myWire;
    Connector * myConnector;
    int         myIndex;
};

#endif