Solution

/*******************************************************
** Name:        arc.h
** Author:      Leo Liberti
** Source:      GNU C++
** Purpose:     www exploring topologizer - arc class (header)
** History:     060820 work started
*******************************************************/

#ifndef _WETARCH
#define _WETARCH

class Arc {
 public:
  Arc(int IDFrom, int IDTo);
  ~Arc();

  int getFrom(void) const;
  int getTo(void) const;

 private:
  int from;
  int to;
};

#endif

/*******************************************************
** Name:        arc.cxx
** Author:      Leo Liberti
** Source:      GNU C++
** Purpose:     www exploring topologizer - arc class 
** History:     060820 work started
*******************************************************/

#include "arc.h"

Arc::Arc(int fromID, int toID) : from(fromID), to(toID) { }
Arc::~Arc() { }

int Arc::getFrom(void) const {
  return from;
}

int Arc::getTo(void) const {
  return to;
}

/*******************************************************
** Name:        digraph.h
** Author:      Leo Liberti
** Source:      GNU C++
** Purpose:     www exploring topologizer - digraph class (header)
** History:     060820 work started
*******************************************************/

#ifndef _WETDIGRAPHH
#define _WETDIGRAPHH

#include<vector>
#include "vertex.h"
#include "vertexurl.h"
#include "arc.h"
#include "timestamp.h"

class DigraphException {
 public:
  DigraphException();
  ~DigraphException();
};

class Digraph {
 public:
  Digraph();
  ~Digraph();
  
  void setTimeStamp(TimeStamp& ts);
  TimeStamp& getTimeStamp(void);
  int getNumberOfVertices(void) const;
  int getNumberOfArcs(void) const;
  void addVertex(Vertex& theVertex);
  void addArc(Arc& theArc);
  Vertex& getVertex(int i) throw(DigraphException);
  Arc& getArc(int i) throw(DigraphException);
  
 private:
  std::vector<Vertex*> vertexPtr;
  std::vector<Arc*> arcPtr;
  TimeStamp ts;

};

std::ostream& operator<< (std::ostream& out, Digraph& G);

#endif

/*******************************************************
** Name:        digraph.cxx
** Author:      Leo Liberti
** Source:      GNU C++
** Purpose:     www exploring topologizer - digraph class
** History:     060820 work started
*******************************************************/

#include<iostream>
#include "digraph.h"

DigraphException::DigraphException() { }
DigraphException::~DigraphException() { }

Digraph::Digraph() { }
Digraph::~Digraph() { 
  using namespace std;
  // delete vertices and arcs
  for(vector<Vertex*>::iterator vi = vertexPtr.begin(); 
      vi != vertexPtr.end(); vi++) {
    delete *vi;
  }
  for(vector<Arc*>::iterator vi = arcPtr.begin(); vi != arcPtr.end(); vi++) {
    delete *vi;
  }
#ifdef DEBUG
  std::cerr << "** destroying Digraph " << this << std::endl; 
#endif
}

int Digraph::getNumberOfVertices(void) const {
  return vertexPtr.size();
}

int Digraph::getNumberOfArcs(void) const {
  return arcPtr.size();
}

void Digraph::addVertex(Vertex& theVertex) {
  vertexPtr.push_back(&theVertex);
}

void Digraph::addArc(Arc& theArc) {
  arcPtr.push_back(&theArc);
}

Vertex& Digraph::getVertex(int i) throw(DigraphException) {
  using namespace std;
  if (i < 0 || i >= vertexPtr.size()) {
    cerr << "Digraph::getVertex(" << i << "): index out of bounds" << endl;
    throw DigraphException();
  }
  return *vertexPtr[i];
}

Arc& Digraph::getArc(int i) throw(DigraphException) {
  using namespace std;
  if (i < 0 || i >= arcPtr.size()) {
    cerr << "Digraph::getArc(" << i << "): index out of bounds" << endl;
    throw DigraphException();
  }
  return *arcPtr[i];
}

void Digraph::setTimeStamp(TimeStamp& theTs) {
  ts = theTs;
}

TimeStamp& Digraph::getTimeStamp(void) {
  return ts;
}

std::ostream& operator<< (std::ostream& out, Digraph& G) {
  using namespace std;
  out << "# graphviz output by WET (L. Liberti 2006)" << endl;
  out << "digraph www_" << G.getTimeStamp().get() << " {" << endl;
  int n = G.getNumberOfVertices();
  for(int i = 0; i < n; i++) {
    Vertex& v = G.getVertex(i);
    VertexURL* vptr = dynamic_cast<VertexURL*>(&v);
    out << "  " << i << " [ label = \"" << G.getVertex(i).getText()
	<< "\" ];" << endl;
  }
  out << "  " << n << " [ label = \"" << G.getTimeStamp() 
      << "\", color = red ];" << endl;
  int m = G.getNumberOfArcs();
  int from, to;
  for(int i = 0; i < m; i++) {
    from = G.getArc(i).getFrom();
    to = G.getArc(i).getTo();
    out << "   " << from << " -> " << to << ";" << endl;
  }
  out << "}" << endl;
}