Made iterator inherit from standard library iterator

SpMat.h

@@ -89,39 +89,6 @@ template<class T>
 class SpMat
 {
 public:
-
-    class Iterator {
-    public:
-    Iterator(SpMat<T>& mat, bool oob=false) : _mat(mat), _i(0), _oob(oob)
-      {
-	_j = 0;
-	while (_j < _mat._n && !_mat._ri[_j].size()) _j++;
-	if (_j == _mat._n) _oob = true;
-      }
-      ~Iterator() {}
-      bool operator==(const Iterator& other) { return(&_mat==&other._mat && ((_oob && other._oob) || (_i==other._i && _j==other._j))); }
-      bool operator!=(const Iterator& other) { return(!(*this==other)); }
-      T& operator*() { return((_mat._val[_j])[_i]); }
-      Iterator& operator++() 
-      {
-	if (++_i < _mat._ri[_j].size()) return(*this);
-        else {
-          while (++_j < _mat._n && !_mat._ri[_j].size()) ;
-        }
-        if (_j == _mat._n) _oob = true;
-        else _i = 0;
-        return(*this); 
-      }
-      unsigned int Row() { return((_mat._ri[_j])[_i]+1); }
-      unsigned int Col() { return(_j+1); }
-    private:
-      SpMat<T>&     _mat;
-      unsigned int  _i;
-      unsigned int  _j;
-      bool          _oob;
-    };
-
-
   SpMat() : _m(0), _n(0), _nz(0), _ri(0), _val(0), _pw(false), _ei(*this,true) {}
   SpMat(unsigned int m, unsigned int n) : _m(m), _n(n), _nz(0), _ri(n), _val(n), _pw(false), _ei(*this,true) {}
   SpMat(unsigned int m, unsigned int n, const unsigned int *irp, const unsigned int *jcp, const double *sp);
@@ -133,9 +100,6 @@ public:
   unsigned int Ncols() const {return(_n);}
   unsigned int NZ() const {return(_nz);}
 
-  Iterator         begin() { return(Iterator(*this)); }
-  const Iterator&  end() { return(_ei); }
-
   NEWMAT::ReturnMatrix AsNEWMAT() const;
   void Save(const std::string&   fname,
             unsigned int         precision) const;
@@ -205,6 +169,42 @@ public:
 				 boost::shared_ptr<Preconditioner<T> >  C,
 				 const NEWMAT::ColumnVector&            x_init) const;
 
+  // Declaration and definition of bundled Iterator class
+
+  class Iterator : public std::iterator<std::forward_iterator_tag, T> {
+  public:
+    Iterator(SpMat<T>& mat, bool oob=false) : _mat(mat), _i(0), _oob(oob)
+    {
+      _j = 0;
+      while (_j < _mat._n && !_mat._ri[_j].size()) _j++;
+      if (_j == _mat._n) _oob = true;
+    }
+    ~Iterator() {}
+    bool operator==(const Iterator& other) { return(&_mat==&other._mat && ((_oob && other._oob) || (_i==other._i && _j==other._j))); }
+    bool operator!=(const Iterator& other) { return(!(*this==other)); }
+    T& operator*() { return((_mat._val[_j])[_i]); }
+    Iterator& operator++() 
+    {
+      if (++_i < _mat._ri[_j].size()) return(*this);
+      else {
+        while (++_j < _mat._n && !_mat._ri[_j].size()) ;
+      }
+      if (_j == _mat._n) _oob = true;
+      else _i = 0;
+      return(*this); 
+    }
+    unsigned int Row() { return((_mat._ri[_j])[_i]+1); }
+    unsigned int Col() { return(_j+1); }
+  private:
+    SpMat<T>&     _mat;
+    unsigned int  _i;
+    unsigned int  _j;
+    bool          _oob;
+  };
+
+  Iterator         begin() { return(Iterator(*this)); }
+  const Iterator&  end() { return(_ei); }
+
 private:
   unsigned int                              _m;
   unsigned int                              _n;