From 34a7988a36fa27f272a913ea20bb658b3b04392b Mon Sep 17 00:00:00 2001
From: wolf <wolf@0785d39b-7218-0410-832d-ea1e28bc413d>
Date: Fri, 30 Nov 2001 13:06:54 +0000
Subject: [PATCH] Move the IteratorState to a namespace of its own, to move it
 out of the global namespace.

git-svn-id: https://svn.dealii.org/trunk@5318 0785d39b-7218-0410-832d-ea1e28bc413d
---
 .../include/dofs/dof_accessor.templates.h     | 10 +--
 deal.II/deal.II/include/grid/tria_accessor.h  |  3 +-
 .../include/grid/tria_accessor.templates.h    | 36 ++++----
 deal.II/deal.II/include/grid/tria_iterator.h  | 35 ++++----
 .../include/grid/tria_iterator.templates.h    | 56 ++++++-------
 .../deal.II/include/grid/tria_iterator_base.h | 20 +++--
 deal.II/deal.II/source/dofs/dof_handler.cc    |  2 +-
 deal.II/deal.II/source/grid/intergrid_map.cc  |  2 +-
 deal.II/deal.II/source/grid/tria.cc           | 84 ++++++++++---------
 deal.II/deal.II/source/grid/tria_accessor.cc  | 18 ++--
 .../source/multigrid/mg_dof_accessor.cc       | 10 +--
 .../source/multigrid/mg_dof_handler.cc        |  2 +-
 .../deal.II/source/multigrid/mg_smoother.cc   |  2 +-
 .../source/numerics/error_estimator.cc        |  8 +-
 deal.II/deal.II/source/numerics/vectors.cc    |  2 +-
 deal.II/doc/news/2001/c-3-2.html              | 11 +++
 deal.II/examples/step-12/step-12.cc           |  3 +-
 17 files changed, 167 insertions(+), 137 deletions(-)

diff --git a/deal.II/deal.II/include/dofs/dof_accessor.templates.h b/deal.II/deal.II/include/dofs/dof_accessor.templates.h
index 3de2e632a7..ca9f1af95c 100644
--- a/deal.II/deal.II/include/dofs/dof_accessor.templates.h
+++ b/deal.II/deal.II/include/dofs/dof_accessor.templates.h
@@ -176,7 +176,7 @@ DoFObjectAccessor<1,dim>::child (const unsigned int i) const
 						 dof_handler);
   
 #ifdef DEBUG
-  if (q.state() != past_the_end)
+  if (q.state() != IteratorState::past_the_end)
     Assert (q->used(), typename TriaAccessor<dim>::ExcUnusedCellAsChild());
 #endif
   return q;
@@ -297,7 +297,7 @@ DoFObjectAccessor<2,dim>::child (const unsigned int i) const
 						 dof_handler);
   
 #ifdef DEBUG
-  if (q.state() != past_the_end)
+  if (q.state() != IteratorState::past_the_end)
     Assert (q->used(), typename TriaAccessor<dim>::ExcUnusedCellAsChild());
 #endif
   return q;
@@ -435,7 +435,7 @@ DoFObjectAccessor<3,dim>::child (const unsigned int i) const
 						 dof_handler);
   
 #ifdef DEBUG
-  if (q.state() != past_the_end)
+  if (q.state() != IteratorState::past_the_end)
     Assert (q->used(), typename TriaAccessor<dim>::ExcUnusedCellAsChild());
 #endif
   return q;
@@ -464,7 +464,7 @@ DoFCellAccessor<dim>::neighbor (const unsigned int i) const
 					     dof_handler);
   
 #ifdef DEBUG
-  if (q.state() != past_the_end)
+  if (q.state() != IteratorState::past_the_end)
     Assert (q->used(), typename TriaAccessor<dim>::ExcUnusedCellAsNeighbor());
 #endif
   return q;
@@ -482,7 +482,7 @@ DoFCellAccessor<dim>::child (const unsigned int i) const
 					     dof_handler);
   
 #ifdef DEBUG
-  if (q.state() != past_the_end)
+  if (q.state() != IteratorState::past_the_end)
     Assert (q->used(), typename TriaAccessor<dim>::ExcUnusedCellAsChild());
 #endif
   return q;
diff --git a/deal.II/deal.II/include/grid/tria_accessor.h b/deal.II/deal.II/include/grid/tria_accessor.h
index 970f69cf7c..fa8ec1869b 100644
--- a/deal.II/deal.II/include/grid/tria_accessor.h
+++ b/deal.II/deal.II/include/grid/tria_accessor.h
@@ -161,13 +161,14 @@ class TriaAccessor
 				      *  present level.
 				      */
     int index () const;
+    
 				     /**
 				      *  Return the state of the iterator.
 				      *  For the different states an accessor 
 				      *  can be in, refer to the
 				      *  @ref{TriaRawIterator} documentation.
 				      */
-    IteratorState state () const;
+    IteratorState::IteratorState state () const;
 
 				     /**
 				      * Return a pointer to the triangulation
diff --git a/deal.II/deal.II/include/grid/tria_accessor.templates.h b/deal.II/deal.II/include/grid/tria_accessor.templates.h
index 1fd585ed08..522339a9c7 100644
--- a/deal.II/deal.II/include/grid/tria_accessor.templates.h
+++ b/deal.II/deal.II/include/grid/tria_accessor.templates.h
@@ -82,16 +82,16 @@ TriaAccessor<dim>::index () const
 
 template <int dim>
 inline
-IteratorState
+IteratorState::IteratorState
 TriaAccessor<dim>::state () const
 {
   if ((present_level>=0) && (present_index>=0))
-    return valid;
+    return IteratorState::valid;
   else
     if ((present_level==-1) && (present_index==-1))
-      return past_the_end;
+      return IteratorState::past_the_end;
     else
-      return invalid;
+      return IteratorState::invalid;
 };
 
 
@@ -113,7 +113,7 @@ inline
 bool
 TriaObjectAccessor<1,dim>::used () const
 {
-  Assert (state() == valid,
+  Assert (state() == IteratorState::valid,
 	  typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
   return tria->levels[present_level]->lines.used[present_index];
 };
@@ -163,7 +163,7 @@ TriaObjectAccessor<1,dim>::child (const unsigned int i) const
   TriaIterator<dim,TriaObjectAccessor<1,dim> >
     q (tria, present_level+1, child_index (i));
   
-  Assert ((q.state() == past_the_end) || q->used(),
+  Assert ((q.state() == IteratorState::past_the_end) || q->used(),
 	  typename TriaAccessor<dim>::ExcUnusedCellAsChild());
 
   return q;
@@ -187,7 +187,7 @@ inline
 bool
 TriaObjectAccessor<1,dim>::has_children () const
 {
-  Assert (state() == valid,
+  Assert (state() == IteratorState::valid,
 	  typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
   return (tria->levels[present_level]->lines.children[present_index] != -1);
 }
@@ -270,7 +270,7 @@ inline
 bool
 TriaObjectAccessor<2,dim>::used () const
 {
-  Assert (state() == valid,
+  Assert (state() == IteratorState::valid,
 	  typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
   return tria->levels[present_level]->quads.used[present_index];
 };
@@ -348,7 +348,7 @@ TriaObjectAccessor<2,dim>::child (const unsigned int i) const
   TriaIterator<dim,TriaObjectAccessor<2,dim> >
     q (tria, present_level+1, child_index (i));
   
-  Assert ((q.state() == past_the_end) || q->used(),
+  Assert ((q.state() == IteratorState::past_the_end) || q->used(),
 	  typename TriaAccessor<dim>::ExcUnusedCellAsChild());
 
   return q;
@@ -371,7 +371,7 @@ inline
 bool
 TriaObjectAccessor<2,dim>::has_children () const
 {
-  Assert (state() == valid,
+  Assert (state() == IteratorState::valid,
 	  typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
   return (tria->levels[present_level]->quads.children[present_index] != -1);
 };
@@ -456,7 +456,7 @@ inline
 bool
 TriaObjectAccessor<3,dim>::used () const
 {
-  Assert (state() == valid,
+  Assert (state() == IteratorState::valid,
 	  typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
   return tria->levels[present_level]->hexes.used[present_index];
 };
@@ -602,7 +602,7 @@ TriaObjectAccessor<3,dim>::child (const unsigned int i) const
   
   TriaIterator<dim,TriaObjectAccessor<3,dim> > q (tria, present_level+1, child_index (i));
   
-  Assert ((q.state() == past_the_end) || q->used(),
+  Assert ((q.state() == IteratorState::past_the_end) || q->used(),
 	  typename TriaAccessor<dim>::ExcUnusedCellAsChild());
 
   return q;
@@ -623,7 +623,7 @@ int TriaObjectAccessor<3,dim>::child_index (const unsigned int i) const
 template <int dim>
 bool TriaObjectAccessor<3,dim>::has_children () const
 {
-  Assert (state() == valid,
+  Assert (state() == IteratorState::valid,
 	  typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
   return (tria->levels[present_level]->hexes.children[present_index] != -1);
 };
@@ -714,7 +714,7 @@ inline
 bool
 TriaObjectAccessor<celldim,dim>::used () const
 {
-  Assert (state() == valid, ExcDereferenceInvalidObject());
+  Assert (state() == IteratorState::valid, ExcDereferenceInvalidObject());
   return tria->levels[present_level]->hexes.used[present_index];
 };
 
@@ -882,7 +882,7 @@ TriaObjectAccessor<celldim,dim>::child (const unsigned int i) const
   TriaIterator<dim,TriaObjectAccessor<celldim,dim> >
     q (tria, present_level+1, child_index (i));
   
-  Assert ((q.state() == past_the_end) || q->used(),
+  Assert ((q.state() == IteratorState::past_the_end) || q->used(),
 	  ExcUnusedCellAsChild());
 
   return q;
@@ -904,7 +904,7 @@ int TriaObjectAccessor<celldim,dim>::child_index (const unsigned int i) const
 template<int celldim, int dim>
 bool TriaObjectAccessor<celldim,dim>::has_children () const
 {
-  Assert (state() == valid,
+  Assert (state() == IteratorState::valid,
 	  typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
   return (tria->levels[present_level]->hexes.children[present_index] != -1);
 };
@@ -1140,7 +1140,7 @@ CellAccessor<dim>::neighbor (const unsigned int i) const
   TriaIterator<dim,CellAccessor<dim> >
     q (tria, neighbor_level (i), neighbor_index (i));
 
-  Assert ((q.state() == past_the_end) || q->used(),
+  Assert ((q.state() == IteratorState::past_the_end) || q->used(),
 	  typename TriaAccessor<dim>::ExcUnusedCellAsNeighbor());
 
   return q;
@@ -1156,7 +1156,7 @@ CellAccessor<dim>::child (const unsigned int i) const
   TriaIterator<dim,CellAccessor<dim> >
     q (tria, present_level+1, child_index (i));
 
-  Assert ((q.state() == past_the_end) || q->used(),
+  Assert ((q.state() == IteratorState::past_the_end) || q->used(),
 	  typename TriaAccessor<dim>::ExcUnusedCellAsChild());
 
   return q;
diff --git a/deal.II/deal.II/include/grid/tria_iterator.h b/deal.II/deal.II/include/grid/tria_iterator.h
index 3927c7c87d..0cb6ae6684 100644
--- a/deal.II/deal.II/include/grid/tria_iterator.h
+++ b/deal.II/deal.II/include/grid/tria_iterator.h
@@ -454,7 +454,7 @@ class TriaRawIterator :
 				     /**
 				      *  Return the state of the iterator.
 				      */
-    IteratorState state () const;
+    IteratorState::IteratorState state () const;
 
 				     /**
 				      * Print the iterator to @p{out}. The
@@ -851,7 +851,7 @@ inline
 const Accessor &
 TriaRawIterator<dim,Accessor>::operator * () const
 {
-  Assert (state() == valid, ExcDereferenceInvalidObject());
+  Assert (state() == IteratorState::valid, ExcDereferenceInvalidObject());
   return accessor;
 };
 
@@ -862,7 +862,7 @@ inline
 Accessor &
 TriaRawIterator<dim,Accessor>::operator * ()
 {
-  Assert (state() == valid, ExcDereferenceInvalidObject());
+  Assert (state() == IteratorState::valid, ExcDereferenceInvalidObject());
   return accessor;
 };
 
@@ -890,7 +890,7 @@ TriaRawIterator<dim,Accessor>::operator -> ()
 
 template <int dim, typename Accessor>
 inline
-IteratorState
+IteratorState::IteratorState
 TriaRawIterator<dim,Accessor>::state () const
 {
   return accessor.state ();
@@ -903,17 +903,18 @@ inline
 bool
 TriaRawIterator<dim,Accessor>::operator < (const TriaRawIterator &i) const
 {
-  Assert (state() != invalid, ExcDereferenceInvalidObject());
-  Assert (i.state() != invalid, ExcDereferenceInvalidObject());
+  Assert (state() != IteratorState::invalid, ExcDereferenceInvalidObject());
+  Assert (i.state() != IteratorState::invalid, ExcDereferenceInvalidObject());
   Assert (&accessor.get_triangulation() == &i.accessor.get_triangulation(),
 	  ExcInvalidComparison());
   
   return ((((accessor.level() < i.accessor.level()) ||
 	    ((accessor.level() == i.accessor.level()) &&
 	     (accessor.index() < i.accessor.index()))        ) &&
-	   (state()==valid)                                  &&
-	   (i.state()==valid)                                  ) ||
-	  ((state()==valid) && (i.state()==past_the_end)));
+	   (state()==IteratorState::valid)                     &&
+	   (i.state()==IteratorState::valid)                 ) ||
+	  ((state()==IteratorState::valid) &&
+	   (i.state()==IteratorState::past_the_end)));
 };
 
 
@@ -922,7 +923,7 @@ inline
 TriaRawIterator<dim,Accessor> &
 TriaRawIterator<dim,Accessor>::operator ++ ()
 {
-  Assert (state() == valid, ExcAdvanceInvalidObject());
+  Assert (state() == IteratorState::valid, ExcAdvanceInvalidObject());
 
   ++accessor;
   return *this;
@@ -935,7 +936,7 @@ inline
 TriaRawIterator<dim,Accessor> &
 TriaRawIterator<dim,Accessor>::operator -- ()
 {
-  Assert (state() == valid, ExcAdvanceInvalidObject());
+  Assert (state() == IteratorState::valid, ExcAdvanceInvalidObject());
 
   --accessor;
   return *this;
@@ -981,11 +982,11 @@ TriaIterator<dim,Accessor>::TriaIterator (const TriaRawIterator<dim,OtherAccesso
 #ifdef DEBUG
 				   // do this like this, because:
 				   // if we write
-				   // "Assert (past_the_end || used)"
+				   // "Assert (IteratorState::past_the_end || used)"
 				   // used() is called anyway, even if
-				   // state==past_the_end, and will then
+				   // state==IteratorState::past_the_end, and will then
 				   // throw the exception!
-  if (state() != past_the_end)
+  if (state() != IteratorState::past_the_end)
     Assert (accessor.used(),
 	    ExcAssignmentOfUnusedObject());
 #endif
@@ -1011,11 +1012,11 @@ TriaActiveIterator<dim,Accessor>::TriaActiveIterator (const TriaRawIterator<dim,
 #ifdef DEBUG
 				   // do this like this, because:
 				   // if we write
-				   // "Assert (past_the_end || used)"
+				   // "Assert (IteratorState::past_the_end || used)"
 				   // has_children() is called anyway, even if
-				   // state==past_the_end, and will then
+				   // state==IteratorState::past_the_end, and will then
 				   // throw the exception!
-  if (state() != past_the_end) 
+  if (state() != IteratorState::past_the_end) 
     Assert (accessor.has_children()==false,
 	    ExcAssignmentOfInactiveObject());
 #endif
diff --git a/deal.II/deal.II/include/grid/tria_iterator.templates.h b/deal.II/deal.II/include/grid/tria_iterator.templates.h
index 8cc96dc575..750d8236c7 100644
--- a/deal.II/deal.II/include/grid/tria_iterator.templates.h
+++ b/deal.II/deal.II/include/grid/tria_iterator.templates.h
@@ -131,11 +131,11 @@ TriaIterator<dim,Accessor>::TriaIterator (const TriaRawIterator<dim,Accessor> &i
 #ifdef DEBUG
 				   // do this like this, because:
 				   // if we write
-				   // "Assert (past_the_end || used)"
+				   // "Assert (IteratorState::past_the_end || used)"
 				   // used() is called anyway, even if
-				   // state==past_the_end, and will then
+				   // state==IteratorState::past_the_end, and will then
 				   // throw the exception!
-  if (state() != past_the_end)
+  if (state() != IteratorState::past_the_end)
     Assert (accessor.used(),
 	    ExcAssignmentOfUnusedObject());
 #endif  
@@ -153,11 +153,11 @@ TriaIterator<dim,Accessor>::TriaIterator (Triangulation<dim> *parent,
 #ifdef DEBUG
 				   // do this like this, because:
 				   // if we write
-				   // "Assert (past_the_end || used)"
+				   // "Assert (IteratorState::past_the_end || used)"
 				   // used() is called anyway, even if
-				   // state==past_the_end, and will then
+				   // state==IteratorState::past_the_end, and will then
 				   // throw the exception!
-  if (state() != past_the_end)
+  if (state() != IteratorState::past_the_end)
     Assert (accessor.used(),
 	    ExcAssignmentOfUnusedObject());
 #endif  
@@ -181,11 +181,11 @@ TriaIterator<dim,Accessor>::operator = (const TriaRawIterator<dim,Accessor> &i)
 #ifdef DEBUG
 				   // do this like this, because:
 				   // if we write
-				   // "Assert (past_the_end || used)"
+				   // "Assert (IteratorState::past_the_end || used)"
 				   // used() is called anyway, even if
-				   // state==past_the_end, and will then
+				   // state==IteratorState::past_the_end, and will then
 				   // throw the exception!
-  if (state() != past_the_end) 
+  if (state() != IteratorState::past_the_end) 
     Assert (accessor.used(),
 	    ExcAssignmentOfUnusedObject());
 #endif  
@@ -197,7 +197,7 @@ template <int dim, typename Accessor>
 inline
 TriaIterator<dim,Accessor> & TriaIterator<dim,Accessor>::operator ++ () {
   while (TriaRawIterator<dim,Accessor>::operator++(),
-	 (state() == valid))
+	 (state() == IteratorState::valid))
     if (accessor.used() == true)
       return *this;
   return *this;
@@ -219,7 +219,7 @@ inline
 TriaIterator<dim,Accessor> &
 TriaIterator<dim,Accessor>::operator -- () {
   while (TriaRawIterator<dim,Accessor>::operator--(),
-	 (state() == valid))
+	 (state() == IteratorState::valid))
     if (accessor.used() == true)
       return *this;
   return *this;
@@ -260,11 +260,11 @@ TriaActiveIterator<dim,Accessor>::TriaActiveIterator (const TriaRawIterator<dim,
 #ifdef DEBUG
 				   // do this like this, because:
 				   // if we write
-				   // "Assert (past_the_end || used)"
+				   // "Assert (IteratorState::past_the_end || used)"
 				   // has_children() is called anyway, even if
-				   // state==past_the_end, and will then
+				   // state==IteratorState::past_the_end, and will then
 				   // throw the exception!
-  if (state() != past_the_end) 
+  if (state() != IteratorState::past_the_end) 
     Assert (accessor.has_children()==false,
 	    ExcAssignmentOfInactiveObject());
 #endif  
@@ -279,11 +279,11 @@ TriaActiveIterator<dim,Accessor>::TriaActiveIterator (const TriaIterator<dim,Acc
 #ifdef DEBUG
 				   // do this like this, because:
 				   // if we write
-				   // "Assert (past_the_end || used)"
+				   // "Assert (IteratorState::past_the_end || used)"
 				   // has_children() is called anyway, even if
-				   // state==past_the_end, and will then
+				   // state==IteratorState::past_the_end, and will then
 				   // throw the exception!
-  if (state() != past_the_end) 
+  if (state() != IteratorState::past_the_end) 
     Assert (accessor.has_children()==false,
 	    ExcAssignmentOfInactiveObject());
 #endif  
@@ -301,11 +301,11 @@ TriaActiveIterator<dim,Accessor>::TriaActiveIterator (Triangulation<dim> *parent
 #ifdef DEBUG
 				   // do this like this, because:
 				   // if we write
-				   // "Assert (past_the_end || used)"
+				   // "Assert (IteratorState::past_the_end || used)"
 				   // has_children() is called anyway, even if
-				   // state==past_the_end, and will then
+				   // state==IteratorState::past_the_end, and will then
 				   // throw the exception!
-  if (state() != past_the_end) 
+  if (state() != IteratorState::past_the_end) 
     Assert (accessor.has_children()==false,
 	    ExcAssignmentOfInactiveObject());
 #endif  
@@ -329,11 +329,11 @@ TriaActiveIterator<dim,Accessor>::operator = (const TriaRawIterator<dim,Accessor
 #ifdef DEBUG
 				   // do this like this, because:
 				   // if we write
-				   // "Assert (past_the_end || used)"
+				   // "Assert (IteratorState::past_the_end || used)"
 				   // has_chidlren() is called anyway, even if
-				   // state==past_the_end, and will then
+				   // state==IteratorState::past_the_end, and will then
 				   // throw the exception!
-  if (state() != past_the_end) 
+  if (state() != IteratorState::past_the_end) 
     Assert (accessor.used() && accessor.has_children()==false,
 	    ExcAssignmentOfInactiveObject());
 #endif  
@@ -349,11 +349,11 @@ TriaActiveIterator<dim,Accessor>::operator = (const TriaIterator<dim,Accessor> &
 #ifdef DEBUG
 				   // do this like this, because:
 				   // if we write
-				   // "Assert (past_the_end || used)"
+				   // "Assert (IteratorState::past_the_end || used)"
 				   // has_children() is called anyway, even if
-				   // state==past_the_end, and will then
+				   // state==IteratorState::past_the_end, and will then
 				   // throw the exception!
-  if (state() != past_the_end) 
+  if (state() != IteratorState::past_the_end) 
     Assert (accessor.has_children()==false,
 	    ExcAssignmentOfInactiveObject());
 #endif  
@@ -366,7 +366,7 @@ inline
 TriaActiveIterator<dim,Accessor> &
 TriaActiveIterator<dim,Accessor>::operator ++ () {
   while (TriaIterator<dim,Accessor>::operator++(),
-	 (state() == valid))
+	 (state() == IteratorState::valid))
     if (accessor.has_children() == false)
       return *this;
   return *this;
@@ -389,7 +389,7 @@ inline
 TriaActiveIterator<dim,Accessor> &
 TriaActiveIterator<dim,Accessor>::operator -- () {
   while (TriaIterator<dim,Accessor>::operator--(),
-	 (state() == valid))
+	 (state() == IteratorState::valid))
     if (accessor.has_children() == false)
       return *this;
   return *this;
diff --git a/deal.II/deal.II/include/grid/tria_iterator_base.h b/deal.II/deal.II/include/grid/tria_iterator_base.h
index 89af62eea3..7f07595410 100644
--- a/deal.II/deal.II/include/grid/tria_iterator_base.h
+++ b/deal.II/deal.II/include/grid/tria_iterator_base.h
@@ -16,16 +16,26 @@
 
 #include <base/config.h>
 
+
+/**
+ * Namespace in which an enumeration is declared that denotes the
+ * states in which an iterator can be in.
+ */
+namespace IteratorState
+{
+  
 /**
  *   The three states an iterator can be in: valid, past-the-end and
  *   invalid.
  */
-enum IteratorState
-{
-      valid,
-      past_the_end,
-      invalid
+  enum IteratorState
+  {
+	valid,
+	past_the_end,
+	invalid
+  };
 };
 
 
+
 #endif
diff --git a/deal.II/deal.II/source/dofs/dof_handler.cc b/deal.II/deal.II/source/dofs/dof_handler.cc
index fb1bb3fc4b..0e31262b8b 100644
--- a/deal.II/deal.II/source/dofs/dof_handler.cc
+++ b/deal.II/deal.II/source/dofs/dof_handler.cc
@@ -1351,7 +1351,7 @@ unsigned int DoFHandler<1>::distribute_dofs_on_cell (active_cell_iterator &cell,
     {
       cell_iterator neighbor = cell->neighbor(v);
 
-      if (neighbor.state() == valid)
+      if (neighbor.state() == IteratorState::valid)
 	{
 					   // find true neighbor; may be its
 					   // a child of @p{neighbor}
diff --git a/deal.II/deal.II/source/grid/intergrid_map.cc b/deal.II/deal.II/source/grid/intergrid_map.cc
index 6fa4bf0b68..64d7fdd69f 100644
--- a/deal.II/deal.II/source/grid/intergrid_map.cc
+++ b/deal.II/deal.II/source/grid/intergrid_map.cc
@@ -163,7 +163,7 @@ template <template <int> class GridClass, int dim>
 typename InterGridMap<GridClass,dim>::cell_iterator
 InterGridMap<GridClass,dim>::operator [] (const cell_iterator &source_cell) const
 {
-  Assert (source_cell.state() == valid,
+  Assert (source_cell.state() == IteratorState::valid,
 	  ExcInvalidKey (source_cell));
   Assert (source_cell->level() <= static_cast<int>(mapping.size()),
 	  ExcInvalidKey (source_cell));
diff --git a/deal.II/deal.II/source/grid/tria.cc b/deal.II/deal.II/source/grid/tria.cc
index 550df0c14c..f9d565c1ec 100644
--- a/deal.II/deal.II/source/grid/tria.cc
+++ b/deal.II/deal.II/source/grid/tria.cc
@@ -3209,10 +3209,10 @@ Triangulation<dim>::begin_line (const unsigned int level) const
 {
   				   // level is checked in begin_raw
   raw_line_iterator ri = begin_raw_line (level);
-  if (ri.state() != valid)
+  if (ri.state() != IteratorState::valid)
     return ri;
   while (ri->used() == false)
-    if ((++ri).state() != valid)
+    if ((++ri).state() != IteratorState::valid)
       return ri;
   return ri;
 };
@@ -3225,10 +3225,10 @@ Triangulation<dim>::begin_quad (const unsigned int level) const
 {
   				   // level is checked in begin_raw
   raw_quad_iterator ri = begin_raw_quad (level);
-  if (ri.state() != valid)
+  if (ri.state() != IteratorState::valid)
     return ri;
   while (ri->used() == false)
-    if ((++ri).state() != valid)
+    if ((++ri).state() != IteratorState::valid)
       return ri;
   return ri;
 };
@@ -3241,10 +3241,10 @@ Triangulation<dim>::begin_hex (const unsigned int level) const
 {
   				   // level is checked in begin_raw
   raw_hex_iterator ri = begin_raw_hex (level);
-  if (ri.state() != valid)
+  if (ri.state() != IteratorState::valid)
     return ri;
   while (ri->used() == false)
-    if ((++ri).state() != valid)
+    if ((++ri).state() != IteratorState::valid)
       return ri;
   return ri;
 };
@@ -3257,10 +3257,10 @@ Triangulation<dim>::begin_active_line (const unsigned int level) const
 {
   				   // level is checked in begin_raw
   line_iterator i = begin_line (level);
-  if (i.state() != valid)
+  if (i.state() != IteratorState::valid)
     return i;
   while (i->has_children())
-    if ((++i).state() != valid)
+    if ((++i).state() != IteratorState::valid)
       return i;
   return i;
 };
@@ -3273,10 +3273,10 @@ Triangulation<dim>::begin_active_quad (const unsigned int level) const
 {
   				   // level is checked in begin_raw
   quad_iterator i = begin_quad (level);
-  if (i.state() != valid)
+  if (i.state() != IteratorState::valid)
     return i;
   while (i->has_children())
-    if ((++i).state() != valid)
+    if ((++i).state() != IteratorState::valid)
       return i;
   return i;
 };
@@ -3289,10 +3289,10 @@ Triangulation<dim>::begin_active_hex (const unsigned int level) const
 {
   				   // level is checked in begin_raw
   hex_iterator i = begin_hex (level);
-  if (i.state() != valid)
+  if (i.state() != IteratorState::valid)
     return i;
   while (i->has_children())
-    if ((++i).state() != valid)
+    if ((++i).state() != IteratorState::valid)
       return i;
   return i;
 };
@@ -3402,7 +3402,7 @@ Triangulation<dim>::last_line (const unsigned int level) const {
   raw_line_iterator ri = last_raw_line(level);
   if (ri->used()==true)
     return ri;
-  while ((--ri).state() == valid)
+  while ((--ri).state() == IteratorState::valid)
     if (ri->used()==true)
       return ri;
   return ri;
@@ -3416,7 +3416,7 @@ Triangulation<dim>::last_quad (const unsigned int level) const {
   raw_quad_iterator ri = last_raw_quad(level);
   if (ri->used()==true)
     return ri;
-  while ((--ri).state() == valid)
+  while ((--ri).state() == IteratorState::valid)
     if (ri->used()==true)
       return ri;
   return ri;
@@ -3430,7 +3430,7 @@ Triangulation<dim>::last_hex (const unsigned int level) const {
   raw_hex_iterator ri = last_raw_hex(level);
   if (ri->used()==true)
     return ri;
-  while ((--ri).state() == valid)
+  while ((--ri).state() == IteratorState::valid)
     if (ri->used()==true)
       return ri;
   return ri;
@@ -3465,7 +3465,7 @@ Triangulation<dim>::last_active_line (const unsigned int level) const {
   line_iterator i = last_line(level);
   if (i->has_children()==false)
     return i;
-  while ((--i).state() == valid)
+  while ((--i).state() == IteratorState::valid)
     if (i->has_children()==false)
       return i;
   return i;
@@ -3479,7 +3479,7 @@ Triangulation<dim>::last_active_quad (const unsigned int level) const {
   quad_iterator i = last_quad(level);
   if (i->has_children()==false)
     return i;
-  while ((--i).state() == valid)
+  while ((--i).state() == IteratorState::valid)
     if (i->has_children()==false)
       return i;
   return i;
@@ -3493,7 +3493,7 @@ Triangulation<dim>::last_active_hex (const unsigned int level) const {
   hex_iterator i = last_hex(level);
   if (i->has_children()==false)
     return i;
-  while ((--i).state() == valid)
+  while ((--i).state() == IteratorState::valid)
     if (i->has_children()==false)
       return i;
   return i;
@@ -4155,7 +4155,7 @@ void Triangulation<1>::execute_refinement () {
 					     // (refer to \Ref{TriangulationLevel<0>}
 					     // for details)
 	    first_child->set_neighbor (1, second_child);
-	    if (cell->neighbor(0).state() != valid)
+	    if (cell->neighbor(0).state() != IteratorState::valid)
 	      first_child->set_neighbor (0, cell->neighbor(0));
 	    else
 	      if (cell->neighbor(0)->active())
@@ -4194,7 +4194,7 @@ void Triangulation<1>::execute_refinement () {
 	    second_child->set_neighbor (0, first_child);
 	    second_child->set_material_id (cell->material_id());
 	    second_child->set_subdomain_id (cell->subdomain_id());	    
-	    if (cell->neighbor(1).state() != valid)
+	    if (cell->neighbor(1).state() != IteratorState::valid)
 	      second_child->set_neighbor (1, cell->neighbor(1));
 	    else
 	      if (cell->neighbor(1)->active())
@@ -4304,7 +4304,7 @@ void Triangulation<2>::execute_refinement () {
 	      {
 		const cell_iterator neighbor = acell->neighbor(nb);
 						 // if cell is at boundary
-		if (neighbor.state() != valid) 
+		if (neighbor.state() != IteratorState::valid) 
 		  {
 						     // new midpoint vertex
 						     // necessary
@@ -4435,7 +4435,7 @@ void Triangulation<2>::execute_refinement () {
 #ifdef DEBUG
 	    for (unsigned int neighbor=0;
 		 neighbor<GeometryInfo<dim>::faces_per_cell; ++neighbor)
-	      if (cell->neighbor(neighbor).state() == valid)
+	      if (cell->neighbor(neighbor).state() == IteratorState::valid)
 		Assert (((cell->neighbor(neighbor)->level() == cell->level()) &&
 			 (cell->neighbor(neighbor)->coarsen_flag_set() == false))  ||
 			((cell->neighbor(neighbor)->level() == cell->level()-1) &&
@@ -4539,7 +4539,7 @@ void Triangulation<2>::execute_refinement () {
 	    for (unsigned int nb=0; nb<4; ++nb)
 	      {
 		bool neighbor_refined=false;
-		if (cell->neighbor(nb).state() == valid)
+		if (cell->neighbor(nb).state() == IteratorState::valid)
 		  if (cell->neighbor(nb)->active() == false)
 						     // (ask in two if-statements,
 						     // since otherwise both
@@ -4807,7 +4807,7 @@ void Triangulation<2>::execute_refinement () {
 	    const int neighbor_mapping[8] = {0,1, 1,2, 2,3, 3,0};
 	    
 	    for (unsigned int nb=0; nb<8; ++nb)
-	      if (neighbors[nb].state() == valid)
+	      if (neighbors[nb].state() == IteratorState::valid)
 		if (neighbors[nb]->level() == level+1)
 						   // neighbor is refined cell
 		  neighbors[nb]->set_neighbor(neighbors_neighbor[nb],
@@ -5391,7 +5391,7 @@ void Triangulation<3>::execute_refinement ()
 #ifdef DEBUG
 	    for (unsigned int neighbor=0;
 		 neighbor<GeometryInfo<dim>::faces_per_cell; ++neighbor)
-	      if (hex->neighbor(neighbor).state() == valid)
+	      if (hex->neighbor(neighbor).state() == IteratorState::valid)
 		Assert (((hex->neighbor(neighbor)->level() == hex->level()) &&
 			 (hex->neighbor(neighbor)->coarsen_flag_set() == false))  ||
 			((hex->neighbor(neighbor)->level() == hex->level()-1) &&
@@ -5935,7 +5935,7 @@ void Triangulation<3>::execute_refinement ()
 		const cell_iterator neighbor = hex->neighbor(face);
 
 						 // if no neighbor
-		if (neighbor.state() != valid)
+		if (neighbor.state() != IteratorState::valid)
 		  for (unsigned int child_face=0;
 		       child_face<GeometryInfo<dim>::subfaces_per_face;
 		       ++child_face)
@@ -5993,7 +5993,8 @@ void Triangulation<3>::execute_refinement ()
 			    neighbor_cells[face][c]
 			      = neighbor->child(GeometryInfo<dim>::child_cell_on_face(nb_nb, c));
 			    
-			    Assert (neighbor_cells[face][c].state() == valid,
+			    Assert (neighbor_cells[face][c].state() ==
+				    IteratorState::valid,
 				    ExcInternalError());
 			    Assert (!neighbor_cells[face][c]->has_children(),
 				    ExcInternalError());
@@ -6071,7 +6072,8 @@ void Triangulation<3>::execute_refinement ()
 	    for (unsigned int nb=0; nb<GeometryInfo<dim>::faces_per_cell; ++nb)
 	      for (unsigned int subface=0;
 		   subface<GeometryInfo<dim>::subfaces_per_face; ++subface)
-		if ((neighbor_cells[nb][subface].state() == valid) &&
+		if ((neighbor_cells[nb][subface].state() ==
+		     IteratorState::valid) &&
 		    (neighbor_cells[nb][subface]->level() ==
 		     hex->level()+1))
 		  {
@@ -6439,7 +6441,7 @@ void Triangulation<dim>::fix_coarsen_flags () {
 	  for (unsigned int n=0; n<GeometryInfo<dim>::faces_per_cell; ++n)
 	    {
 	      const cell_iterator child_neighbor = cell->child(c)->neighbor(n);
-	      if (child_neighbor.state() == valid)
+	      if (child_neighbor.state() == IteratorState::valid)
 		if (child_neighbor->has_children() ||
 						     // neighbor has children,
 						     // then only allow coarsening
@@ -6672,7 +6674,7 @@ bool Triangulation<dim>::prepare_coarsening_and_refinement () {
 			   n<GeometryInfo<dim>::faces_per_cell; ++n)
 			{
 			  const cell_iterator neighbor = cell->neighbor(n);
-			  if (neighbor.state() == valid)
+			  if (neighbor.state() == IteratorState::valid)
 			    {
 			      ++n_neighbors;
 
@@ -6766,10 +6768,10 @@ bool Triangulation<dim>::prepare_coarsening_and_refinement () {
 		    for (unsigned int n=0; n<GeometryInfo<dim>::faces_per_cell; ++n) 
 		      {
 			const cell_iterator neighbor = cell->neighbor(n);
-			if (neighbor.state() == valid)
+			if (neighbor.state() == IteratorState::valid)
 			  ++total_neighbors;
 
-			if (neighbor.state() == valid)
+			if (neighbor.state() == IteratorState::valid)
 			  if ((neighbor->active() &&
 			       !neighbor->refine_flag_set()) ||
 			      (neighbor->level() == cell->level()-1))
@@ -7117,7 +7119,7 @@ bool Triangulation<dim>::prepare_coarsening_and_refinement () {
 	  {
 					     // loop over neighbors of cell
 	    for (unsigned int i=0; i<GeometryInfo<dim>::faces_per_cell; ++i)
-	      if (cell->neighbor(i).state() == valid)
+	      if (cell->neighbor(i).state() == IteratorState::valid)
 		{
 						   // regularisation?
 		  if ((cell->neighbor_level(i) == cell->level()-1)
@@ -7212,7 +7214,7 @@ void Triangulation<1>::delete_children (cell_iterator &cell) {
   
 				   // first do it for the cells to the
 				   // left
-  if (cell->neighbor(0).state() == valid)
+  if (cell->neighbor(0).state() == IteratorState::valid)
     if (cell->neighbor(0)->has_children())
       {
 	cell_iterator neighbor = cell->neighbor(0);
@@ -7238,7 +7240,7 @@ void Triangulation<1>::delete_children (cell_iterator &cell) {
 
   				   // now do it for the cells to the
 				   // left
-  if (cell->neighbor(1).state() == valid)
+  if (cell->neighbor(1).state() == IteratorState::valid)
     if (cell->neighbor(1)->has_children())
       {
 	cell_iterator neighbor = cell->neighbor(1);
@@ -7315,7 +7317,7 @@ void Triangulation<2>::delete_children (cell_iterator &cell) {
       {
 	const cell_iterator neighbor = cell->child(child)->neighbor(n);
 					 // do nothing if at boundary
-	if (neighbor.state() != valid)
+	if (neighbor.state() != IteratorState::valid)
 	  continue;
 	
 	Assert ((neighbor->level()==cell->level()) ||
@@ -7382,7 +7384,7 @@ void Triangulation<2>::delete_children (cell_iterator &cell) {
 				   // one less or the same as that of
 				   // cell
   for (unsigned int face=0; face<GeometryInfo<dim>::faces_per_cell; ++face) 
-    if ((cell->neighbor(face).state() != valid) ||
+    if ((cell->neighbor(face).state() != IteratorState::valid) ||
 	(cell->neighbor(face)->level() == cell->level()-1) ||
 	((cell->neighbor(face)->level() == cell->level()) &&
 	 !cell->neighbor(face)->has_children()))
@@ -7444,7 +7446,7 @@ void Triangulation<3>::delete_children (cell_iterator &cell) {
       {
 	const cell_iterator neighbor = cell->child(child)->neighbor(n);
 					 // do nothing if at boundary
-	if (neighbor.state() != valid)
+	if (neighbor.state() != IteratorState::valid)
 	  continue;
 	
 	Assert ((neighbor->level()==cell->level()) ||
@@ -7544,7 +7546,7 @@ void Triangulation<3>::delete_children (cell_iterator &cell) {
 				   // one less or the same as that of
 				   // cell
   for (unsigned int face=0; face<GeometryInfo<dim>::faces_per_cell; ++face) 
-    if ((cell->neighbor(face).state() != valid) ||
+    if ((cell->neighbor(face).state() != IteratorState::valid) ||
 	(cell->neighbor(face)->level() == cell->level()-1) ||
 	((cell->neighbor(face)->level() == cell->level()) &&
 	 !cell->neighbor(face)->has_children()))
@@ -7653,7 +7655,7 @@ void Triangulation<3>::delete_children (cell_iterator &cell) {
     {
       const cell_iterator neighbor = cell->neighbor(nb);
 				       // do nothing if at boundary
-      if (neighbor.state() != valid)
+      if (neighbor.state() != IteratorState::valid)
 	continue;
 
       Assert (neighbor->level() == cell->level(),
@@ -7688,7 +7690,7 @@ void Triangulation<3>::delete_children (cell_iterator &cell) {
 	{
 	  const cell_iterator neighbor_neighbor = neighbor->neighbor(nb_nb);
 					   // do nothing if at boundary
-	  if (neighbor_neighbor.state() != valid)
+	  if (neighbor_neighbor.state() != IteratorState::valid)
 	    continue;
 
 	  Assert ((neighbor_neighbor->level() == cell->level()) ||
diff --git a/deal.II/deal.II/source/grid/tria_accessor.cc b/deal.II/deal.II/source/grid/tria_accessor.cc
index cb8c7676da..488493b1fa 100644
--- a/deal.II/deal.II/source/grid/tria_accessor.cc
+++ b/deal.II/deal.II/source/grid/tria_accessor.cc
@@ -54,7 +54,7 @@ TriaObjectAccessor<1, dim>::vertex (const unsigned int i) const
 template <int dim>
 void TriaObjectAccessor<1, dim>::set_used_flag () const
 {
-  Assert (state() == valid,
+  Assert (state() == IteratorState::valid,
 	  typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
   tria->levels[present_level]->lines.used[present_index] = true;
 };
@@ -64,7 +64,7 @@ void TriaObjectAccessor<1, dim>::set_used_flag () const
 template <int dim>
 void TriaObjectAccessor<1, dim>::clear_used_flag () const
 {
-  Assert (state() == valid,
+  Assert (state() == IteratorState::valid,
 	  typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
   tria->levels[present_level]->lines.used[present_index] = false;
 };
@@ -256,7 +256,8 @@ template <int dim>
 void
 TriaObjectAccessor<2, dim>::set_used_flag () const
 {
-  Assert (state() == valid, typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
+  Assert (state() == IteratorState::valid,
+	  typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
   tria->levels[present_level]->quads.used[present_index] = true;
 };
 
@@ -265,7 +266,8 @@ TriaObjectAccessor<2, dim>::set_used_flag () const
 template <int dim>
 void TriaObjectAccessor<2, dim>::clear_used_flag () const
 {
-  Assert (state() == valid, typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
+  Assert (state() == IteratorState::valid,
+	  typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
   tria->levels[present_level]->quads.used[present_index] = false;
 };
 
@@ -649,7 +651,8 @@ TriaObjectAccessor<3, dim>::vertex (const unsigned int i) const
 template <int dim>
 void TriaObjectAccessor<3, dim>::set_used_flag () const
 {
-  Assert (state() == valid, typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
+  Assert (state() == IteratorState::valid,
+	  typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
   tria->levels[present_level]->hexes.used[present_index] = true;
 };
 
@@ -658,7 +661,8 @@ void TriaObjectAccessor<3, dim>::set_used_flag () const
 template <int dim>
 void TriaObjectAccessor<3, dim>::clear_used_flag () const
 {
-  Assert (state() == valid, typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
+  Assert (state() == IteratorState::valid,
+	  typename TriaAccessor<dim>::ExcDereferenceInvalidObject());
   tria->levels[present_level]->hexes.used[present_index] = false;
 };
 
@@ -1743,7 +1747,7 @@ void CellAccessor<dim>::set_neighbor (const unsigned int i,
   Assert (i<GeometryInfo<dim>::faces_per_cell,
 	  typename TriaAccessor<dim>::ExcInvalidNeighbor(i));
 
-  if (pointer.state() == valid)
+  if (pointer.state() == IteratorState::valid)
     {
       tria->levels[present_level]->
 	neighbors[present_index*GeometryInfo<dim>::faces_per_cell+i].first
diff --git a/deal.II/deal.II/source/multigrid/mg_dof_accessor.cc b/deal.II/deal.II/source/multigrid/mg_dof_accessor.cc
index 294fb78c7c..ae06466448 100644
--- a/deal.II/deal.II/source/multigrid/mg_dof_accessor.cc
+++ b/deal.II/deal.II/source/multigrid/mg_dof_accessor.cc
@@ -172,7 +172,7 @@ MGDoFObjectAccessor<1, dim>::child (const unsigned int i) const
 						    mg_dof_handler);
   
 #ifdef DEBUG
-  if (q.state() != past_the_end)
+  if (q.state() != IteratorState::past_the_end)
     Assert (q->used(), typename TriaAccessor<dim>::ExcUnusedCellAsChild());
 #endif
   return q;
@@ -354,7 +354,7 @@ MGDoFObjectAccessor<2, dim>::child (const unsigned int i) const
 						    mg_dof_handler);
   
 #ifdef DEBUG
-  if (q.state() != past_the_end)
+  if (q.state() != IteratorState::past_the_end)
     Assert (q->used(), typename TriaAccessor<dim>::ExcUnusedCellAsChild());
 #endif
   return q;
@@ -558,7 +558,7 @@ MGDoFObjectAccessor<3, dim>::child (const unsigned int i) const {
 						    mg_dof_handler);
   
 #ifdef DEBUG
-  if (q.state() != past_the_end)
+  if (q.state() != IteratorState::past_the_end)
     Assert (q->used(), typename TriaAccessor<dim>::ExcUnusedCellAsChild());
 #endif
   return q;
@@ -584,7 +584,7 @@ MGDoFCellAccessor<dim>::neighbor (const unsigned int i) const {
 					       mg_dof_handler);
   
 #ifdef DEBUG
-  if (q.state() != past_the_end)
+  if (q.state() != IteratorState::past_the_end)
     Assert (q->used(), typename TriaAccessor<dim>::ExcUnusedCellAsNeighbor());
 #endif
   return q;
@@ -600,7 +600,7 @@ MGDoFCellAccessor<dim>::child (const unsigned int i) const {
 					       mg_dof_handler);
   
 #ifdef DEBUG
-  if (q.state() != past_the_end)
+  if (q.state() != IteratorState::past_the_end)
     Assert (q->used(), typename TriaAccessor<dim>::ExcUnusedCellAsChild());
 #endif
   return q;
diff --git a/deal.II/deal.II/source/multigrid/mg_dof_handler.cc b/deal.II/deal.II/source/multigrid/mg_dof_handler.cc
index ac0b253e75..a82bdc2162 100644
--- a/deal.II/deal.II/source/multigrid/mg_dof_handler.cc
+++ b/deal.II/deal.II/source/multigrid/mg_dof_handler.cc
@@ -1221,7 +1221,7 @@ MGDoFHandler<1>::distribute_dofs_on_cell (cell_iterator &cell,
       {
 	cell_iterator neighbor = cell->neighbor(v);
 	
-	if (neighbor.state() == valid)
+	if (neighbor.state() == IteratorState::valid)
 	  {
 					     // has neighbor already been processed?
 	    if (neighbor->user_flag_set() &&
diff --git a/deal.II/deal.II/source/multigrid/mg_smoother.cc b/deal.II/deal.II/source/multigrid/mg_smoother.cc
index fb505e35e1..6d0789d709 100644
--- a/deal.II/deal.II/source/multigrid/mg_smoother.cc
+++ b/deal.II/deal.II/source/multigrid/mg_smoother.cc
@@ -83,7 +83,7 @@ MGSmootherContinuous::MGSmootherContinuous (const MGDoFHandler<dim> &mg_dof,
       for (typename MGDoFHandler<dim>::cell_iterator cell=mg_dof.begin(level);
 	   cell != mg_dof.end(level); ++cell)
 	for (unsigned int face=0; face<GeometryInfo<dim>::faces_per_cell; ++face)
-	  if ((cell->neighbor(face).state() == valid) &&
+	  if ((cell->neighbor(face).state() == IteratorState::valid) &&
 	      (static_cast<unsigned int>(cell->neighbor(face)->level())
 	       == level-1))
 	    {
diff --git a/deal.II/deal.II/source/numerics/error_estimator.cc b/deal.II/deal.II/source/numerics/error_estimator.cc
index 7c6460dbf5..4020b0ed7c 100644
--- a/deal.II/deal.II/source/numerics/error_estimator.cc
+++ b/deal.II/deal.II/source/numerics/error_estimator.cc
@@ -304,7 +304,7 @@ void KellyErrorEstimator<1>::estimate (const Mapping<1>                    &mapp
 	{
 					   // find right active neighbor
 	  DoFHandler<dim>::cell_iterator neighbor = cell->neighbor(n);
-	  if (neighbor.state() == valid)
+	  if (neighbor.state() == IteratorState::valid)
 	    while (neighbor->has_children())
 	      neighbor = neighbor->child(n==0 ? 1 : 0);
       
@@ -315,7 +315,7 @@ void KellyErrorEstimator<1>::estimate (const Mapping<1>                    &mapp
 	  for (unsigned int s=0; s<n_solution_vectors; ++s)
 	    fe_values.get_function_grads (*solutions[s], gradients_here[s]);
 
-	  if (neighbor.state() == valid)
+	  if (neighbor.state() == IteratorState::valid)
 	    {
 	      fe_values.reinit (neighbor);
 
@@ -780,7 +780,7 @@ integrate_over_regular_face (Data                       &data,
 				     // internal face; integrate jump
 				     // of gradient across this face
     {
-      Assert (cell->neighbor(face_no).state() == valid,
+      Assert (cell->neighbor(face_no).state() == IteratorState::valid,
 	      ExcInternalError());      
       
       const active_cell_iterator neighbor = cell->neighbor(face_no);
@@ -947,7 +947,7 @@ integrate_over_irregular_face (Data                       &data,
 		     n_components       = data.dof_handler.get_fe().n_components(),
 		     n_solution_vectors = data.n_solution_vectors;
 
-  Assert (neighbor.state() == valid, ExcInternalError());
+  Assert (neighbor.state() == IteratorState::valid, ExcInternalError());
   Assert (neighbor->has_children(), ExcInternalError());
 				   // set up a vector of the gradients
 				   // of the finite element function
diff --git a/deal.II/deal.II/source/numerics/vectors.cc b/deal.II/deal.II/source/numerics/vectors.cc
index 5714d5a6a0..c2f8c94d66 100644
--- a/deal.II/deal.II/source/numerics/vectors.cc
+++ b/deal.II/deal.II/source/numerics/vectors.cc
@@ -723,7 +723,7 @@ VectorTools::interpolate_boundary_values (const Mapping<1>         &,
 				   // grid to its end and then going
 				   // to the children
   DoFHandler<1>::cell_iterator outermost_cell = dof.begin(0);
-  while (outermost_cell->neighbor(direction).state() == valid)
+  while (outermost_cell->neighbor(direction).state() == IteratorState::valid)
     outermost_cell = outermost_cell->neighbor(direction);
   
   while (outermost_cell->has_children())
diff --git a/deal.II/doc/news/2001/c-3-2.html b/deal.II/doc/news/2001/c-3-2.html
index 42663f0237..2e0823860d 100644
--- a/deal.II/doc/news/2001/c-3-2.html
+++ b/deal.II/doc/news/2001/c-3-2.html
@@ -220,6 +220,17 @@ documentation, etc</a>.
 <h3>deal.II</h3>
 
 <ol>
+  <li> <p>
+       Changed: The <code class="class">IteratorState</code> enum used
+       to indicate the state in which an iterator can be is now
+       enclosed in a namespace of the same name, to take its members
+       out of the global namespace. When using one of these members,
+       you now have to prefix it by <code
+       class="class">IteratorState::</code>.
+       <br>
+       (RH, WB 2001/11/30)
+       </p>
+
   <li> <p>
        Changed: The <code class="class">NormType</code> enum used to
        indicate the norm the <code
diff --git a/deal.II/examples/step-12/step-12.cc b/deal.II/examples/step-12/step-12.cc
index 953ade8454..b9111306dd 100644
--- a/deal.II/examples/step-12/step-12.cc
+++ b/deal.II/examples/step-12/step-12.cc
@@ -1279,7 +1279,8 @@ void DGMethod<dim>::assemble_system2 ()
 	    }
 	  else
 	    {
-	      Assert (cell->neighbor(face_no).state() == valid, ExcInternalError());
+	      Assert (cell->neighbor(face_no).state() == IteratorState::valid,
+		      ExcInternalError());
 	      typename DoFHandler<dim>::cell_iterator neighbor=
 		cell->neighbor(face_no);
 					       // Case 2:
-- 
2.39.5