From 48900bf3ab093d85f0803f1a179dedb23c1aa93f Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@math.tamu.edu>
Date: Mon, 1 May 2006 16:18:50 +0000
Subject: [PATCH] Add a dummy operator[] to make generic programming for
 non-hp/hp accessors simpler.

git-svn-id: https://svn.dealii.org/trunk@12940 0785d39b-7218-0410-832d-ea1e28bc413d
---
 deal.II/deal.II/include/fe/fe.h | 66 +++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)

diff --git a/deal.II/deal.II/include/fe/fe.h b/deal.II/deal.II/include/fe/fe.h
index da31faf488..5a2cc23637 100644
--- a/deal.II/deal.II/include/fe/fe.h
+++ b/deal.II/deal.II/include/fe/fe.h
@@ -427,6 +427,51 @@ class FiniteElement : public Subscriptor,
 				      */
     virtual std::string get_name () const = 0;
 
+				     /**
+				      * This operator returns a
+				      * reference to the present
+				      * object if the argument given
+				      * equals to zero. While this
+				      * does not seem particularly
+				      * useful, it is helpful in
+				      * writing code that works with
+				      * both ::DoFHandler and the hp
+				      * version hp::DoFHandler, since
+				      * one can then write code like
+				      * this:
+				      * @verbatim
+				      *   dofs_per_cell
+				      *     = dof_handler->get_fe()[cell->active_fe_index()].dofs_per_cell;
+				      * @endverbatim
+				      *
+				      * This code doesn't work in both
+				      * situations without the present
+				      * operator because
+				      * DoFHandler::get_fe() returns a
+				      * finite element, whereas
+				      * hp::DoFHandler::get_fe()
+				      * returns a collection of finite
+				      * elements that doesn't offer a
+				      * <code>dofs_per_cell</code>
+				      * member variable: one first has
+				      * to select which finite element
+				      * to work on, which is done
+				      * using the
+				      * operator[]. Fortunately,
+				      * <code>cell-@>active_fe_index()</code>
+				      * also works for non-hp classes
+				      * and simply returns zero in
+				      * that case. The present
+				      * operator[] accepts this zero
+				      * argument, by returning the
+				      * finite element with index zero
+				      * within its collection (that,
+				      * of course, consists only of
+				      * the present finite element
+				      * anyway).
+				      */
+    const FiniteElement<dim> & operator[] (const unsigned int fe_index) const;
+    
 				     /**
 				      * @name Shape function access
 				      * @{
@@ -2171,6 +2216,19 @@ class FiniteElement : public Subscriptor,
 
 //----------------------------------------------------------------------//
 
+
+template <int dim>
+inline
+const FiniteElement<dim> &
+FiniteElement<dim>::operator[] (const unsigned int fe_index) const
+{
+  Assert (fe_index == 0,
+	  ExcMessage ("A fe_index of zero is the only index allowed here"));
+  return *this;
+}
+
+
+
 template <int dim>  
 inline
 std::pair<unsigned int,unsigned int>
@@ -2183,6 +2241,8 @@ FiniteElement<dim>::system_to_component_index (const unsigned int index) const
   return system_to_component_table[index];
 }
 
+
+
 template <int dim>  
 inline
 unsigned int
@@ -2265,6 +2325,7 @@ FiniteElement<dim>::first_block_of_base (const unsigned int index) const
 }
 
 
+
 template <int dim>  
 inline
 std::pair<unsigned int,unsigned int>
@@ -2277,6 +2338,7 @@ FiniteElement<dim>::component_to_base_index (const unsigned int index) const
 }
 
 
+
 template <int dim>  
 inline
 std::pair<unsigned int,unsigned int>
@@ -2294,6 +2356,7 @@ FiniteElement<dim>::block_to_base_index (const unsigned int index) const
 }
 
 
+
 template <int dim>  
 inline
 std::pair<unsigned int,unsigned int>
@@ -2311,6 +2374,7 @@ FiniteElement<dim>::system_to_block_index (const unsigned int index) const
 }
 
 
+
 template <int dim>
 inline
 bool
@@ -2322,6 +2386,7 @@ FiniteElement<dim>::restriction_is_additive (const unsigned int index) const
 }
 
 
+
 template <int dim>
 inline
 const std::vector<bool> &
@@ -2364,6 +2429,7 @@ FiniteElement<dim>::is_primitive (const unsigned int i) const
 }
 
 
+
 template <int dim>
 inline
 bool
-- 
2.39.5