From: Martin Kronbichler <kronbichler@lnm.mw.tum.de>
Date: Sat, 22 Nov 2014 07:08:33 +0000 (+0100)
Subject: Improved comparison operators for TriaAccessorBase
X-Git-Tag: v8.2.0-rc1~49^2~1
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c07e2596b5fb3297ad3ad6b426f6d17acfa462c2;p=dealii.git

Improved comparison operators for TriaAccessorBase

The previous commit was a bit too aggressive because it is still useful to catch the case when comparing iterators to two different triangulations (leading to infinite loops).

Therefore, I now merely extended the assertion to not trigger when one of the two objects is default constructed, i.e., does contain a null pointer to tria. The comparison then does not need tria == a.tria because invalid iterators use invalid cell and level index, too (leading to !=).
---

diff --git a/include/deal.II/grid/tria_accessor.templates.h b/include/deal.II/grid/tria_accessor.templates.h
index 97232e4268..9781cc01da 100644
--- a/include/deal.II/grid/tria_accessor.templates.h
+++ b/include/deal.II/grid/tria_accessor.templates.h
@@ -121,8 +121,9 @@ inline
 bool
 TriaAccessorBase<structdim,dim,spacedim>::operator == (const TriaAccessorBase<structdim,dim,spacedim> &a) const
 {
-  return ((tria == a.tria) &&
-          (present_level == a.present_level) &&
+  Assert (tria == a.tria || tria == 0 || a.tria == 0,
+          TriaAccessorExceptions::ExcCantCompareIterators());
+  return ((present_level == a.present_level) &&
           (present_index == a.present_index));
 }
 
@@ -133,8 +134,9 @@ inline
 bool
 TriaAccessorBase<structdim,dim,spacedim>::operator != (const TriaAccessorBase<structdim,dim,spacedim> &a) const
 {
-  return ((tria != a.tria) ||
-          (present_level != a.present_level) ||
+  Assert (tria == a.tria || tria == 0 || a.tria == 0,
+          TriaAccessorExceptions::ExcCantCompareIterators());
+  return ((present_level != a.present_level) ||
           (present_index != a.present_index));
 }