From 14cb9090ec3ef15efd487accfc3be3346bcc4aee Mon Sep 17 00:00:00 2001
From: Matthias Koefferlein <matthias@koefferlein.de>
Date: Tue, 8 Jan 2019 21:53:10 +0100
Subject: [PATCH] Provide operator-- on SortedCellIndexIterator to fix #220

---
 src/db/db/dbCellMapping.cc | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/db/db/dbCellMapping.cc b/src/db/db/dbCellMapping.cc
index 8888a9ebf..66490629d 100644
--- a/src/db/db/dbCellMapping.cc
+++ b/src/db/db/dbCellMapping.cc
@@ -72,13 +72,25 @@ struct SortedCellIndexIterator
   SortedCellIndexIterator &operator++() 
   {
     ++m_n;
-	return *this;
+    return *this;
   }
 
   SortedCellIndexIterator &operator+=(size_t n) 
   {
     m_n += n;
-	return *this;
+    return *this;
+  }
+
+  SortedCellIndexIterator &operator--()
+  {
+    --m_n;
+    return *this;
+  }
+
+  SortedCellIndexIterator &operator-=(size_t n)
+  {
+    m_n -= n;
+    return *this;
   }
 
   bool operator==(const SortedCellIndexIterator &d) const