From 829966d9a155762de06d1580388909ee742fe840 Mon Sep 17 00:00:00 2001
From: Matthias Koefferlein <matthias@koefferlein.de>
Date: Sat, 7 Apr 2018 09:21:50 +0200
Subject: [PATCH] Fixed #108 (Box#enlarge, Box#move on empty boxes)

---
 src/db/db/dbBox.h          | 12 ++++++++----
 src/db/unit_tests/dbBox.cc |  7 +++++++
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/src/db/db/dbBox.h b/src/db/db/dbBox.h
index ea3e1648e..a3319fffb 100644
--- a/src/db/db/dbBox.h
+++ b/src/db/db/dbBox.h
@@ -860,8 +860,10 @@ template <class C, class R>
 inline box<C, R> &
 box<C, R>::move (const vector<C> &p)
 {
-  m_p1 += p;
-  m_p2 += p;
+  if (! empty ()) {
+    m_p1 += p;
+    m_p2 += p;
+  }
   return *this;
 }
 
@@ -869,8 +871,10 @@ template <class C, class R>
 inline box<C, R> &
 box<C, R>::enlarge (const vector<C> &p)
 {
-  m_p1 -= p;
-  m_p2 += p;
+  if (! empty ()) {
+    m_p1 -= p;
+    m_p2 += p;
+  }
   return *this;
 }
 
diff --git a/src/db/unit_tests/dbBox.cc b/src/db/unit_tests/dbBox.cc
index 071d04ab5..5a3396c7b 100644
--- a/src/db/unit_tests/dbBox.cc
+++ b/src/db/unit_tests/dbBox.cc
@@ -41,12 +41,19 @@ TEST(2)
 
   EXPECT_EQ (b.moved (db::Vector (10, 20)), db::Box (110, 20, 10, 220));
   EXPECT_EQ (b.enlarged (db::Vector (10, 20)), db::Box (-10, -20, 110, 220));
+  EXPECT_EQ (empty.moved (db::Vector (10, 20)).empty (), true);
+  EXPECT_EQ (empty.enlarged (db::Vector (10, 20)).empty (), true);
   EXPECT_EQ (b + db::Box (-10, 20, 100, 200), db::Box (-10, 0, 100, 200));
   EXPECT_EQ (b + db::Box (-10, -20, 100, -10), db::Box (-10, -20, 100, 200));
   EXPECT_EQ (b + db::Box (110, 220, 120, 250), db::Box (0, 0, 120, 250));
   EXPECT_EQ (b & db::Box (110, 220, 120, 250), empty);
   EXPECT_EQ (b & db::Box (50, 100, 120, 250), db::Box (50, 100, 100, 200));
   EXPECT_EQ (b & db::Box (50, 100, 60, 120), db::Box (50, 100, 60, 120));
+
+  empty.move (db::Vector (10, 20));
+  EXPECT_EQ (empty == db::Box (), true);
+  empty.enlarge (db::Vector (10, 20));
+  EXPECT_EQ (empty == db::Box (), true);
 }
 
 TEST(3)