From 46ead34f45e6926070de8813e5a35cb5b6dcdbd7 Mon Sep 17 00:00:00 2001
From: Niels Serup <ns@metanohi.name>
Date: Tue, 14 Aug 2012 17:02:06 +0200
Subject: [PATCH] Fixed critical infinite loop bug in teleportermap.

---
 robotgame/logic/direction.py     |  2 +-
 robotgame/logic/teleportermap.py | 25 +++++++++++++++++++++----
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/robotgame/logic/direction.py b/robotgame/logic/direction.py
index 1107bcf..78a96db 100644
--- a/robotgame/logic/direction.py
+++ b/robotgame/logic/direction.py
@@ -80,7 +80,7 @@ class Left(Direction):
     def to_str():
         return 'left'
 
-all_directions = (Up, Right, Down, Left)
+all_directions = [Up, Right, Down, Left]
 _sp = lambda n: lambda d: all_directions[(all_directions.index(d) + n) % 4]
 succ, pred = _sp(1), _sp(-1)
 isDirection = all_directions.__contains__
diff --git a/robotgame/logic/teleportermap.py b/robotgame/logic/teleportermap.py
index 7043917..573678c 100644
--- a/robotgame/logic/teleportermap.py
+++ b/robotgame/logic/teleportermap.py
@@ -41,6 +41,9 @@ class Empty(object):
 class Forbidden(object):
     pass
 
+class StrictlyForbidden(object):
+    pass
+
 class Visited(object):
     pass
 
@@ -50,7 +53,7 @@ def generate_teleporter_map(width, height):
 
     def _get(p):
         if p[0] < 0 or p[0] >= width or p[1] < 0 or p[1] >= height:
-            return Forbidden
+            return StrictlyForbidden
         return m[p[0]][p[1]]
 
     def _set(p, val):
@@ -72,8 +75,12 @@ def generate_teleporter_map(width, height):
         while True:
             if pos[0] == 1 and random.randint(0, height) == 0:
                 break
-            t, found = random.randrange(4), None
-            for direc in all_directions[t:] + all_directions[:t]:
+            t = random.randrange(4)
+            found = None
+            alldirs = all_directions
+            if random.choice((True, False)):
+                alldirs.reverse()
+            for direc in alldirs[t:] + alldirs[:t]:
                 npos = direc.next_pos(pos)
                 if found is None and npos[0] != 0 and _get(npos) is Empty and (
                     (direc is Right and
@@ -92,12 +99,21 @@ def generate_teleporter_map(width, height):
             pos = found
         if pos[0] == 1:
             break
-        _set(pos, Forbidden)
+
+        _set(pos, StrictlyForbidden)
         for direc in all_directions:
             npos = direc.next_pos(pos)
             if _get(npos) is Visited:
                 pos = npos
                 break
+        for direc in all_directions:
+            npos = direc.next_pos(pos)
+            if _get(npos) is Forbidden:
+                occup_direc = succ(succ(direc))
+                if all(ndirec is occup_direc
+                       or _get(ndirec.next_pos(npos)) in (Forbidden, Empty)
+                       for ndirec in all_directions):
+                    _set(npos, Empty)
         
     _set((0, pos[1]), Visited)
     return m
@@ -121,6 +137,7 @@ def print_map(tmap):
             c = tmap[x][y]
             print({Empty: '%',
                    Forbidden: '#',
+                   StrictlyForbidden: '!',
                    Visited: '·'}[c], end='')
         print()