lib: Give Tags an ability to loop during next()

I also provide a can_loop() function that the UI can use to determine
activatability of the loop toogle button.

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

lib/tag.py

@@ -7,6 +7,7 @@ class Tag:
         self.name = name
         self.sort = sort.lower() if sort else str(name).lower()
         self.current = -1
+        self.loop = False
         self.tracks = [ ]
         self.widgets = None
         self.lock = threading.Lock()
@@ -18,6 +19,7 @@ class Tag:
             return { "name"    : self.name,
                      "sort"    : self.sort,
                      "current" : self.current,
+                     "loop"    : self.loop,
                      "tracks"  : [ t.trackid for t in self.tracks ] }
 
     def __len__(self):
@@ -31,10 +33,16 @@ class Tag:
             return True
         return self.sort < rhs.parent.sort
 
+    def __next_track__(self):
+        if self.loop == True and self.current >= len(self.tracks):
+            return 0
+        return self.current + 1
+
     def __setstate__(self, state):
         self.name    = state["name"]
         self.sort    = state["sort"]
         self.current = state["current"]
+        self.loop    = state["loop"]
         self.tracks  = state["tracks"]
         self.widgets = None
         self.lock    = threading.Lock()
@@ -49,6 +57,8 @@ class Tag:
             self.tracks.append(track)
         self.TrackAdded.publish(self, track)
 
+    def can_loop(self): return True
+
     def get_header(self):
         return self.sort[0].upper() if len(self.sort) > 0 else ""
 
@@ -62,7 +72,7 @@ class Tag:
 
     def next(self):
         with self.lock:
-            self.current += 1
+            self.current = self.__next_track__()
             if self.current < len(self.tracks):
                 return self.tracks[self.current]
             return None
@@ -79,12 +89,9 @@ class SuperTag(Tag):
         self.parent = parent
 
     def __getstate__(self):
-        with self.lock:
-            return { "name"    : self.name,
-                     "sort"    : self.sort,
-                     "current" : self.current,
-                     "tracks"  : [ t.trackid for t in self.tracks ],
-                     "parent" : self.parent }
+        state = Tag.__getstate__(self)
+        state["parent"] = self.parent
+        return state
 
     def __lt__(self, rhs):
         if not isinstance(rhs, SuperTag):

lib/test_tag.py

@@ -22,6 +22,8 @@ class TestTag(unittest.TestCase):
         self.assertEqual(t.sort, "test")
         self.assertEqual(t.current, -1)
         self.assertEqual(t.tracks, [ ])
+        self.assertFalse(t.loop)
+        self.assertTrue( t.can_loop())
         self.assertIsNone(t.widgets)
         self.assertIsInstance(t.lock, type(threading.Lock()))
         self.assertIsInstance(t.TrackAdded, publisher.Publisher)
@@ -61,11 +63,12 @@ class TestTag(unittest.TestCase):
 
         state = t.__getstate__()
         self.assertEqual(set(state.keys()),
-                set([ "name", "sort", "current", "tracks" ]))
+                set([ "name", "sort", "current", "loop", "tracks" ]))
         self.assertEqual(state["name"], "test")
         self.assertEqual(state["sort"], "test")
         self.assertEqual(state["current"], -1)
         self.assertEqual(state["tracks"], [ 0, 1, 2, 3, 4 ])
+        self.assertFalse(state["loop"])
 
         state["sort"] = "sort"
         state["current"] = 42
@@ -77,6 +80,7 @@ class TestTag(unittest.TestCase):
         self.assertEqual(t.current, 42)
         self.assertEqual(t.tracks, [ 0, 1, 2, 3, 4 ])
         self.assertEqual(t.widgets, None)
+        self.assertFalse(t.loop)
         self.assertIsInstance(t.lock, type(threading.Lock()))
         self.assertIsInstance(t.TrackAdded, publisher.Publisher)
         self.assertIsInstance(t.TrackRemoved, publisher.Publisher)
@@ -126,6 +130,10 @@ class TestTag(unittest.TestCase):
         self.assertIsNone(t.next())
         self.assertEqual(t.current, 3)
 
+        t.loop = True
+        self.assertEqual(t.next(), 1)
+        self.assertEqual(t.current, 0)
+
 
 class TestSuperTag(unittest.TestCase):
     def test_super_tag(self):