Add index() method to CurrentPlaylistController to reduce copying of the playlist

docs/changes.rst

@@ -18,13 +18,14 @@ v0.7.0 (in development)
   if you use playlist folders, you will no longer get lots of log messages
   about bad playlists.
 
+- The MPD command ``playlistinfo`` is now faster, thanks to John Bäckstrand.
+
 - Added the method
-  :meth:`mopidy.backends.base.CurrentPlaylistController.length()` to reduce the
+  :meth:`mopidy.backends.base.CurrentPlaylistController.length()` and
+  :meth:`mopidy.backends.base.CurrentPlaylistController.index()` to reduce the
   need for copying the entire current playlist from one thread to another.
   Thanks to John Bäckstrand.
 
-- The MPD command ``playlistinfo`` is now faster, thanks to John Bäckstrand.
-
 
 v0.6.0 (2011-10-09)
 ===================

mopidy/backends/base/current_playlist.py

@@ -136,6 +136,19 @@ class CurrentPlaylistController(object):
         else:
             raise LookupError(u'"%s" match multiple tracks' % criteria_string)
 
+    def index(self, cp_track):
+        """
+        Get index of the given (CPID integer, :class:`mopidy.models.Track`)
+        two-tuple in the current playlist.
+
+        Raises :exc:`ValueError` if not found.
+
+        :param cp_track: track to find the index of
+        :type cp_track: two-tuple (CPID integer, :class:`mopidy.models.Track`)
+        :rtype: int
+        """
+        return self._cp_tracks.index(cp_track)
+
     def move(self, start, end, to_position):
         """
         Move the tracks in the slice ``[start:end]`` to ``to_position``.
@@ -175,7 +188,6 @@ class CurrentPlaylistController(object):
 
         :param criteria: on or more criteria to match by
         :type criteria: dict
-        :type track: :class:`mopidy.models.Track`
         """
         cp_track = self.get(**criteria)
         position = self._cp_tracks.index(cp_track)

mopidy/frontends/mpd/protocol/current_playlist.py

@@ -158,8 +158,7 @@ def moveid(context, cpid, to):
     cpid = int(cpid)
     to = int(to)
     cp_track = context.backend.current_playlist.get(cpid=cpid).get()
-    position = context.backend.current_playlist.cp_tracks.get().index(
+    position = context.backend.current_playlist.index(cp_track).get()
-        cp_track)
     context.backend.current_playlist.move(position, position + 1, to)
 
 @handle_request(r'^playlist$')
@@ -194,8 +193,7 @@ def playlistfind(context, tag, needle):
     if tag == 'filename':
         try:
             cp_track = context.backend.current_playlist.get(uri=needle).get()
-            position = context.backend.current_playlist.cp_tracks.get().index(
+            position = context.backend.current_playlist.index(cp_track).get()
-                cp_track)
             return track_to_mpd_format(cp_track, position=position)
         except LookupError:
             return None
@@ -215,8 +213,7 @@ def playlistid(context, cpid=None):
         try:
             cpid = int(cpid)
             cp_track = context.backend.current_playlist.get(cpid=cpid).get()
-            position = context.backend.current_playlist.cp_tracks.get().index(
+            position = context.backend.current_playlist.index(cp_track).get()
-                cp_track)
             return track_to_mpd_format(cp_track, position=position)
         except LookupError:
             raise MpdNoExistError(u'No such song', command=u'playlistid')
@@ -375,7 +372,6 @@ def swapid(context, cpid1, cpid2):
     cpid2 = int(cpid2)
     cp_track1 = context.backend.current_playlist.get(cpid=cpid1).get()
     cp_track2 = context.backend.current_playlist.get(cpid=cpid2).get()
-    cp_tracks = context.backend.current_playlist.cp_tracks.get()
+    position1 = context.backend.current_playlist.index(cp_track1).get()
-    position1 = cp_tracks.index(cp_track1)
+    position2 = context.backend.current_playlist.index(cp_track2).get()
-    position2 = cp_tracks.index(cp_track2)
     swap(context, position1, position2)

tests/backends/base/current_playlist.py

@@ -1,7 +1,7 @@
 import mock
 import random
 
-from mopidy.models import Playlist, Track
+from mopidy.models import CpTrack, Playlist, Track
 from mopidy.gstreamer import GStreamer
 
 from tests.backends.base import populate_playlist
@@ -143,6 +143,18 @@ class CurrentPlaylistControllerTest(object):
         self.assertEqual(self.playback.state, self.playback.STOPPED)
         self.assertEqual(self.playback.current_track, None)
 
+    def test_index_returns_index_of_track(self):
+        cp_tracks = []
+        for track in self.tracks:
+            cp_tracks.append(self.controller.add(track))
+        self.assertEquals(0, self.controller.index(cp_tracks[0]))
+        self.assertEquals(1, self.controller.index(cp_tracks[1]))
+        self.assertEquals(2, self.controller.index(cp_tracks[2]))
+
+    def test_index_raises_value_error_if_item_not_found(self):
+        test = lambda: self.controller.index(CpTrack(0, Track()))
+        self.assertRaises(ValueError, test)
+
     @populate_playlist
     def test_move_single(self):
         self.controller.move(0, 0, 2)