mpd: Add range support to 'load' command

docs/changes.rst

@@ -14,6 +14,9 @@ v0.11.0 (in development)
 
 - Add support for ``config`` command added in MPD 0.17.
 
+- Add support for loading a range of tracks from a playlist to the ``load``
+  command, as added in MPD 0.17.
+
 
 v0.10.0 (2012-12-12)
 ====================

mopidy/frontends/mpd/protocol/stored_playlists.py

@@ -92,23 +92,36 @@ def listplaylists(context):
     return result
 
 
-@handle_request(r'^load "(?P<name>[^"]+)"$')
-def load(context, name):
+@handle_request(r'^load "(?P<name>[^"]+)"( "(?P<start>\d+):(?P<end>\d+)*")*$')
+def load(context, name, start=None, end=None):
     """
     *musicpd.org, stored playlists section:*
 
-        ``load {NAME}``
+        ``load {NAME} [START:END]``
 
-        Loads the playlist ``NAME.m3u`` from the playlist directory.
+        Loads the playlist into the current queue. Playlist plugins are
+        supported. A range may be specified to load only a part of the
+        playlist.
 
     *Clarifications:*
 
     - ``load`` appends the given playlist to the current playlist.
+
+    - MPD 0.17.1 does not support open-ended ranges, i.e. without end
+      specified, for the ``load`` command, even though MPD's general range docs
+      allows open-ended ranges.
+
+    - MPD 0.17.1 does not fail if the specified range is outside the playlist,
+      in either or both ends.
     """
     playlists = context.core.playlists.filter(name=name).get()
     if not playlists:
         raise MpdNoExistError('No such playlist', command='load')
-    context.core.tracklist.add(playlists[0].tracks)
+    if start is not None:
+        start = int(start)
+    if end is not None:
+        end = int(end)
+    context.core.tracklist.add(playlists[0].tracks[start:end])
 
 
 @handle_request(r'^playlistadd "(?P<name>[^"]+)" "(?P<uri>[^"]+)"$')

tests/frontends/mpd/protocol/stored_playlists_test.py

@@ -73,7 +73,7 @@ class PlaylistsHandlerTest(protocol.BaseTestCase):
         self.assertNotInResponse('playlist: ')
         self.assertInResponse('OK')
 
-    def test_load_known_playlist_appends_to_tracklist(self):
+    def test_load_appends_to_tracklist(self):
         self.core.tracklist.add([Track(uri='a'), Track(uri='b')])
         self.assertEqual(len(self.core.tracklist.tracks.get()), 2)
         self.backend.playlists.playlists = [
@@ -81,6 +81,7 @@ class PlaylistsHandlerTest(protocol.BaseTestCase):
                 Track(uri='c'), Track(uri='d'), Track(uri='e')])]
 
         self.sendRequest('load "A-list"')
+
         tracks = self.core.tracklist.tracks.get()
         self.assertEqual(5, len(tracks))
         self.assertEqual('a', tracks[0].uri)
@@ -90,6 +91,39 @@ class PlaylistsHandlerTest(protocol.BaseTestCase):
         self.assertEqual('e', tracks[4].uri)
         self.assertInResponse('OK')
 
+    def test_load_with_range_loads_part_of_playlist(self):
+        self.core.tracklist.add([Track(uri='a'), Track(uri='b')])
+        self.assertEqual(len(self.core.tracklist.tracks.get()), 2)
+        self.backend.playlists.playlists = [
+            Playlist(name='A-list', tracks=[
+                Track(uri='c'), Track(uri='d'), Track(uri='e')])]
+
+        self.sendRequest('load "A-list" "1:2"')
+
+        tracks = self.core.tracklist.tracks.get()
+        self.assertEqual(3, len(tracks))
+        self.assertEqual('a', tracks[0].uri)
+        self.assertEqual('b', tracks[1].uri)
+        self.assertEqual('d', tracks[2].uri)
+        self.assertInResponse('OK')
+
+    def test_load_with_range_without_end_loads_rest_of_playlist(self):
+        self.core.tracklist.add([Track(uri='a'), Track(uri='b')])
+        self.assertEqual(len(self.core.tracklist.tracks.get()), 2)
+        self.backend.playlists.playlists = [
+            Playlist(name='A-list', tracks=[
+                Track(uri='c'), Track(uri='d'), Track(uri='e')])]
+
+        self.sendRequest('load "A-list" "1:"')
+
+        tracks = self.core.tracklist.tracks.get()
+        self.assertEqual(4, len(tracks))
+        self.assertEqual('a', tracks[0].uri)
+        self.assertEqual('b', tracks[1].uri)
+        self.assertEqual('d', tracks[2].uri)
+        self.assertEqual('e', tracks[3].uri)
+        self.assertInResponse('OK')
+
     def test_load_unknown_playlist_acks(self):
         self.sendRequest('load "unknown playlist"')
         self.assertEqual(0, len(self.core.tracklist.tracks.get()))