Common prefix elimination for episode titles

This should improve the amount of useful information
in episode lists, especially on mobile devices.

src/gpodder/gtkui/model.py

@@ -221,17 +221,18 @@ def get_search_term(self):
         return self._search_term
 
     def _format_description(self, episode, include_description=False):
+        title = episode.trimmed_title
         a, b = '', ''
         if episode.state != gpodder.STATE_DELETED and episode.is_new:
             a, b = '<b>', '</b>'
         if include_description and self._all_episodes_view:
-            return '%s%s%s\n<small>%s</small>' % (a, cgi.escape(episode.title), b,
+            return '%s%s%s\n<small>%s</small>' % (a, cgi.escape(title), b,
                     _('from %s') % cgi.escape(episode.channel.title))
         elif include_description:
-            return '%s%s%s\n<small>%s</small>' % (a, cgi.escape(episode.title), b,
+            return '%s%s%s\n<small>%s</small>' % (a, cgi.escape(title), b,
                     cgi.escape(episode.one_line_description()))
         else:
-            return ''.join((a, cgi.escape(episode.title), b))
+            return ''.join((a, cgi.escape(title), b))
 
     def replace_from_channel(self, channel, include_description=False,
             treeview=None):

src/gpodder/model.py

@@ -348,6 +348,15 @@ def channel(self):
     def db(self):
         return self.parent.parent.db
 
+    @property
+    def trimmed_title(self):
+        """Return the title with the common prefix trimmed"""
+        if (self.parent._common_prefix is not None and
+                self.title.startswith(self.parent._common_prefix)):
+            return self.title[len(self.parent._common_prefix):]
+
+        return self.title
+
     def _set_download_task(self, download_task):
         self.children = (download_task, self.children[1])
 
@@ -715,7 +724,7 @@ def update_from(self, episode):
 
 
 class PodcastChannel(PodcastModelObject):
-    __slots__ = schema.PodcastColumns
+    __slots__ = schema.PodcastColumns + ('_common_prefix',)
 
     UNICODE_TRANSLATE = {ord(u'ö'): u'o', ord(u'ä'): u'a', ord(u'ü'): u'u'}
 
@@ -747,6 +756,7 @@ def __init__(self, model):
         self.pause_subscription = False
 
         self.section = _('Other')
+        self._common_prefix = None
 
     @property
     def model(self):
@@ -1213,6 +1223,14 @@ def get_downloaded_episodes(self):
     def get_all_episodes(self):
         if self.children is None:
             self.children = self.db.load_episodes(self, self.episode_factory)
+
+            prefix = os.path.commonprefix([x.title for x in self.children])
+            # The common prefix must end with a space - otherwise it's not
+            # on a word boundary, and we might end up chopping off too much
+            if prefix and prefix[-1] != ' ' and ' ' in prefix:
+                prefix = prefix[:prefix.rfind(' ')+1]
+            self._common_prefix = prefix
+
         return self.children
 
     def find_unique_folder_name(self, download_folder):

src/gpodder/qmlui/model.py

@@ -96,7 +96,7 @@ def _podcast(self):
     qpodcast = Property(QObject, _podcast, notify=never_changed)
 
     def _title(self):
-        return convert(self._episode.title)
+        return convert(self._episode.trimmed_title)
 
     qtitle = Property(unicode, _title, notify=changed)