symuid-list: refactor (use generators)

symuid-list

@@ -4,20 +4,20 @@
 import symuid
 
 
+def walk_attr(root_path, path_ignore_regex):
+    for track in symuid.Track.walk(root_path, path_ignore_regex):
+        yield {'path': track.path, 'play_count': track.get_play_count_sum()}
+
+
 def symuid_list(path, path_ignore_regex, filter_expression, sort_expression):
-    selection = []
-    for track in symuid.Track.walk(root_path=path, path_ignore_regex=path_ignore_regex):
-        if filter_expression or sort_expression:
-            track_attr = {'path': track.path, 'play_count': track.get_play_count_sum()}
-        if not filter_expression or eval(filter_expression, track_attr):
-            if sort_expression:
-                selection.append((eval(sort_expression, track_attr), track.path))
-            else:
-                print(track.path)
+    attr_it = walk_attr(path, path_ignore_regex)
+    if filter_expression:
+        attr_it = filter(lambda a: eval(filter_expression, a), attr_it)
     if sort_expression:
-        selection.sort()
-        for sort_key, track_path in selection:
-            print(track_path)
+        attr_it = list(attr_it)
+        attr_it.sort(key=lambda a: eval(sort_expression, a))
+    for attr in attr_it:
+        print(attr['path'])
 
 
 def _init_argparser():