playlist: Create a custom filter for matching tracks

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

playlist/filter.py

@@ -0,0 +1,28 @@
+# Copyright 2021 (c) Anna Schumaker.
+from gi.repository import Gtk
+import re
+
+class Filter(Gtk.CustomFilter):
+    def __init__(self):
+        Gtk.CustomFilter.__init__(self)
+        self.text = None
+        self.pattern = re.compile("")
+
+        self.set_filter_func(self.filter_func)
+
+    def filter_func(self, track):
+        for field in [ "artist", "album", "title" ]:
+            if self.pattern.search(track[field]) != None:
+                return True
+        return False
+
+    def set_search_text(self, text):
+        change = Gtk.FilterChange.DIFFERENT
+        if self.text == None or self.text in text:
+            Gtk.FilterChange.MORE_STRICT
+        elif text in self.text:
+            Gtk.FilterChange.LESS_STRICT
+
+        self.pattern = re.compile(text, re.I)
+        self.text = text
+        self.changed(change)

playlist/test_filter.py

@@ -0,0 +1,15 @@
+# Copyright 2021 (c) Anna Schumaker.
+from . import filter
+from gi.repository import Gtk
+import unittest
+
+class TestPlaylistFilter(unittest.TestCase):
+    def test_playlist_filter_init(self):
+        f = filter.Filter()
+        self.assertIsInstance(f, Gtk.CustomFilter)
+        self.assertIsNone(f.text)
+        self.assertEqual(f.pattern.pattern, "")
+
+        f.set_search_text("text")
+        self.assertEqual(f.text, "text")
+        self.assertEqual(f.pattern.pattern, "text")