lib: Create a new Filter class

The intention is to have some common code that can be shared by both the
sidebar and the tracklist so they don't need to re-implement the same
things.

Implements: #4 (Create common filtering widgets)
Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

lib/__init__.py

@@ -5,6 +5,7 @@ gi.require_version("Gst", "1.0")
 
 from . import bus
 from . import data
+from . import filter
 from . import publisher
 from . import settings
 from . import tag

lib/filter.py

@@ -0,0 +1,24 @@
+# Copyright 2021 (c) Anna Schumaker.
+import re
+from gi.repository import Gtk
+
+class Regex(Gtk.Filter):
+    def __init__(self):
+        Gtk.Filter.__init__(self)
+        self.pattern = re.compile("")
+
+    def do_match(self, item):
+        raise NotImplementedError
+
+    def search(self, text):
+        return self.pattern.search(text) != None
+
+    def set_pattern(self, pattern):
+        change = Gtk.FilterChange.DIFFERENT
+        if pattern in self.pattern.pattern:
+            change = Gtk.FilterChange.LESS_STRICT
+        elif self.pattern.pattern in pattern:
+            change = Gtk.FilterChange.MORE_STRICT
+
+        self.pattern = re.compile(pattern, re.I)
+        self.changed(change)

lib/test_filter.py

@@ -0,0 +1,40 @@
+# Copyright 2021 (c) Anna Schumaker.
+import lib
+import re
+import unittest
+from gi.repository import Gtk
+
+class TestRegex(unittest.TestCase):
+    def changed(self, filter, how):
+        self.how = how
+
+    def test_init(self):
+        filter = lib.filter.Regex()
+        self.assertIsInstance(filter, Gtk.Filter)
+        self.assertIsInstance(filter.pattern, re.Pattern)
+        self.assertEqual(filter.pattern.pattern, "")
+        with self.assertRaises(NotImplementedError):
+            filter.do_match(None)
+
+    def test_set_pattern(self):
+        filter = lib.filter.Regex()
+        filter.connect("changed", self.changed)
+
+        filter.set_pattern("abc")
+        self.assertEqual(filter.pattern.pattern, "abc")
+        self.assertEqual(self.how, Gtk.FilterChange.MORE_STRICT)
+
+        filter.set_pattern("ab")
+        self.assertEqual(filter.pattern.pattern, "ab")
+        self.assertEqual(self.how, Gtk.FilterChange.LESS_STRICT)
+
+        filter.set_pattern("cd")
+        self.assertEqual(self.how, Gtk.FilterChange.DIFFERENT)
+        self.assertEqual(filter.pattern.pattern, "cd")
+
+    def test_search(self):
+        filter = lib.filter.Regex()
+        filter.set_pattern("ab")
+
+        self.assertTrue(filter.search("abc"))
+        self.assertFalse(filter.search("cde"))