From f986b814683ddee836b534f344bca017ac697c58 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 23:55:47 +0200
Subject: [PATCH] filters: Define TaskFilter base class

---
 tasklib/filters.py | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/tasklib/filters.py b/tasklib/filters.py
index 211302f..7b44e98 100644
--- a/tasklib/filters.py
+++ b/tasklib/filters.py
@@ -1,7 +1,35 @@
+import abc
 from tasklib.serializing import SerializingObject
 
 
-class TaskWarriorFilter(SerializingObject):
+class TaskFilter(object):
+    """
+    Abstract base class that defines interface of a TaskFilter.
+    """
+
+    @abc.abstractmethod
+    def add_filter(self, arg):
+        """
+        Processes an non-keyword filter.
+        """
+        pass
+
+    @abc.abstractmethod
+    def add_filter_param(self, key, value):
+        """
+        Processes a keyword filter.
+        """
+        pass
+
+    @abc.abstractmethod
+    def clone(self):
+        """
+        Returns a new deep copy of itself.
+        """
+        pass
+
+
+class TaskWarriorFilter(TaskFilter, SerializingObject):
     """
     A set of parameters to filter the task list with.
     """
-- 
2.39.5