X-Git-Url: https://git.madduck.net/etc/taskwarrior.git/blobdiff_plain/ff45f9122b3f1a441491d9bcb0d9681039baea38..516b8d6c03058552cfe7c3bfda4362640a3077e1:/tasklib/filters.py

diff --git a/tasklib/filters.py b/tasklib/filters.py
index 211302f..b7cab64 100644
--- a/tasklib/filters.py
+++ b/tasklib/filters.py
@@ -1,14 +1,43 @@
-from tasklib.serializing import SerializingObject
+import abc
+import six
+from .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.
     """
 
-    def __init__(self, warrior, filter_params=None):
+    def __init__(self, backend, filter_params=None):
         self.filter_params = filter_params or []
-        super(TaskFilter, self).__init__(warrior)
+        super(TaskFilter, self).__init__(backend)
 
     def add_filter(self, filter_str):
         self.filter_params.append(filter_str)
@@ -35,7 +64,7 @@ class TaskWarriorFilter(SerializingObject):
             # We enforce equality match by using 'is' (or 'none') modifier
             # Without using this syntax, filter fails due to TW-1479
             # which is, however, fixed in 2.4.5
-            if self.warrior.version < VERSION_2_4_5:
+            if self.backend.version < self.backend.VERSION_2_4_5:
                 modifier = '.is' if value else '.none'
                 key = key + modifier if '.' not in key else key
 
@@ -45,6 +74,6 @@ class TaskWarriorFilter(SerializingObject):
         return [f for f in self.filter_params if f]
 
     def clone(self):
-        c = self.__class__(self.warrior)
+        c = self.__class__(self.backend)
         c.filter_params = list(self.filter_params)
         return c