Add AndFilter, OrFilter and NotFilter for composing more complex filters.

Still needs some mechanism to easily compose filter expressions
defined by the user.

lib/Filter.py

@@ -27,6 +27,29 @@ class Filter(object):
         """ Default match value. """
         return True
 
+class NegationFilter(Filter):
+    def __init__(self, p_filter):
+        self._filter = p_filter
+
+    def match(self, p_todo):
+        return not self._filter.match(p_todo)
+
+class AndFilter(Filter):
+    def __init__(self, p_filter1, p_filter2):
+        self._filter1 = p_filter1
+        self._filter2 = p_filter2
+
+    def match(self, p_todo):
+        return self._filter1.match(p_todo) and self._filter2.match(p_todo)
+
+class OrFilter(Filter):
+    def __init__(self, p_filter1, p_filter2):
+        self._filter1 = p_filter1
+        self._filter2 = p_filter2
+
+    def match(self, p_todo):
+        return self._filter1.match(p_todo) or self._filter2.match(p_todo)
+
 class GrepFilter(Filter):
     """ Matches when the todo text contains a text. """
 

test/FilterTest.py

@@ -149,3 +149,37 @@ class FilterTest(unittest.TestCase):
         filtered_todos = limit_filter.filter(todos)
 
         self.assertEquals(len(filtered_todos), 4)
+
+    def test_filter16(self):
+        todos = load_file('data/FilterTest1.txt')
+        grep = Filter.NegationFilter(Filter.GrepFilter('+project'))
+
+        filtered_todos = grep.filter(todos)
+        reference = load_file('data/FilterTest3-result.txt')
+
+        self.assertEquals(todolist_to_string(filtered_todos), \
+            todolist_to_string(reference))
+
+    def test_filter17(self):
+        todos = load_file('data/FilterTest1.txt')
+        grep1 = Filter.GrepFilter('task')
+        grep2 = Filter.GrepFilter('project')
+        andfilter = Filter.AndFilter(grep1, grep2)
+
+        filtered_todos = andfilter.filter(todos)
+        reference = load_file('data/FilterTest4-result.txt')
+
+        self.assertEquals(todolist_to_string(filtered_todos), \
+            todolist_to_string(reference))
+
+    def test_filter18(self):
+        todos = load_file('data/FilterTest1.txt')
+        grep1 = Filter.GrepFilter('part')
+        grep2 = Filter.GrepFilter('important')
+        grep = Filter.OrFilter(grep1, grep2)
+
+        filtered_todos = grep.filter(todos)
+        reference = load_file('data/FilterTest5-result.txt')
+
+        self.assertEquals(todolist_to_string(filtered_todos), \
+            todolist_to_string(reference))

test/data/FilterTest3-result.txt

+(D) Just an arbitrary task

test/data/FilterTest4-result.txt

+(C) Another mildly important task for the +Project

test/data/FilterTest5-result.txt

+(C) This is part of some +Project
+(C) Another mildly important task for the +Project