Add views based on a todo list.

A view is a subset of the todo list where sorters and filters may be
applied.

Config.py

@@ -10,3 +10,5 @@ COMPLETED_FILENAME = 'done.txt'
 TAG_START = 't'
 TAG_DUE = 'due'
 TAG_STAR = 'star'
+
+SORT_STRING = 'desc:importance,due,desc:priority'

Main.py

@@ -5,6 +5,8 @@ import re
 import sys
 
 import Config
+import Filter
+import Sorter
 import TodoFile
 import TodoList
 
@@ -73,9 +75,15 @@ class Application(object):
             else:
                 error("Invalid priority given.")
 
-    def list(self):
-        print self.todolist
-        # TODO: sort + filter
+    def list(self, p_expression=None):
+        sorter = Sorter.Sorter(Config.SORT_STRING)
+
+        filters = [Filter.RelevanceFilter()]
+
+        if p_expression:
+            filters.append(Filter.GrepFilter(p_expression))
+
+        print self.todolist.view(sorter, filters)
 
     def run(self):
         """ Main entry function. """

TodoList.py

@@ -5,6 +5,7 @@ A list of todo items.
 import re
 
 import Todo
+import View
 
 class TodoList(object):
     """
@@ -87,7 +88,7 @@ class TodoList(object):
 
         return result
 
-    def view(self, p_sorter, p_filter):
+    def view(self, p_sorter, p_filters):
         """
         Constructs a view of the todo list.
 
@@ -95,8 +96,7 @@ class TodoList(object):
         defined by the end user. Todos is this list should not be modified,
         modifications should occur through this class.
         """
-        # TODO: perhaps change list such that values are immutable?
-        return p_filter.filter(p_sorter.sort(self._todos))
+        return View.View(p_sorter, p_filters, self._todos)
 
     def __str__(self):
         return '\n'.join([str(x) for x in self._todos])

View.py

+class View:
+    def __init__(self, p_sorter, p_filters, p_todos):
+        self._todos = p_todos
+        self._viewdata = []
+        self._sorter = p_sorter
+        self._filters = p_filters
+
+        self.update()
+
+    def update(self):
+        """
+        Updates the view data. Should be called when the backing todo list
+        has changed.
+        """
+        self._viewdata = self._sorter.sort(self._todos)
+
+        for _filter in self._filters:
+            self._viewdata = _filter.filter(self._viewdata)
+
+    def __str__(self):
+        return '\n'.join([str(x) for x in self._viewdata])