Rev 2391: Tighten the algorithm requirements - tails are not required because the exclusion on misses will converge. Also add Nonempty to empty test. in file:///home/robertc/source/baz/netsim/

[Robert Collins]

At file:///home/robertc/source/baz/netsim/

------------------------------------------------------------
revno: 2391
revision-id: robertc at robertcollins.net-20070401063117-71od8scu0te38npy
parent: robertc at robertcollins.net-20070401061938-xzhb1m77i7fzzkb6
committer: Robert Collins <robertc at robertcollins.net>
branch nick: netsim
timestamp: Sun 2007-04-01 16:31:17 +1000
message:
  Tighten the algorithm requirements - tails are not required because the exclusion on misses will converge. Also add Nonempty to empty test.
modified:
  bzrlib/graph.py                graph.py-20050905070950-b47dce53236c5e48
  bzrlib/tests/test_graph.py     testgraph.py-20050905070950-42e6c958106610fd
  doc/design/server.txt          server.txt-20070401020531-rqa7d77i22idnj78-2
=== modified file 'bzrlib/graph.py'
--- a/bzrlib/graph.py	2007-04-01 06:19:38 +0000
+++ b/bzrlib/graph.py	2007-04-01 06:31:17 +0000
@@ -137,14 +137,6 @@
             self._ensure_descendant(parent)
             self._graph_descendants[parent][node_id] = 1
 
-    def apply_changes(self, delta):
-        """Apply a delta obtained from a changes_from call.
-
-        :return: A new graph which is the result of applying delta to this
-        graph.
-        """
-        return Graph()
-
     def changes_from(self, graph_from):
         """Create a GraphDelta from graph_from to self."""
         return GraphDelta._changes_from(graph_from, self)
@@ -185,6 +177,16 @@
     This restriction may be lifted in the future.
     """
 
+    def __eq__(self, other):
+        return isinstance(other, GraphDelta) and self.__dict__ == other.__dict__
+
+    def apply_to(self, from_):
+        """Apply this delta to the graph from_.
+        
+        :return: A new graph derived from from_ and this delta.
+        """
+        return Graph()
+
     @classmethod
     def _changes_from(cls, from_, to):
         """Construct a delta from from_ to to."""

=== modified file 'bzrlib/tests/test_graph.py'
--- a/bzrlib/tests/test_graph.py	2007-04-01 06:19:38 +0000
+++ b/bzrlib/tests/test_graph.py	2007-04-01 06:31:17 +0000
@@ -83,17 +83,33 @@
 
 class TestGraphDelta(TestCase):
 
-    def testEmptyEmptyGraph(self):
-        graph_from = Graph()
-        graph_to = Graph()
+    def check_delta(self, expected_delta, graph_from, graph_to):
+        """Check the delta from graph_from to graph_to.
+
+        This will calculate a new delta, check that applying it to graph_from
+        results in graph_to, and that it is equal to expected_delta.
+        """
         delta = graph_to.changes_from(graph_from)
         self.assertIsInstance(delta, GraphDelta)
-        new_to = graph_from.apply_changes(delta)
+        self.assertEqual(expected_delta, delta)
+        new_to = delta.apply_to(graph_from)
         self.assertEqual(graph_to, new_to)
 
+    def testEmptyEmptyGraph(self):
+        graph_from = Graph()
+        graph_to = Graph()
+        self.check_delta(GraphDelta(), graph_from, graph_to)
+
     def testTargetNotSubGraph(self):
         """When the target is not a sub-graph of the source, get an exception."""
         graph_from = Graph()
         graph_to = Graph()
         graph_to.add_node('A', [])
         self.assertRaises(NotSubGraph, graph_to.changes_from, graph_from)
+
+    def testSmallEmptyGraph(self):
+        graph_from = Graph()
+        graph_from.add_node('A', [])
+        graph_to = Graph()
+        result = GraphDelta()
+        self.check_delta(result, graph_from, graph_to)

=== modified file 'doc/design/server.txt'
--- a/doc/design/server.txt	2007-04-01 02:16:22 +0000
+++ b/doc/design/server.txt	2007-04-01 06:31:17 +0000
@@ -34,9 +34,6 @@
 have the following properties:
  * It is repeatable given the token and the graph.
  * The token must be short(< the size of a node) and serialisable.
-To prevent repeating loops it must also:
- * include all the terminal nodes of each disjoint subgraph.
-
 
 Constraints:
  * The client is permitted state.