--- a/mercurial/graphmod.py	Sat May 16 07:12:12 2009 +0200
+++ b/mercurial/graphmod.py	Fri Jun 19 13:22:32 2009 +0200
@@ -6,25 +6,39 @@
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2, incorporated herein by reference.
 
-from node import nullrev
+"""supports walking the history as DAGs suitable for graphical output
+
+The most basic format we use is that of::
+
+  (id, type, data, [parentids])
+
+The node and parent ids are arbitrary integers which identify a node in the
+context of the graph returned. Type is a constant specifying the node type.
+Data depends on type.
+"""
+
+from mercurial.node import nullrev
+
+CHANGESET = 'C'
 
 def revisions(repo, start, stop):
-    """cset DAG generator yielding (rev, node, [parents]) tuples
+    """cset DAG generator yielding (id, CHANGESET, ctx, [parentids]) tuples
 
     This generator function walks through the revision history from revision
-    start to revision stop (which must be less than or equal to start).
+    start to revision stop (which must be less than or equal to start). It
+    returns a tuple for each node. The node and parent ids are arbitrary
+    integers which identify a node in the context of the graph returned.
     """
     assert start >= stop
     cur = start
     while cur >= stop:
         ctx = repo[cur]
         parents = [p.rev() for p in ctx.parents() if p.rev() != nullrev]
-        parents.sort()
-        yield (ctx, parents)
+        yield (cur, CHANGESET, ctx, sorted(parents))
         cur -= 1
 
 def filerevs(repo, path, start, stop):
-    """file cset DAG generator yielding (rev, node, [parents]) tuples
+    """file cset DAG generator yielding (id, CHANGESET, ctx, [parentids]) tuples
 
     This generator function walks through the revision history of a single
     file from revision start to revision stop (which must be less than or
@@ -35,20 +49,24 @@
     while filerev >= 0:
         fctx = repo.filectx(path, fileid=filerev)
         parents = [f.linkrev() for f in fctx.parents() if f.path() == path]
-        parents.sort()
-        if fctx.rev() <= start:
-            yield (fctx, parents)
-        if fctx.rev() <= stop:
+        rev = fctx.rev()
+        if rev <= start:
+            yield (rev, CHANGESET, fctx, sorted(parents))
+        if rev <= stop:
             break
         filerev -= 1
 
 def nodes(repo, nodes):
+    """cset DAG generator yielding (id, CHANGESET, ctx, [parentids]) tuples
+
+    This generator function walks the given nodes. It only returns parents
+    that are in nodes, too.
+    """
     include = set(nodes)
     for node in nodes:
         ctx = repo[node]
         parents = [p.rev() for p in ctx.parents() if p.node() in include]
-        parents.sort()
-        yield (ctx, parents)
+        yield (ctx.rev(), CHANGESET, ctx, sorted(parents))
 
 def graph(repo, start_rev, stop_rev):
     """incremental revision grapher