# HG changeset patch
# User Paul Morelle <paul.morelle@octobus.net>
# Date 2018-07-20 11:32:17
# Node ID f8db458651c8a1209715e3541f47fb156224ca5a
# Parent  1464183343b31158ef47ae5364ab8e81ce471368

revlog: add a method to tells whether rev is stored as a snapshot

For now we only have one type of snapshot: full snapshot versus nullrev.
However we are looking into adding intermediate snapshot where a large diff
against another snapshot is performed instead of storing a full new text.

The conditional is a bit strange and is done in order to help readability of a
some later changesets.

diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -2095,6 +2095,16 @@ class revlog(object):
         else:
             return rev - 1
 
+    def issnapshot(self, rev):
+        """tells whether rev is a snapshot
+        """
+        if rev == nullrev:
+            return True
+        deltap = self.deltaparent(rev)
+        if deltap == nullrev:
+            return True
+        return False
+
     def revdiff(self, rev1, rev2):
         """return or calculate a delta between two revisions