# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@octobus.net>
# Date 1669646931 -3600
# Node ID 191f5057ec45830e8d02ecf749d84bc1029ef3c5
# Parent  4bd12c0f531e8b15db2d7ff6d720374aea081706
emitrevision: add a small closure to check if a base is usable

We will make more use of this and make it more complex too.

diff -r 4bd12c0f531e -r 191f5057ec45 mercurial/utils/storageutil.py
--- a/mercurial/utils/storageutil.py	Mon Oct 17 16:26:16 2022 +0200
+++ b/mercurial/utils/storageutil.py	Mon Nov 28 15:48:51 2022 +0100
@@ -396,6 +396,9 @@
     # Set of revs available to delta against.
     available = set()
 
+    def is_usable_base(rev):
+        return rev != nullrev and rev in available
+
     for rev in revs:
         if rev == nullrev:
             continue
@@ -445,7 +448,7 @@
         elif deltaparentrev != nullrev:
             # Base revision was already emitted in this group. We can
             # always safely use the delta.
-            if deltaparentrev in available:
+            if is_usable_base(deltaparentrev):
                 if debug_info is not None:
                     debug_delta_source = "storage"
                 baserev = deltaparentrev