From patchwork Thu Feb  6 18:02:40 2014
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Subject: [2,of,4] revset: added lazyset implementation to branch revset
From: Lucas Moscovicz <lmoscovicz@fb.com>
X-Patchwork-Id: 3493
Message-Id: <464c7b677edfed6f7d00.1391709760@dev1037.prn2.facebook.com>
To: mercurial-devel@selenic.com
Date: Thu, 06 Feb 2014 10:02:40 -0800

# HG changeset patch
# User Lucas Moscovicz <lmoscovicz@fb.com>
# Date 1391645523 28800
#      Wed Feb 05 16:12:03 2014 -0800
# Node ID 464c7b677edfed6f7d00199a08c8dd7e32e72bca
# Parent  ebd119f34a845b1a92462291e025879f80f4b2e7
revset: added lazyset implementation to branch revset

Performance Benchmarking:

$ time hg log -l1 -qr "branch(default)"
0:9117c6561b0b

real  0m3.366s
user  0m3.217s
sys 0m0.095s

$ time ./hg log -l1 -qr "branch(default)"
0:9117c6561b0b

real  0m0.389s
user  0m0.199s
sys 0m0.061s

diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -444,16 +444,16 @@
             # note: falls through to the revspec case if no branch with
             # this name exists
             if pattern in repo.branchmap():
-                return baseset([r for r in subset if matcher(repo[r].branch())])
+                return lazyset(subset, lambda r: matcher(repo[r].branch()))
         else:
-            return baseset([r for r in subset if matcher(repo[r].branch())])
+            return lazyset(subset, lambda r: matcher(repo[r].branch()))
 
     s = getset(repo, baseset(repo), x)
     b = set()
     for r in s:
         b.add(repo[r].branch())
     s = s.set()
-    return baseset([r for r in subset if r in s or repo[r].branch() in b])
+    return lazyset(subset, lambda r: r in s or repo[r].branch() in b)
 
 def bumped(repo, subset, x):
     """``bumped()``