From patchwork Fri May 29 14:38:05 2015
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Subject: [2, of, 5] revset: make internal _list() expression remove duplicated
 revisions
From: Yuya Nishihara <yuya@tcha.org>
X-Patchwork-Id: 9357
Message-Id: <5be635444c0156a6d068.1432910285@mimosa>
To: mercurial-devel@selenic.com
Date: Fri, 29 May 2015 23:38:05 +0900

# HG changeset patch
# User Yuya Nishihara <yuya@tcha.org>
# Date 1432446581 -32400
#      Sun May 24 14:49:41 2015 +0900
# Node ID 5be635444c0156a6d0688d5ba3688a9a9db7f561
# Parent  5617fab1b1f1905663bd38053144a93a746f34db
revset: make internal _list() expression remove duplicated revisions

This allows us to optimize chained 'or' operations to _list() expression.

Unlike _intlist() or _hexlist(), it's difficult to remove duplicates by the
caller of _list() because different symbols can point to the same revision.
If the caller knows all symbols are unique, that probably means revisions or
nodes are known, therefore, _intlist() or _hexlist() should be used instead.
So, it makes sense to check duplicates by _list() function.

'%ls' is no longer used in core, this won't cause performance regression.

diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -1920,9 +1920,18 @@ def _list(repo, subset, x):
     s = getstring(x, "internal error")
     if not s:
         return baseset()
-    ls = [repo[r].rev() for r in s.split('\0')]
-    s = subset
-    return baseset([r for r in ls if r in s])
+    # remove duplicates here. it's difficult for caller to deduplicate sets
+    # because different symbols can point to the same rev.
+    ls = []
+    seen = set()
+    for t in s.split('\0'):
+        r = repo[t].rev()
+        if r in seen:
+            continue
+        if r in subset:
+            ls.append(r)
+        seen.add(r)
+    return baseset(ls)
 
 # for internal use
 def _intlist(repo, subset, x):