# HG changeset patch
# User Kevin Bullock <kbullock@ringworld.org>
# Date 2010-11-04 21:59:03
# Node ID a5f7f1e9340e2cb19882fc64d7370a61124fe63f
# Parent  b6245c2470a924cf73dc74fe5a6499b7a48c8caa

revsets: let p1() and p2() return parents of working dir

This patch makes the 'set' argument to revset functions p1() and p2()
optional. If no argument is given, p1() and p2() return the first or second
parent of the working directory.

If the working directory is not an in-progress merge (no 2nd parent), p2()
returns the empty set. For a checkout of the null changeset, both p1() and
p2() return the empty set.

diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -202,9 +202,12 @@ def rev(repo, subset, x):
     return [r for r in subset if r == l]
 
 def p1(repo, subset, x):
-    """``p1(set)``
-    First parent of changesets in set.
+    """``p1([set])``
+    First parent of changesets in set, or the working directory.
     """
+    if x is None:
+        return [repo[x].parents()[0].rev()]
+
     ps = set()
     cl = repo.changelog
     for r in getset(repo, range(len(repo)), x):
@@ -212,9 +215,16 @@ def p1(repo, subset, x):
     return [r for r in subset if r in ps]
 
 def p2(repo, subset, x):
-    """``p2(set)``
-    Second parent of changesets in set.
+    """``p2([set])``
+    Second parent of changesets in set, or the working directory.
     """
+    if x is None:
+        ps = repo[x].parents()
+        try:
+            return [ps[1].rev()]
+        except IndexError:
+            return []
+
     ps = set()
     cl = repo.changelog
     for r in getset(repo, range(len(repo)), x):
diff --git a/tests/test-revset-dirstate-parents.t b/tests/test-revset-dirstate-parents.t
new file mode 100644
--- /dev/null
+++ b/tests/test-revset-dirstate-parents.t
@@ -0,0 +1,42 @@
+  $ HGENCODING=utf-8
+  $ export HGENCODING
+
+  $ try() {
+  >   hg debugrevspec --debug $@
+  > }
+
+  $ log() {
+  >   hg log --template '{rev}\n' -r "$1"
+  > }
+
+  $ hg init repo
+  $ cd repo
+
+  $ try 'p1()'
+  ('func', ('symbol', 'p1'), None)
+  -1
+  $ try 'p2()'
+  ('func', ('symbol', 'p2'), None)
+
+null revision
+  $ log 'p1()'
+  $ log 'p2()'
+
+working dir with a single parent
+  $ echo a > a
+  $ hg ci -Aqm0
+  $ log 'p1()'
+  0
+  $ log 'p2()'
+
+merge in progress
+  $ echo b > b
+  $ hg ci -Aqm1
+  $ hg up -q 0
+  $ echo c > c
+  $ hg ci -Aqm2
+  $ hg merge -q
+  $ log 'p1()'
+  2
+  $ log 'p2()'
+  1