[PATCH] perl/Git.pm: add rev_parse method

[Lea Wiemann <lewiemann@gmail.com>]

The rev_parse method translates a revision name to a SHA1 hash, like
the git-rev-parse command.

Signed-off-by: Lea Wiemann <LeWiemann@gmail.com>
---

This is part of my work to extend Git.pm to create a usable
repository access abstraction layer for gitweb.

I've tested this method by calling it with a few parameters, but
there's no test suite yet.  I'll probably send a message to the
mailing list about testing Git.pm soon.

This is my first patch to Git.pm, so please let me know if there is
anything wrong with it!

 perl/Git.pm |   22 ++++++++++++++++++++++
 1 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/perl/Git.pm b/perl/Git.pm
index d05b633..9ef8cb0 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -716,6 +716,28 @@ sub ident_person {
 	return "$ident[0] <$ident[1]>";
 }
 
+=item rev_parse ( REVISION_NAME )
+
+Look up the specified revision name and return the SHA1 hash, or
+return undef if the lookup failed.  See the git-rev-parse command.
+
+=cut
+
+sub rev_parse {
+    # We could allow for a list of revisions here.
+    my ($self, $rev_name) = @_;
+
+    my $hash;
+    try {
+        # The --default option works around rev-parse's lack of
+        # support for getopt style "--" separators (it would fail for
+        # tags named "--foo" without it).
+        $hash = $self->command_oneline("rev-parse", "--verify", "--default",
+                                       $rev_name);
+    } catch Git::Error::Command with { };
+    return undef unless defined $hash and $hash =~ /^([0-9a-fA-F]{40})$/;
+    $hash;
+}
 
 =item hash_object ( TYPE, FILENAME )
 
-- 
1.5.5.GIT