Handy describe_pg_lock function

I recently found the need to pretty-print the contents of pg_locks. So here's a little helper to do it, for anyone else who happens to have that need. pg_identify_object is far from adequate for the purpose. Reckon I should turn it into C and submit?

  CREATE FUNCTION describe_pg_lock(IN l pg_locks,
    OUT lock_objtype text, OUT lock_objschema text,
    OUT lock_objname text, OUT lock_objidentity text,
    OUT lock_objdescription text)
  LANGUAGE sql VOLATILE RETURNS NULL ON NULL INPUT AS
  $$
  SELECT
    *,
    CASE
      WHEN l.locktype IN ('relation', 'extend') THEN
        'relation ' || lo.lock_objidentity
      WHEN l.locktype = 'page' THEN
        'relation ' || lo.lock_objidentity || ' page ' || l.page
      WHEN l.locktype = 'tuple' THEN
        'relation ' || lo.lock_objidentity || ' page ' || l.page || ' tuple ' || l.tuple
      WHEN l.locktype = 'transactionid' THEN
        'transactionid ' || l.transactionid
      WHEN l.locktype = 'virtualxid' THEN
        'virtualxid ' || l.virtualxid
      WHEN l.locktype = 'speculative token' THEN
        'speculative token'
      WHEN lock_objidentity IS NOT NULL THEN
        l.locktype || ' ' || lo.lock_objidentity
      ELSE
        l.locktype
    END
  FROM (
    SELECT *
    FROM pg_identify_object('pg_class'::regclass, l.relation, 0)
    WHERE l.locktype IN ('relation', 'extend', 'page', 'tuple')
    UNION ALL
    SELECT *
    FROM pg_identify_object(l.classid, l.objid, l.objsubid)
    WHERE l.locktype NOT IN ('relation', 'extend', 'page', 'tuple')
  ) AS lo(lock_objtype, lock_objschema, lock_objname, lock_objidentity);
  $$;
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