--- a/mercurial/cmdutil.py	Wed Dec 06 15:29:17 2006 -0600
+++ b/mercurial/cmdutil.py	Wed Dec 06 17:58:09 2006 -0600
@@ -554,6 +554,25 @@
         return t
     return changeset_printer(ui, repo, patch, br, buffered)
 
+def finddate(ui, repo, date):
+    """Find the tipmost changeset that matches the given date spec"""
+    df = util.matchdate(date + " to " + date)
+    get = util.cachefunc(lambda r: repo.changectx(r).changeset())
+    changeiter, matchfn = walkchangerevs(ui, repo, [], get, {'rev':None})
+    results = {}
+    for st, rev, fns in changeiter:
+        if st == 'add':
+            d = get(rev)[2]
+            if df(d[0]):
+                results[rev] = d
+        elif st == 'iter':
+            if rev in results:
+                ui.status("Found revision %s from %s\n" %
+                          (rev, util.datestr(results[rev])))
+                return str(rev)
+
+    raise util.Abort(_("revision matching date not found"))
+
 def walkchangerevs(ui, repo, pats, change, opts):
     '''Iterate over files and the revs they changed in.
 

--- a/mercurial/commands.py	Wed Dec 06 15:29:17 2006 -0600
+++ b/mercurial/commands.py	Wed Dec 06 17:58:09 2006 -0600
@@ -222,6 +222,7 @@
         parent = p1
     hg.clean(repo, node, show_stats=False)
     revert_opts = opts.copy()
+    revert_opts['date'] = None
     revert_opts['all'] = True
     revert_opts['rev'] = hex(parent)
     revert(ui, repo, **revert_opts)
@@ -1596,7 +1597,7 @@
             ui.write("%3s " % (m.execf(f) and "755" or "644"))
         ui.write("%s\n" % f)
 
-def merge(ui, repo, node=None, force=None, branch=None):
+def merge(ui, repo, node=None, force=None, branch=None, date=None):
     """Merge working directory with another revision
 
     Merge the contents of the current working directory and the
@@ -1943,6 +1944,11 @@
     If no arguments are given, no files are reverted.
     """
 
+    if opts["date"]:
+        if opts["rev"]:
+            raise util.Abort(_("you can't specify a revision and a date"))
+        opts["rev"] = cmdutil.finddate(ui, repo, opts["date"])
+
     if not pats and not opts['all']:
         raise util.Abort(_('no files or directories specified; '
                            'use --all to revert the whole repo'))
@@ -2297,7 +2303,7 @@
     modheads = repo.addchangegroup(gen, 'unbundle', 'bundle:' + fname)
     return postincoming(ui, repo, modheads, opts['update'])
 
-def update(ui, repo, node=None, clean=False, branch=None):
+def update(ui, repo, node=None, clean=False, branch=None, date=None):
     """update or merge working directory
 
     Update the working directory to the specified revision.
@@ -2312,6 +2318,11 @@
     By default, update will refuse to run if doing so would require
     merging or discarding local changes.
     """
+    if date:
+        if node:
+            raise util.Abort(_("you can't specify a revision and a date"))
+        node = cmdutil.finddate(ui, repo, date)
+
     node = _lookup(repo, node, branch)
     if clean:
         return hg.clean(repo, node)
@@ -2676,6 +2687,7 @@
     "^revert":
         (revert,
          [('a', 'all', None, _('revert all changes when no arguments given')),
+          ('d', 'date', '', _('tipmost revision matching date')),
           ('r', 'rev', '', _('revision to revert to')),
           ('', 'no-backup', None, _('do not save backup copies of files')),
          ] + walkopts + dryrunopts,
@@ -2746,7 +2758,8 @@
         (update,
          [('b', 'branch', '',
            _('checkout the head of a specific branch (DEPRECATED)')),
-          ('C', 'clean', None, _('overwrite locally modified files'))],
+          ('C', 'clean', None, _('overwrite locally modified files')),
+          ('d', 'date', '', _('tipmost revision matching date'))],
          _('hg update [-C] [REV]')),
     "verify": (verify, [], _('hg verify')),
     "version": (version_, [], _('hg version')),