--- a/hgext/mq.py
+++ b/hgext/mq.py
@@ -32,7 +32,7 @@ refresh contents of top applied patch   
 from mercurial.demandload import *
 from mercurial.i18n import gettext as _
 demandload(globals(), "os sys re struct traceback errno bz2")
-demandload(globals(), "mercurial:commands,hg,revlog,ui,util")
+demandload(globals(), "mercurial:commands,hg,patch,revlog,ui,util")
 
 commands.norepo += " qclone qversion"
 
@@ -65,6 +65,7 @@ class queue:
         self.guards_path = "guards"
         self.active_guards = None
         self.guards_dirty = False
+        self._diffopts = None
 
         if os.path.exists(self.join(self.series_path)):
             self.full_series = self.opener(self.series_path).read().splitlines()
@@ -74,6 +75,11 @@ class queue:
             lines = self.opener(self.status_path).read().splitlines()
             self.applied = [statusentry(l) for l in lines]
 
+    def diffopts(self):
+        if self._diffopts is None:
+            self._diffopts = self.ui.diffopts()
+        return self._diffopts
+
     def join(self, *p):
         return os.path.join(self.path, *p)
 
@@ -291,6 +297,11 @@ class queue:
             message.insert(0, subject)
         return (message, comments, user, date, diffstart > 1)
 
+    def printdiff(self, repo, node1, node2=None, files=None,
+                  fp=None, changes=None, opts=None):
+        patch.diff(repo, node1, node2, files,
+                   fp=fp, changes=changes, opts=self.diffopts())
+
     def mergeone(self, repo, mergeq, head, patch, rev, wlock):
         # first try just applying the patch
         (err, n) = self.apply(repo, [ patch ], update_status=False,
@@ -324,7 +335,7 @@ class queue:
         if comments:
             comments = "\n".join(comments) + '\n\n'
             patchf.write(comments)
-        commands.dodiff(patchf, self.ui, repo, head, n)
+        self.printdiff(repo, head, n, fp=patchf)
         patchf.close()
         return (0, n)
 
@@ -918,7 +929,7 @@ class queue:
             self.ui.write("No patches applied\n")
             return
         qp = self.qparents(repo, top)
-        commands.dodiff(sys.stdout, self.ui, repo, qp, None, files)
+        self.printdiff(repo, qp, files=files)
 
     def refresh(self, repo, msg='', short=False):
         if len(self.applied) == 0:
@@ -1001,8 +1012,8 @@ class queue:
             r = list(util.unique(dd))
             a = list(util.unique(aa))
             filelist = list(util.unique(c + r + a ))
-            commands.dodiff(patchf, self.ui, repo, patchparent, None,
-                            filelist, changes=(c, a, r, [], u))
+            self.printdiff(repo, patchparent, files=filelist,
+                           changes=(c, a, r, [], u), fp=patchf)
             patchf.close()
 
             changes = repo.changelog.read(tip)
@@ -1025,7 +1036,7 @@ class queue:
             self.applied[-1] = statusentry(revlog.hex(n), patch)
             self.applied_dirty = 1
         else:
-            commands.dodiff(patchf, self.ui, repo, patchparent, None)
+            self.printdiff(repo, patchparent, fp=patchf)
             patchf.close()
             self.pop(repo, force=True, wlock=wlock)
             self.push(repo, force=True, wlock=wlock)

--- a/hgext/notify.py
+++ b/hgext/notify.py
@@ -67,7 +67,7 @@
 from mercurial.demandload import *
 from mercurial.i18n import gettext as _
 from mercurial.node import *
-demandload(globals(), 'email.Parser mercurial:commands,templater,util')
+demandload(globals(), 'email.Parser mercurial:commands,patch,templater,util')
 demandload(globals(), 'fnmatch socket time')
 
 # template for single changeset can include email headers.
@@ -238,7 +238,7 @@ class notifier(object):
             return
         fp = templater.stringio()
         prev = self.repo.changelog.parents(node)[0]
-        commands.dodiff(fp, self.ui, self.repo, prev, ref)
+        patch.diff(self.repo, fp, prev, ref)
         difflines = fp.getvalue().splitlines(1)
         if maxdiff > 0 and len(difflines) > maxdiff:
             self.sio.write(_('\ndiffs (truncated from %d to %d lines):\n\n') %

new file mode 100644
--- /dev/null
+++ b/mercurial/cmdutil.py
@@ -0,0 +1,68 @@
+# commands.py - command processing for mercurial
+#
+# Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
+#
+# This software may be used and distributed according to the terms
+# of the GNU General Public License, incorporated herein by reference.
+
+from demandload import demandload
+from node import *
+from i18n import gettext as _
+demandload(globals(), 'os sys')
+
+def make_filename(repo, pat, node,
+                  total=None, seqno=None, revwidth=None, pathname=None):
+    node_expander = {
+        'H': lambda: hex(node),
+        'R': lambda: str(repo.changelog.rev(node)),
+        'h': lambda: short(node),
+        }
+    expander = {
+        '%': lambda: '%',
+        'b': lambda: os.path.basename(repo.root),
+        }
+
+    try:
+        if node:
+            expander.update(node_expander)
+        if node and revwidth is not None:
+            expander['r'] = (lambda:
+                    str(repo.changelog.rev(node)).zfill(revwidth))
+        if total is not None:
+            expander['N'] = lambda: str(total)
+        if seqno is not None:
+            expander['n'] = lambda: str(seqno)
+        if total is not None and seqno is not None:
+            expander['n'] = lambda:str(seqno).zfill(len(str(total)))
+        if pathname is not None:
+            expander['s'] = lambda: os.path.basename(pathname)
+            expander['d'] = lambda: os.path.dirname(pathname) or '.'
+            expander['p'] = lambda: pathname
+
+        newname = []
+        patlen = len(pat)
+        i = 0
+        while i < patlen:
+            c = pat[i]
+            if c == '%':
+                i += 1
+                c = pat[i]
+                c = expander[c]()
+            newname.append(c)
+            i += 1
+        return ''.join(newname)
+    except KeyError, inst:
+        raise util.Abort(_("invalid format spec '%%%s' in output file name"),
+                    inst.args[0])
+
+def make_file(repo, pat, node=None,
+              total=None, seqno=None, revwidth=None, mode='wb', pathname=None):
+    if not pat or pat == '-':
+        return 'w' in mode and sys.stdout or sys.stdin
+    if hasattr(pat, 'write') and 'w' in mode:
+        return pat
+    if hasattr(pat, 'read') and 'r' in mode:
+        return pat
+    return open(make_filename(repo, pat, node, total, seqno, revwidth,
+                              pathname),
+                mode)

--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -10,10 +10,10 @@ from node import *
 from i18n import gettext as _
 demandload(globals(), "os re sys signal shutil imp urllib pdb")
 demandload(globals(), "fancyopts ui hg util lock revlog templater bundlerepo")
-demandload(globals(), "fnmatch mdiff difflib patch random signal tempfile time")
+demandload(globals(), "fnmatch difflib patch random signal tempfile time")
 demandload(globals(), "traceback errno socket version struct atexit sets bz2")
 demandload(globals(), "archival cStringIO changegroup")
-demandload(globals(), "hgweb.server sshserver")
+demandload(globals(), "cmdutil hgweb.server sshserver")
 
 class UnknownCommand(Exception):
     """Exception raised if command is not in the command table."""
@@ -25,15 +25,6 @@ def bail_if_changed(repo):
     if modified or added or removed or deleted:
         raise util.Abort(_("outstanding uncommitted changes"))
 
-def filterfiles(filters, files):
-    l = [x for x in files if x in filters]
-
-    for t in filters:
-        if t and t[-1] != "/":
-            t += "/"
-        l += [x for x in files if x.startswith(t)]
-    return l
-
 def relpath(repo, args):
     cwd = repo.getcwd()
     if cwd:
@@ -344,63 +335,6 @@ def revrange(ui, repo, revs):
             seen[rev] = 1
             yield str(rev)
 
-def make_filename(repo, pat, node,
-                  total=None, seqno=None, revwidth=None, pathname=None):
-    node_expander = {
-        'H': lambda: hex(node),
-        'R': lambda: str(repo.changelog.rev(node)),
-        'h': lambda: short(node),
-        }
-    expander = {
-        '%': lambda: '%',
-        'b': lambda: os.path.basename(repo.root),
-        }
-
-    try:
-        if node:
-            expander.update(node_expander)
-        if node and revwidth is not None:
-            expander['r'] = (lambda:
-                    str(repo.changelog.rev(node)).zfill(revwidth))
-        if total is not None:
-            expander['N'] = lambda: str(total)
-        if seqno is not None:
-            expander['n'] = lambda: str(seqno)
-        if total is not None and seqno is not None:
-            expander['n'] = lambda:str(seqno).zfill(len(str(total)))
-        if pathname is not None:
-            expander['s'] = lambda: os.path.basename(pathname)
-            expander['d'] = lambda: os.path.dirname(pathname) or '.'
-            expander['p'] = lambda: pathname
-
-        newname = []
-        patlen = len(pat)
-        i = 0
-        while i < patlen:
-            c = pat[i]
-            if c == '%':
-                i += 1
-                c = pat[i]
-                c = expander[c]()
-            newname.append(c)
-            i += 1
-        return ''.join(newname)
-    except KeyError, inst:
-        raise util.Abort(_("invalid format spec '%%%s' in output file name"),
-                    inst.args[0])
-
-def make_file(repo, pat, node=None,
-              total=None, seqno=None, revwidth=None, mode='wb', pathname=None):
-    if not pat or pat == '-':
-        return 'w' in mode and sys.stdout or sys.stdin
-    if hasattr(pat, 'write') and 'w' in mode:
-        return pat
-    if hasattr(pat, 'read') and 'r' in mode:
-        return pat
-    return open(make_filename(repo, pat, node, total, seqno, revwidth,
-                              pathname),
-                mode)
-
 def write_bundle(cg, filename=None, compress=True):
     """Write a bundle file and return its filename.
 
@@ -453,74 +387,6 @@ def write_bundle(cg, filename=None, comp
         if cleanup is not None:
             os.unlink(cleanup)
 
-def dodiff(fp, ui, repo, node1, node2, files=None, match=util.always,
-           changes=None, text=False, opts={}):
-    if not node1:
-        node1 = repo.dirstate.parents()[0]
-    # reading the data for node1 early allows it to play nicely
-    # with repo.changes and the revlog cache.
-    change = repo.changelog.read(node1)
-    mmap = repo.manifest.read(change[0])
-    date1 = util.datestr(change[2])
-
-    if not changes:
-        changes = repo.changes(node1, node2, files, match=match)
-    modified, added, removed, deleted, unknown = changes
-    if files:
-        modified, added, removed = map(lambda x: filterfiles(files, x),
-                                       (modified, added, removed))
-
-    if not modified and not added and not removed:
-        return
-
-    if node2:
-        change = repo.changelog.read(node2)
-        mmap2 = repo.manifest.read(change[0])
-        _date2 = util.datestr(change[2])
-        def date2(f):
-            return _date2
-        def read(f):
-            return repo.file(f).read(mmap2[f])
-    else:
-        tz = util.makedate()[1]
-        _date2 = util.datestr()
-        def date2(f):
-            try:
-                return util.datestr((os.lstat(repo.wjoin(f)).st_mtime, tz))
-            except OSError, err:
-                if err.errno != errno.ENOENT: raise
-                return _date2
-        def read(f):
-            return repo.wread(f)
-
-    if ui.quiet:
-        r = None
-    else:
-        hexfunc = ui.verbose and hex or short
-        r = [hexfunc(node) for node in [node1, node2] if node]
-
-    diffopts = ui.diffopts()
-    showfunc = opts.get('show_function') or diffopts['showfunc']
-    ignorews = opts.get('ignore_all_space') or diffopts['ignorews']
-    ignorewsamount = opts.get('ignore_space_change') or \
-                     diffopts['ignorewsamount']
-    ignoreblanklines = opts.get('ignore_blank_lines') or \
-                     diffopts['ignoreblanklines']
-
-    all = modified + added + removed
-    all.sort()
-    for f in all:
-        to = None
-        tn = None
-        if f in mmap:
-            to = repo.file(f).read(mmap[f])
-        if f not in removed:
-            tn = read(f)
-        fp.write(mdiff.unidiff(to, date1, tn, date2(f), f, r, text=text,
-                               showfunc=showfunc, ignorews=ignorews,
-                               ignorewsamount=ignorewsamount,
-                               ignoreblanklines=ignoreblanklines))
-
 def trimuser(ui, name, rev, revcache):
     """trim the name of the user who committed a change"""
     user = revcache.get(rev)
@@ -922,7 +788,7 @@ def archive(ui, repo, dest, **opts):
             raise util.Abort(_('uncommitted merge - please provide a '
                                'specific revision'))
 
-    dest = make_filename(repo, dest, node)
+    dest = cmdutil.make_filename(repo, dest, node)
     if os.path.realpath(dest) == repo.root:
         raise util.Abort(_('repository root cannot be destination'))
     dummy, matchfn, dummy = matchpats(repo, [], opts)
@@ -933,7 +799,7 @@ def archive(ui, repo, dest, **opts):
             raise util.Abort(_('cannot archive plain files to stdout'))
         dest = sys.stdout
         if not prefix: prefix = os.path.basename(repo.root) + '-%h'
-    prefix = make_filename(repo, prefix, node)
+    prefix = cmdutil.make_filename(repo, prefix, node)
     archival.archive(repo, dest, node, kind, not opts['no_decode'],
                      matchfn, prefix)
 
@@ -1038,7 +904,7 @@ def cat(ui, repo, file1, *pats, **opts):
     """
     ctx = repo.changectx(opts['rev'] or "-1")
     for src, abs, rel, exact in walk(repo, (file1,) + pats, opts, ctx.node()):
-        fp = make_file(repo, opts['output'], ctx.node(), pathname=abs)
+        fp = cmdutil.make_file(repo, opts['output'], ctx.node(), pathname=abs)
         fp.write(ctx.filectx(abs).data())
 
 def clone(ui, source, dest=None, **opts):
@@ -1507,35 +1373,8 @@ def diff(ui, repo, *pats, **opts):
 
     fns, matchfn, anypats = matchpats(repo, pats, opts)
 
-    dodiff(sys.stdout, ui, repo, node1, node2, fns, match=matchfn,
-           text=opts['text'], opts=opts)
-
-def doexport(ui, repo, changeset, seqno, total, revwidth, opts):
-    node = repo.lookup(changeset)
-    parents = [p for p in repo.changelog.parents(node) if p != nullid]
-    if opts['switch_parent']:
-        parents.reverse()
-    prev = (parents and parents[0]) or nullid
-    change = repo.changelog.read(node)
-
-    fp = make_file(repo, opts['output'], node, total=total, seqno=seqno,
-                   revwidth=revwidth)
-    if fp != sys.stdout:
-        ui.note("%s\n" % fp.name)
-
-    fp.write("# HG changeset patch\n")
-    fp.write("# User %s\n" % change[1])
-    fp.write("# Date %d %d\n" % change[2])
-    fp.write("# Node ID %s\n" % hex(node))
-    fp.write("# Parent  %s\n" % hex(prev))
-    if len(parents) > 1:
-        fp.write("# Parent  %s\n" % hex(parents[1]))
-    fp.write(change[4].rstrip())
-    fp.write("\n\n")
-
-    dodiff(fp, ui, repo, prev, node, text=opts['text'])
-    if fp != sys.stdout:
-        fp.close()
+    patch.diff(repo, node1, node2, fns, match=matchfn,
+               opts=ui.diffopts(opts))
 
 def export(ui, repo, *changesets, **opts):
     """dump the header and diffs for one or more changesets
@@ -1566,15 +1405,13 @@ def export(ui, repo, *changesets, **opts
     """
     if not changesets:
         raise util.Abort(_("export requires at least one changeset"))
-    seqno = 0
     revs = list(revrange(ui, repo, changesets))
-    total = len(revs)
-    revwidth = max(map(len, revs))
-    msg = len(revs) > 1 and _("Exporting patches:\n") or _("Exporting patch:\n")
-    ui.note(msg)
-    for cset in revs:
-        seqno += 1
-        doexport(ui, repo, cset, seqno, total, revwidth, opts)
+    if len(revs) > 1:
+        ui.note(_('exporting patches:\n'))
+    else:
+        ui.note(_('exporting patch:\n'))
+    patch.export(repo, map(repo.lookup, revs), template=opts['output'],
+                 switch_parent=opts['switch_parent'], opts=ui.diffopts(opts))
 
 def forget(ui, repo, *pats, **opts):
     """don't add the specified files on the next commit (DEPRECATED)
@@ -1963,7 +1800,7 @@ def incoming(ui, repo, source="default",
             displayer.show(changenode=n)
             if opts['patch']:
                 prev = (parents and parents[0]) or nullid
-                dodiff(ui, ui, other, prev, n)
+                patch.diff(repo, other, prev, n)
                 ui.write("\n")
     finally:
         if hasattr(other, 'close'):
@@ -2114,7 +1951,7 @@ def log(ui, repo, *pats, **opts):
             displayer.show(rev, brinfo=br)
             if opts['patch']:
                 prev = (parents and parents[0]) or nullid
-                dodiff(du, du, repo, prev, changenode, match=matchfn)
+                patch.diff(repo, prev, changenode, match=matchfn, fp=du)
                 du.write("\n\n")
         elif st == 'iter':
             if count == limit: break
@@ -2195,7 +2032,7 @@ def outgoing(ui, repo, dest=None, **opts
         displayer.show(changenode=n)
         if opts['patch']:
             prev = (parents and parents[0]) or nullid
-            dodiff(ui, ui, repo, prev, n)
+            patch.diff(repo, prev, n)
             ui.write("\n")
 
 def parents(ui, repo, file_=None, rev=None, branches=None, **opts):
@@ -2843,7 +2680,7 @@ def tip(ui, repo, **opts):
         br = repo.branchlookup([n])
     show_changeset(ui, repo, opts).show(changenode=n, brinfo=br)
     if opts['patch']:
-        dodiff(ui, ui, repo, repo.changelog.parents(n)[0], n)
+        patch.diff(repo, repo.changelog.parents(n)[0], n)
 
 def unbundle(ui, repo, fname, **opts):
     """apply a changegroup file

--- a/mercurial/hgweb/hgweb_mod.py
+++ b/mercurial/hgweb/hgweb_mod.py
@@ -134,32 +134,22 @@ class hgweb(object):
             modified, added, removed = map(lambda x: filterfiles(files, x),
                                            (modified, added, removed))
 
-        diffopts = self.repo.ui.diffopts()
-        showfunc = diffopts['showfunc']
-        ignorews = diffopts['ignorews']
-        ignorewsamount = diffopts['ignorewsamount']
-        ignoreblanklines = diffopts['ignoreblanklines']
+        diffopts = ui.diffopts()
         for f in modified:
             to = r.file(f).read(mmap1[f])
             tn = r.file(f).read(mmap2[f])
             yield diffblock(mdiff.unidiff(to, date1, tn, date2, f,
-                            showfunc=showfunc, ignorews=ignorews,
-                            ignorewsamount=ignorewsamount,
-                            ignoreblanklines=ignoreblanklines), f, tn)
+                                          opts=diffopts), f, tn)
         for f in added:
             to = None
             tn = r.file(f).read(mmap2[f])
             yield diffblock(mdiff.unidiff(to, date1, tn, date2, f,
-                            showfunc=showfunc, ignorews=ignorews,
-                            ignorewsamount=ignorewsamount,
-                            ignoreblanklines=ignoreblanklines), f, tn)
+                                          opts=diffopts), f, tn)
         for f in removed:
             to = r.file(f).read(mmap1[f])
             tn = None
             yield diffblock(mdiff.unidiff(to, date1, tn, date2, f,
-                            showfunc=showfunc, ignorews=ignorews,
-                            ignorewsamount=ignorewsamount,
-                            ignoreblanklines=ignoreblanklines), f, tn)
+                                          opts=diffopts), f, tn)
 
     def changelog(self, pos, shortlog=False):
         def changenav(**map):

--- a/mercurial/mdiff.py
+++ b/mercurial/mdiff.py
@@ -19,14 +19,39 @@ def splitnewlines(text):
             lines[-1] = lines[-1][:-1]
     return lines
 
-def unidiff(a, ad, b, bd, fn, r=None, text=False,
-            showfunc=False, ignorews=False, ignorewsamount=False,
-            ignoreblanklines=False):
+class diffopts(object):
+    '''context is the number of context lines
+    text treats all files as text
+    showfunc enables diff -p output
+    ignorews ignores all whitespace changes in the diff
+    ignorewsamount ignores changes in the amount of whitespace
+    ignoreblanklines ignores changes whose lines are all blank'''
 
+    defaults = {
+        'context': 3,
+        'text': False,
+        'showfunc': True,
+        'ignorews': False,
+        'ignorewsamount': False,
+        'ignoreblanklines': False,
+        }
+
+    __slots__ = defaults.keys()
+
+    def __init__(self, **opts):
+        for k in self.__slots__:
+            v = opts.get(k)
+            if v is None:
+                v = self.defaults[k]
+            setattr(self, k, v)
+
+defaultopts = diffopts()
+
+def unidiff(a, ad, b, bd, fn, r=None, opts=defaultopts):
     if not a and not b: return ""
     epoch = util.datestr((0, 0))
 
-    if not text and (util.binary(a) or util.binary(b)):
+    if not opts.text and (util.binary(a) or util.binary(b)):
         l = ['Binary file %s has changed\n' % fn]
     elif not a:
         b = splitnewlines(b)
@@ -49,10 +74,7 @@ def unidiff(a, ad, b, bd, fn, r=None, te
     else:
         al = splitnewlines(a)
         bl = splitnewlines(b)
-        l = list(bunidiff(a, b, al, bl, "a/" + fn, "b/" + fn,
-                          showfunc=showfunc, ignorews=ignorews,
-                          ignorewsamount=ignorewsamount,
-                          ignoreblanklines=ignoreblanklines))
+        l = list(bunidiff(a, b, al, bl, "a/" + fn, "b/" + fn, opts=opts))
         if not l: return ""
         # difflib uses a space, rather than a tab
         l[0] = "%s\t%s\n" % (l[0][:-2], ad)
@@ -72,21 +94,15 @@ def unidiff(a, ad, b, bd, fn, r=None, te
 # t1 and t2 are the text to be diffed
 # l1 and l2 are the text broken up into lines
 # header1 and header2 are the filenames for the diff output
-# context is the number of context lines
-# showfunc enables diff -p output
-# ignorews ignores all whitespace changes in the diff
-# ignorewsamount ignores changes in the amount of whitespace
-# ignoreblanklines ignores changes whose lines are all blank
-def bunidiff(t1, t2, l1, l2, header1, header2, context=3, showfunc=False,
-             ignorews=False, ignorewsamount=False, ignoreblanklines=False):
+def bunidiff(t1, t2, l1, l2, header1, header2, opts=defaultopts):
     def contextend(l, len):
-        ret = l + context
+        ret = l + opts.context
         if ret > len:
             ret = len
         return ret
 
     def contextstart(l):
-        ret = l - context
+        ret = l - opts.context
         if ret < 0:
             return 0
         return ret
@@ -101,7 +117,7 @@ def bunidiff(t1, t2, l1, l2, header1, he
         blen = b2 - bstart + aend - a2
 
         func = ""
-        if showfunc:
+        if opts.showfunc:
             # walk backwards from the start of the context
             # to find a line starting with an alphanumeric char.
             for x in xrange(astart, -1, -1):
@@ -119,14 +135,14 @@ def bunidiff(t1, t2, l1, l2, header1, he
 
     header = [ "--- %s\t\n" % header1, "+++ %s\t\n" % header2 ]
 
-    if showfunc:
+    if opts.showfunc:
         funcre = re.compile('\w')
-    if ignorewsamount:
+    if opts.ignorewsamount:
         wsamountre = re.compile('[ \t]+')
         wsappendedre = re.compile(' \n')
-    if ignoreblanklines:
+    if opts.ignoreblanklines:
         wsblanklinesre = re.compile('\n')
-    if ignorews:
+    if opts.ignorews:
         wsre = re.compile('[ \t]')
 
     # bdiff.blocks gives us the matching sequences in the files.  The loop
@@ -159,13 +175,13 @@ def bunidiff(t1, t2, l1, l2, header1, he
         if not old and not new:
             continue
 
-        if ignoreblanklines:
+        if opts.ignoreblanklines:
             wsold = wsblanklinesre.sub('', "".join(old))
             wsnew = wsblanklinesre.sub('', "".join(new))
             if wsold == wsnew:
                 continue
 
-        if ignorewsamount:
+        if opts.ignorewsamount:
             wsold = wsamountre.sub(' ', "".join(old))
             wsold = wsappendedre.sub('\n', wsold)
             wsnew = wsamountre.sub(' ', "".join(new))
@@ -173,7 +189,7 @@ def bunidiff(t1, t2, l1, l2, header1, he
             if wsold == wsnew:
                 continue
 
-        if ignorews:
+        if opts.ignorews:
             wsold = wsre.sub('', "".join(old))
             wsnew = wsre.sub('', "".join(new))
             if wsold == wsnew:
@@ -184,7 +200,7 @@ def bunidiff(t1, t2, l1, l2, header1, he
         prev = None
         if hunk:
             # join with the previous hunk if it falls inside the context
-            if astart < hunk[1] + context + 1:
+            if astart < hunk[1] + opts.context + 1:
                 prev = hunk
                 astart = hunk[1]
                 bstart = hunk[3]

--- a/mercurial/patch.py
+++ b/mercurial/patch.py
@@ -7,8 +7,9 @@
 
 from demandload import demandload
 from i18n import gettext as _
-demandload(globals(), "util")
-demandload(globals(), "cStringIO email.Parser os re shutil tempfile")
+from node import *
+demandload(globals(), "cmdutil mdiff util")
+demandload(globals(), "cStringIO email.Parser os re shutil sys tempfile")
 
 def extract(ui, fileobj):
     '''extract patch from data read from fileobj.
@@ -249,3 +250,117 @@ def patch(strip, patchname, ui, cwd=None
         files[gp.path] = (gp.op, gp)
 
     return files
+
+def diff(repo, node1=None, node2=None, files=None, match=util.always,
+         fp=None, changes=None, opts=None):
+    '''print diff of changes to files between two nodes, or node and
+    working directory.
+
+    if node1 is None, use first dirstate parent instead.
+    if node2 is None, compare node1 with working directory.'''
+
+    if opts is None:
+        opts = mdiff.defaultopts
+    if fp is None:
+        fp = repo.ui
+
+    if not node1:
+        node1 = repo.dirstate.parents()[0]
+    # reading the data for node1 early allows it to play nicely
+    # with repo.changes and the revlog cache.
+    change = repo.changelog.read(node1)
+    mmap = repo.manifest.read(change[0])
+    date1 = util.datestr(change[2])
+
+    if not changes:
+        changes = repo.changes(node1, node2, files, match=match)
+    modified, added, removed, deleted, unknown = changes
+    if files:
+        def filterfiles(filters):
+            l = [x for x in files if x in filters]
+
+            for t in filters:
+                if t and t[-1] != "/":
+                    t += "/"
+                l += [x for x in files if x.startswith(t)]
+            return l
+
+        modified, added, removed = map(lambda x: filterfiles(x),
+                                       (modified, added, removed))
+
+    if not modified and not added and not removed:
+        return
+
+    if node2:
+        change = repo.changelog.read(node2)
+        mmap2 = repo.manifest.read(change[0])
+        _date2 = util.datestr(change[2])
+        def date2(f):
+            return _date2
+        def read(f):
+            return repo.file(f).read(mmap2[f])
+    else:
+        tz = util.makedate()[1]
+        _date2 = util.datestr()
+        def date2(f):
+            try:
+                return util.datestr((os.lstat(repo.wjoin(f)).st_mtime, tz))
+            except OSError, err:
+                if err.errno != errno.ENOENT: raise
+                return _date2
+        def read(f):
+            return repo.wread(f)
+
+    if repo.ui.quiet:
+        r = None
+    else:
+        hexfunc = repo.ui.verbose and hex or short
+        r = [hexfunc(node) for node in [node1, node2] if node]
+
+    all = modified + added + removed
+    all.sort()
+    for f in all:
+        to = None
+        tn = None
+        if f in mmap:
+            to = repo.file(f).read(mmap[f])
+        if f not in removed:
+            tn = read(f)
+        fp.write(mdiff.unidiff(to, date1, tn, date2(f), f, r, opts=opts))
+
+def export(repo, revs, template='hg-%h.patch', fp=None, switch_parent=False,
+           opts=None):
+    '''export changesets as hg patches.'''
+
+    total = len(revs)
+    revwidth = max(map(len, revs))
+
+    def single(node, seqno, fp):
+        parents = [p for p in repo.changelog.parents(node) if p != nullid]
+        if switch_parent:
+            parents.reverse()
+        prev = (parents and parents[0]) or nullid
+        change = repo.changelog.read(node)
+
+        if not fp:
+            fp = cmdutil.make_file(repo, template, node, total=total,
+                                   seqno=seqno, revwidth=revwidth)
+        if fp not in (sys.stdout, repo.ui):
+            repo.ui.note("%s\n" % fp.name)
+
+        fp.write("# HG changeset patch\n")
+        fp.write("# User %s\n" % change[1])
+        fp.write("# Date %d %d\n" % change[2])
+        fp.write("# Node ID %s\n" % hex(node))
+        fp.write("# Parent  %s\n" % hex(prev))
+        if len(parents) > 1:
+            fp.write("# Parent  %s\n" % hex(parents[1]))
+        fp.write(change[4].rstrip())
+        fp.write("\n\n")
+
+        diff(repo, prev, node, fp=fp, opts=opts)
+        if fp not in (sys.stdout, repo.ui):
+            fp.close()
+
+    for seqno, cset in enumerate(revs):
+        single(cset, seqno, fp)

--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -8,7 +8,7 @@
 from i18n import gettext as _
 from demandload import *
 demandload(globals(), "errno getpass os re smtplib socket sys tempfile")
-demandload(globals(), "ConfigParser templater traceback util")
+demandload(globals(), "ConfigParser mdiff templater traceback util")
 
 class ui(object):
     def __init__(self, verbose=False, debug=False, quiet=False,
@@ -169,16 +169,17 @@ class ui(object):
             result[key.lower()] = value
         return result
 
-    def diffopts(self):
-        if self.diffcache:
-            return self.diffcache
-        result = {'showfunc': True, 'ignorews': False,
-                  'ignorewsamount': False, 'ignoreblanklines': False}
-        for key, value in self.configitems("diff"):
-            if value:
-                result[key.lower()] = (value.lower() == 'true')
-        self.diffcache = result
-        return result
+    def diffopts(self, opts={}):
+        return mdiff.diffopts(
+            text=opts.get('text'),
+            showfunc=(opts.get('show_function') or
+                      self.configbool('diff', 'showfunc', None)),
+            ignorews=(opts.get('ignore_all_space') or
+                      self.configbool('diff', 'ignorews', None)),
+            ignorewsamount=(opts.get('ignore_space_change') or
+                            self.configbool('diff', 'ignorewsamount', None)),
+            ignoreblanklines=(opts.get('ignore_blank_lines') or
+                              self.configbool('diff', 'ignoreblanklines', None)))
 
     def username(self):
         """Return default username to be used in commits.