[PATCH] patch: add support for git delta hunks

[Nicolas Vigier]

On Wed, 27 Nov 2013, Augie Fackler wrote:

> On Tue, Nov 26, 2013 at 12:17:55PM +0100, Nicolas Vigier wrote:
> > # HG changeset patch
> > # User Nicolas Vigier <boklm at mars-attacks.org>
> > # Date 1385424419 -3600
> > # Node ID f8cb3b94a9f68dcca3d9545b14a7ecc21e8ba156
> > # Parent  1c46b18b0e1c47fa4cecf21b78c083a54ae9903f
> > patch: add support for git delta hunks
> >
> > When creating patches modifying binary files using "git format-patch",
> > git creates 'literal' and 'delta' hunks. Mercurial currently supports
> > 'literal' hunks only, which makes it impossible to import patches with
> > 'delta' hunks.
> >
> > This changeset adds support for 'delta' hunks. It is a reimplementation
> > of patch-delta.c from git :
> > http://git.kernel.org/cgit/git/git.git/tree/patch-delta.c
> >
> > diff -r 1c46b18b0e1c -r f8cb3b94a9f6 mercurial/patch.py
> > --- a/mercurial/patch.py	Fri Nov 22 17:26:58 2013 -0600
> > +++ b/mercurial/patch.py	Tue Nov 26 01:06:59 2013 +0100
> > @@ -721,8 +721,9 @@
> >              if self.remove:
> >                  self.backend.unlink(self.fname)
> >              else:
> > -                self.lines[:] = h.new()
> > -                self.offset += len(h.new())
> > +                l = h.new(self.lines)
> > +                self.lines[:] = l
> > +                self.offset += len(l)
> >                  self.dirty = True
> >              return 0
> >
> > @@ -1016,9 +1017,10 @@
> >          return old, oldstart, new, newstart
> >
> >  class binhunk(object):
> > -    'A binary patch file. Only understands literals so far.'
> > +    'A binary patch file.'
> >      def __init__(self, lr, fname):
> >          self.text = None
> > +        self.delta = False
> >          self.hunk = ['GIT binary patch\n']
> >          self._fname = fname
> >          self._read(lr)
> > @@ -1026,8 +1028,63 @@
> >      def complete(self):
> >          return self.text is not None
> >
> > -    def new(self):
> > -        return [self.text]
> > +    def new(self, lines):
> > +        def deltahead(binchunk):
> > +            i = 0
> > +            for c in binchunk:
> > +                i += 1
> > +                if not (ord(c) & 0x80):
> > +                    return i
> > +            return i
> > +        def applydelta(binchunk, data):
> 
> I may be missing something, but it look slike this nested function
> could be a module-level function and then be a little more readable?

Indeed, this could be a module-level function. I'll send a new patch.