Mercurial > hg
view mercurial/cffi/bdiff.py @ 45059:79f6f9fa18c1
documentation: add some internals documentation about bid merge
This is an important algorithm that was only documented on the wiki so far.
Some update to the algorithm (and associated doc) is to expected in the future
since the bid merge algorithm is bug-ridden when it comes to file deletion comes
to play.
Differential Revision: https://phab.mercurial-scm.org/D8711
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
---|---|
date | Mon, 22 Jun 2020 13:32:20 +0200 |
parents | 687b865b95ad |
children | 521ac0d7047f |
line wrap: on
line source
# bdiff.py - CFFI implementation of bdiff.c # # Copyright 2016 Maciej Fijalkowski <fijall@gmail.com> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from __future__ import absolute_import import struct from ..pure.bdiff import * from . import _bdiff ffi = _bdiff.ffi lib = _bdiff.lib def blocks(sa, sb): a = ffi.new(b"struct bdiff_line**") b = ffi.new(b"struct bdiff_line**") ac = ffi.new(b"char[]", str(sa)) bc = ffi.new(b"char[]", str(sb)) l = ffi.new(b"struct bdiff_hunk*") try: an = lib.bdiff_splitlines(ac, len(sa), a) bn = lib.bdiff_splitlines(bc, len(sb), b) if not a[0] or not b[0]: raise MemoryError count = lib.bdiff_diff(a[0], an, b[0], bn, l) if count < 0: raise MemoryError rl = [None] * count h = l.next i = 0 while h: rl[i] = (h.a1, h.a2, h.b1, h.b2) h = h.next i += 1 finally: lib.free(a[0]) lib.free(b[0]) lib.bdiff_freehunks(l.next) return rl def bdiff(sa, sb): a = ffi.new(b"struct bdiff_line**") b = ffi.new(b"struct bdiff_line**") ac = ffi.new(b"char[]", str(sa)) bc = ffi.new(b"char[]", str(sb)) l = ffi.new(b"struct bdiff_hunk*") try: an = lib.bdiff_splitlines(ac, len(sa), a) bn = lib.bdiff_splitlines(bc, len(sb), b) if not a[0] or not b[0]: raise MemoryError count = lib.bdiff_diff(a[0], an, b[0], bn, l) if count < 0: raise MemoryError rl = [] h = l.next la = lb = 0 while h: if h.a1 != la or h.b1 != lb: lgt = (b[0] + h.b1).l - (b[0] + lb).l rl.append( struct.pack( b">lll", (a[0] + la).l - a[0].l, (a[0] + h.a1).l - a[0].l, lgt, ) ) rl.append(str(ffi.buffer((b[0] + lb).l, lgt))) la = h.a2 lb = h.b2 h = h.next finally: lib.free(a[0]) lib.free(b[0]) lib.bdiff_freehunks(l.next) return b"".join(rl)