Mercurial > hg
diff mercurial/pure/bdiff.py @ 7703:9044d3567f6d
pure Python implementation of bdiff.c
author | Martin Geisler <mg@daimi.au.dk> |
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date | Sat, 24 Jan 2009 00:12:20 +0100 |
parents | |
children | e9b48afd0e78 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mercurial/pure/bdiff.py Sat Jan 24 00:12:20 2009 +0100 @@ -0,0 +1,69 @@ +# bdiff.py - Python implementation of bdiff.c +# +# Copyright 2009 Matt Mackall <mpm@selenic.com> and others +# +# This software may be used and distributed according to the terms +# of the GNU General Public License, incorporated herein by reference. + +import struct, difflib +# mdiff import moved to bottom due to import cycle + +def _normalizeblocks(a, b, blocks): + prev = None + for curr in blocks: + if prev is None: + prev = curr + continue + shift = 0 + + a1, b1, l1 = prev + a1end = a1 + l1 + b1end = b1 + l1 + + a2, b2, l2 = curr + a2end = a2 + l2 + b2end = b2 + l2 + if a1end == a2: + while a1end+shift < a2end and a[a1end+shift] == b[b1end+shift]: + shift += 1 + elif b1end == b2: + while b1end+shift < b2end and a[a1end+shift] == b[b1end+shift]: + shift += 1 + yield a1, b1, l1+shift + prev = a2+shift, b2+shift, l2-shift + yield prev + +def bdiff(a, b): + a = str(a).splitlines(True) + b = str(b).splitlines(True) + + if not a: + s = "".join(b) + return s and (struct.pack(">lll", 0, 0, len(s)) + s) + + bin = [] + p = [0] + for i in a: p.append(p[-1] + len(i)) + + d = difflib.SequenceMatcher(None, a, b).get_matching_blocks() + d = _normalizeblocks(a, b, d) + la = 0 + lb = 0 + for am, bm, size in d: + s = "".join(b[lb:bm]) + if am > la or s: + bin.append(struct.pack(">lll", p[la], p[am], len(s)) + s) + la = am + size + lb = bm + size + + return "".join(bin) + +def blocks(a, b): + an = mdiff.splitnewlines(a) + bn = mdiff.splitnewlines(b) + d = difflib.SequenceMatcher(None, an, bn).get_matching_blocks() + d = _normalizeblocks(an, bn, d) + return [(i, i + n, j, j + n) for (i, j, n) in d] + +# this breaks an import cycle +import mdiff