mercurial/pure/bdiff.py
author Martin Geisler <mg@lazybytes.net>
Sun, 27 Sep 2009 10:12:02 +0200
changeset 9485 7d6ac5d7917c
parent 8225 46293a0c7e9f
child 10263 25e572394f5c
permissions -rw-r--r--
test-gendoc: add tests for all languages This ensures that we catch errors in the reST syntax early and for all languages. The only change needed in gendoc.py was to correct the computation of section underlines for Asian languages.

# 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 version 2, incorporated herein by reference.

import struct, difflib

def splitnewlines(text):
    '''like str.splitlines, but only split on newlines.'''
    lines = [l + '\n' for l in text.split('\n')]
    if lines:
        if lines[-1] == '\n':
            lines.pop()
        else:
            lines[-1] = lines[-1][:-1]
    return lines

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 = splitnewlines(a)
    bn = 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]