mercurial/mdiff.py

Implement data inlined with the index file

This patch allows you to optionally inline data bytes with the
revlog index file.  It saves considerable space and checkout
time by reducing the number of inodes, wasted partial blocks and
system calls.

To use the inline data add this to your .hgrc

[revlog]
# inline data only works with revlogng
format=1
# inline is the only valid flag right now.
flags=inline

# mdiff.py - diff and patch routines for mercurial
#
# Copyright 2005 Matt Mackall <[e-mail]>
#
# 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
import struct, bdiff, util, mpatch
demandload(globals(), "re")


def unidiff(a, ad, b, bd, fn, r=None, text=False,
            showfunc=False, ignorews=False):

    if not a and not b: return ""
    epoch = util.datestr((0, 0))

    if not text and (util.binary(a) or util.binary(b)):
        l = ['Binary file %s has changed\n' % fn]
    elif not a:
        b = b.splitlines(1)
        if a is None:
            l1 = "--- %s\t%s\n" % ("/dev/null", epoch)
        else:
            l1 = "--- %s\t%s\n" % ("a/" + fn, ad)
        l2 = "+++ %s\t%s\n" % ("b/" + fn, bd)
        l3 = "@@ -0,0 +1,%d @@\n" % len(b)
        l = [l1, l2, l3] + ["+" + e for e in b]
    elif not b:
        a = a.splitlines(1)
        l1 = "--- %s\t%s\n" % ("a/" + fn, ad)
        if b is None:
            l2 = "+++ %s\t%s\n" % ("/dev/null", epoch)
        else:
            l2 = "+++ %s\t%s\n" % ("b/" + fn, bd)
        l3 = "@@ -1,%d +0,0 @@\n" % len(a)
        l = [l1, l2, l3] + ["-" + e for e in a]
    else:
        al = a.splitlines(1)
        bl = b.splitlines(1)
        l = list(bunidiff(a, b, al, bl, "a/" + fn, "b/" + fn,
                          showfunc=showfunc, ignorews=ignorews))
        if not l: return ""
        # difflib uses a space, rather than a tab
        l[0] = "%s\t%s\n" % (l[0][:-2], ad)
        l[1] = "%s\t%s\n" % (l[1][:-2], bd)

    for ln in xrange(len(l)):
        if l[ln][-1] != '\n':
            l[ln] += "\n\ No newline at end of file\n"

    if r:
        l.insert(0, "diff %s %s\n" %
                    (' '.join(["-r %s" % rev for rev in r]), fn))

    return "".join(l)

# somewhat self contained replacement for difflib.unified_diff
# 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
def bunidiff(t1, t2, l1, l2, header1, header2, context=3, showfunc=False,
             ignorews=False):
    def contextend(l, len):
        ret = l + context
        if ret > len:
            ret = len
        return ret

    def contextstart(l):
        ret = l - context
        if ret < 0:
            return 0
        return ret

    def yieldhunk(hunk, header):
        if header:
            for x in header:
                yield x
        (astart, a2, bstart, b2, delta) = hunk
        aend = contextend(a2, len(l1))
        alen = aend - astart
        blen = b2 - bstart + aend - a2

        func = ""
        if 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):
                t = l1[x].rstrip()
                if funcre.match(t):
                    func = ' ' + t[:40]
                    break

        yield "@@ -%d,%d +%d,%d @@%s\n" % (astart + 1, alen,
                                           bstart + 1, blen, func)
        for x in delta:
            yield x
        for x in xrange(a2, aend):
            yield ' ' + l1[x]

    header = [ "--- %s\t\n" % header1, "+++ %s\t\n" % header2 ]

    if showfunc:
        funcre = re.compile('\w')
    if ignorews:
        wsre = re.compile('[ \t]')

    # bdiff.blocks gives us the matching sequences in the files.  The loop
    # below finds the spaces between those matching sequences and translates
    # them into diff output.
    #
    diff = bdiff.blocks(t1, t2)
    hunk = None
    for i in xrange(len(diff)):
        # The first match is special.
        # we've either found a match starting at line 0 or a match later
        # in the file.  If it starts later, old and new below will both be
        # empty and we'll continue to the next match.
        if i > 0:
            s = diff[i-1]
        else:
            s = [0, 0, 0, 0]
        delta = []
        s1 = diff[i]
        a1 = s[1]
        a2 = s1[0]
        b1 = s[3]
        b2 = s1[2]

        old = l1[a1:a2]
        new = l2[b1:b2]

        # bdiff sometimes gives huge matches past eof, this check eats them,
        # and deals with the special first match case described above
        if not old and not new:
            continue

        if ignorews:
            wsold = wsre.sub('', "".join(old))
            wsnew = wsre.sub('', "".join(new))
            if wsold == wsnew:
                continue

        astart = contextstart(a1)
        bstart = contextstart(b1)
        prev = None
        if hunk:
            # join with the previous hunk if it falls inside the context
            if astart < hunk[1] + context + 1:
                prev = hunk
                astart = hunk[1]
                bstart = hunk[3]
            else:
                for x in yieldhunk(hunk, header):
                    yield x
                # we only want to yield the header if the files differ, and
                # we only want to yield it once.
                header = None
        if prev:
            # we've joined the previous hunk, record the new ending points.
            hunk[1] = a2
            hunk[3] = b2
            delta = hunk[4]
        else:
            # create a new hunk
            hunk = [ astart, a2, bstart, b2, delta ]

        delta[len(delta):] = [ ' ' + x for x in l1[astart:a1] ]
        delta[len(delta):] = [ '-' + x for x in old ]
        delta[len(delta):] = [ '+' + x for x in new ]

    if hunk:
        for x in yieldhunk(hunk, header):
            yield x

def patchtext(bin):
    pos = 0
    t = []
    while pos < len(bin):
        p1, p2, l = struct.unpack(">lll", bin[pos:pos + 12])
        pos += 12
        t.append(bin[pos:pos + l])
        pos += l
    return "".join(t)

def patch(a, bin):
    return mpatch.patches(a, [bin])

patches = mpatch.patches
textdiff = bdiff.bdiff