Hi,
On Wed, 7 Jan 2009, Davide Libenzi wrote:
> On Wed, 7 Jan 2009, Johannes Schindelin wrote:
>
> > The patience diff algorithm produces slightly more intuitive output
> > than the classic Myers algorithm, as it does not try to minimize the
> > number of +/- lines first, but tries to preserve the lines that are
> > unique.
>
> Johannes, sorry I had not time to follow this one.
What? You mean you actually took some time off around Christmas???
:-)
> A couple of minor comments that arose just at glancing at the patch.
Thanks.
> > +/*
> > + * LibXDiff by Davide Libenzi ( File Differential Library )
> > + * Copyright (C) 2003-2009 Davide Libenzi, Johannes E. Schindelin
> > + *
> > + * This library is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU Lesser General Public
> > + * License as published by the Free Software Foundation; either
> > + * version 2.1 of the License, or (at your option) any later version.
> > + *
> > + * This library is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > + * Lesser General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU Lesser General Public
> > + * License along with this library; if not, write to the Free Software
> > + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
> > + *
> > + * Davide Libenzi <davidel@xxxxxxxxxxxxxxx>
>
> You do not need to give me credit for something I don't even know how it
> works ;)
Well, I meant to pass the copyright to you, or at least share it.
> > +static int fall_back_to_classic_diff(struct hashmap *map,
> > + int line1, int count1, int line2, int count2)
> > +{
> > + /*
> > + * This probably does not work outside Git, since
> > + * we have a very simple mmfile structure.
> > + *
> > + * Note: ideally, we would reuse the prepared environment, but
> > + * the libxdiff interface does not (yet) allow for diffing only
> > + * ranges of lines instead of the whole files.
> > + */
> > + mmfile_t subfile1, subfile2;
> > + xpparam_t xpp;
> > + xdfenv_t env;
> > +
> > + subfile1.ptr = (char *)map->env->xdf1.recs[line1 - 1]->ptr;
> > + subfile1.size = map->env->xdf1.recs[line1 + count1 - 2]->ptr +
> > + map->env->xdf1.recs[line1 + count1 - 2]->size - subfile1.ptr;
> > + subfile2.ptr = (char *)map->env->xdf2.recs[line2 - 1]->ptr;
> > + subfile2.size = map->env->xdf2.recs[line2 + count2 - 2]->ptr +
> > + map->env->xdf2.recs[line2 + count2 - 2]->size - subfile2.ptr;
> > + xpp.flags = map->xpp->flags & ~XDF_PATIENCE_DIFF;
> > + if (xdl_do_diff(&subfile1, &subfile2, &xpp, &env) < 0)
> > + return -1;
>
> xdiff allows for diffing ranges, and the most efficent method is exactly
> how you did ;) Once you know the lines pointers, there's no need to pass
> it the whole file and have it scan it whole to find the lines range it
> has to diff. Just pass the limited view like you did.
Heh.
Could it be that you misread my patch, and assumed that I faked an
xdfenv?
I did not, but instead faked two mmfiles, which is only as simple as I did
it because in git.git, we only have contiguous mmfiles. (I recall that
libxdiff allows for ropes instead of arrays.)
The way I did it has one big shortcoming: I need to prepare an xdfenv for
the subfiles even if I already prepared one for the complete files. IOW
the lines are rehashed all over again.
Ciao,
Dscho
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