class _DiffEngine (View source)
Class used internally by Diff to actually compute the diffs.
The algorithm used here is mostly lifted from the perl module Algorithm::Diff (version 1.06) by Ned Konz, which is available at: http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
More ideas are taken from: http://www.ics.uci.edu/~eppstein/161/960229.html
Some ideas are (and a bit of code) are from from analyze.c, from GNU diffutils-2.7, which can be found at: ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
Finally, some ideas (subdivision by NCHUNKS > 2, and some optimizations) are my own.
_diag($xoff, $xlim, $yoff, $ylim, $nchunks)
_compareseq($xoff, $xlim, $yoff, $ylim)
_shift_boundaries($lines, $changed, $other_changed)