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=head1 NAME

Algorithm::LCS::XS - Fast (XS) implementation of the
                 Longest Common Subsequence (LCS) Algorithm

=head1 SYNOPSIS

  use Algorithm::LCS::XS qw/ADLCS LCSidx/;

  $alg = Algorithm::LCS::XS->new;
  @lcs = $alg->LCS(\@a,\@b);

  $cb = $alg->callback(@b); # closure
  @lcs = $cb->(\@a);        # same result as prior LCS() call

=head1 ABSTRACT

Algorithm::LCS::XS reimplements Algorithm::Diff's core loop in XS,
and provides a simple OO interface to it.

Extract from the Algorithm::Diff v1.15 manpage:

  The algorithm is that described in
  I<A Fast Algorithm for Computing Longest Common Subsequences>,
  CACM, vol.20, no.5, pp.350-353, May 1977, with a few
  minor improvements to improve the speed.


=head1 DESCRIPTION

=head2 CONSTRUCTOR

=over 4

=item new()

Creates a new object which maintains internal storage areas
for the LCS computation.  Use one of these per concurrent
LCS() call.

=back

=head2 METHODS

=over 4

=item line_map(@lines)

Send @lines to a hashref containing elements of the form

       @lines entry => [(increasing) list of matching indices]

=item callback(@lines)

Generates a closure capturing the object and line_map hash for @lines.
Most useful when computing multiple LCSs against a single file.

=item LCS(\@a,\@b)

Finds a Longest Common Subsequence, taking two arrayrefs as method
arguments.  In scalar context the return value is the length of the
subsequence.  In list context it yields a list of corresponding
indices, which are represented by 2-element array refs.  See the
L<Algorithm::Diff> manpage for more details.

=back

=head2 EXPORT

ADLCS() and LCSidx().  See Algorithm::Diff for the APIs.

=head1 SEE ALSO

Algorithm::Diff

=head1 AUTHOR

Joe Schaefer, E<lt>joe+cpan@sunstarsys.comE<gt>

=head1 COPYRIGHT AND LICENSE

Copyright 2003 by Joe Schaefer

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.

=cut