package Set::Intersection;
use warnings;
use strict;
=head1 NAME
Set::Intersection - provides an API to get intersection (of set theory) of ARRAYs.
=head1 VERSION
Version 0.04;
=cut
our $VERSION = '0.04';
=head1 SYNOPSIS
use Set::Intersection;
my @arr1 = qw/3 1 4 1 5 9/;
my @arr2 = qw/1 7 3 2 0 5/;
my @intersection = get_intersection(\@arr1, \@arr2);
# got (1, 3, 5) in @intersection
=head1 EXPORT
get_intersection
=cut
require Exporter;
our @ISA = qw/Exporter/;
our @EXPORT = qw/get_intersection/;
=head1 FUNCTIONS
=head2 C<get_intersection()>
get_intersection([\%options,] [\@ARRAY[, \@ARRAY[, ...]]]);
Returns intersection set (as LIST) of all ARRAYs.
=over 4
=item *
The result LIST is uniqued and unordered.
=item *
If no ARRAYs are passed, the result LIST is empty.
=item *
If only one ARRAY is passed, the result LIST is same as that passed. (In this
case, elements won't be uniqued nor will the order bechanged.)
=item *
If you have C<undef> in any LIST, you'll be warned.
=back
=head3 C<%options>
-preordered => BOOLEAN
To reduce calculation time, C<get_intersection()> sorts ARRAYs
by their length before calculating intersections.
This option tells that order of ARRAYs are well done,
and calculation of intersection will be based on left most ARRAY.
=cut
my %_default_opts = (
-preordered => 0,
);
sub get_intersection
{
my %opts;
if ( ref($_[0]) =~ m{^HASH} ) {
%opts = (%_default_opts, %{$_[0]});
shift;
}
my @arrs = @_;
return () if !@arrs;
return @{$arrs[0]} if @arrs == 1;
@arrs = sort { @$a <=> @$b } @arrs if !$opts{-preordered};
my $head = shift @arrs;
_intersection($head, @arrs);
}
sub _intersection
{
my ($head, @left) = @_;
my %h = map { $_ => undef } @$head;
for my $l ( @left ) {
%h = map { $_ => undef } grep { exists $h{$_} } @$l;
}
keys %h;
}
=head1 SEE ALSO
List::Compare, Set::Object
=head1 AUTHOR
turugina, C<< <turugina at cpan.org> >>
=head1 BUGS
Please report any bugs or feature requests to C<bug-list-intersection at rt.cpan.org>, or through
the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Set-Intersection>. I will be notified, and then you'll
automatically be notified of progress on your bug as I make changes.
=head1 SUPPORT
You can find documentation for this module with the perldoc command.
perldoc Set::Intersection
You can also look for information at:
=over 4
=item * RT: CPAN's request tracker
L<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Set-Intersection>
=item * AnnoCPAN: Annotated CPAN documentation
L<http://annocpan.org/dist/Set-Intersection>
=item * CPAN Ratings
L<http://cpanratings.perl.org/d/Set-Intersection>
=item * Search CPAN
L<http://search.cpan.org/dist/Set-Intersection/>
or
L<https://metacpan.org/pod/Set::Intersection>
=back
=head1 ACKNOWLEDGEMENTS
=head1 COPYRIGHT & LICENSE
Copyright 2009 turugina, all rights reserved.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
=cut
1; # End of Set::Intersection