package String::LCSS::Fast; use 5.006; use strict; use warnings; use Algorithm::Diff qw(traverse_sequences); require Exporter; use vars qw( @ISA @EXPORT_OK $VERSION ); our @ISA = qw(Exporter); @EXPORT_OK = qw( LCSS CSS CSS_Sorted ); $VERSION = '0.01'; sub _tokenize { [split //, $_[0]] } sub CSS { my $is_array = ref $_[0] eq 'ARRAY' ? 1 : 0; my $sort = $_[2]; my ( $seq1, $seq2, @match, $from_match ); my $i = 0; if ( $is_array ) { $seq1 = $_[0]; $seq2 = $_[1]; traverse_sequences( $seq1, $seq2, { MATCH => sub { push @{$match[$i]}, $seq1->[$_[0]]; $from_match = 1 }, DISCARD_A => sub { do{$i++; $from_match = 0} if $from_match }, DISCARD_B => sub { do{$i++; $from_match = 0} if $from_match }, }); } else { $seq1 = _tokenize($_[0]); $seq2 = _tokenize($_[1]); traverse_sequences( $seq1, $seq2, { MATCH => sub { $match[$i] .= $seq1->[$_[0]]; $from_match = 1 }, DISCARD_A => sub { do{$i++; $from_match = 0} if $from_match }, DISCARD_B => sub { do{$i++; $from_match = 0} if $from_match }, }); } return \@match; } sub CSS_Sorted { my $match = CSS(@_); if ( ref $_[0] eq 'ARRAY' ) { @$match = map{$_->[0]}sort{$b->[1]<=>$a->[1]}map{[$_,scalar(@$_)]}@$match } else { @$match = map{$_->[0]}sort{$b->[1]<=>$a->[1]}map{[$_,length($_)]}@$match } return $match; } sub LCSS { my $is_array = ref $_[0] eq 'ARRAY' ? 1 : 0; my $css = CSS(@_); my $index; my $length = 0; if ( $is_array ) { for( my $i = 0; $i < @$css; $i++ ) { next unless @{$css->[$i]}>$length; $index = $i; $length = @{$css->[$i]}; } } else { for( my $i = 0; $i < @$css; $i++ ) { next unless length($css->[$i])>$length; $index = $i; $length = length($css->[$i]); } } return $css->[$index]; } 1; __END__ =head1 NAME String::LCSS::Fast - Perl extension for getting the Longest Common SubString =head1 SYNOPSIS use String::LCSS::Fast qw( LCSS CSS CSS_Sorted ); =head1 DESCRIPTION This module uses Algoritm::Diff to implement LCSS and is orders of magnitude faster than String::LCSS. =head1 METHODS =head2 LCSS Returns the longest common sub string. If there may be more than one and it matters use CSS instead. my $lcss_ary_ref = LCSS( \@SEQ1, \@SEQ2 ); # ref to array my $lcss_string = LCSS( $STR1, $STR2 ); # string =head2 CSS Returns all the common sub strings, unsorted. my $css_ary_ref = CSS( \@SEQ1, \@SEQ2 ); # ref to array of arrays my $css_str_ref = CSS( $STR1, $STR2 ); # ref to array of strings =head2 CSS_Sorted Returns all the common sub strings, sorted from longest to shortest my $css_ary_ref = CSS( \@SEQ1, \@SEQ2 ); # ref to array of arrays my $css_str_ref = CSS( $STR1, $STR2 ); # ref to array of strings =head1 EXPORT None by default. =head1 AUTHOR Dr James Freeman =head1 SEE ALSO L. =cut