use Exporter 'import';
-our $VERSION = '1.01';
+our $VERSION = '1.02';
our @EXPORT_OK = qw(rangematch);
sub new {
- my ($class, $values) = @_;
- bless [sort map { s/[^a-z]/./g; $_ } @$values], $class;
+ my ($class, $options) = @_;
+ $options ||= {};
+ bless $options, $class;
}
sub ranges {
my $self = shift;
+ my @rows = sort map { s/[^a-z]/./g; $_ } @{ shift() };
my $options = shift || {};
+ $options->{$_} //= $self->{$_} for keys %$self;
+
my $pagesize = $options->{pagesize} || 50;
my $context = $options->{context } // 1 + ($pagesize >> 4);
my $length = $options->{length } || 4;
- my $pages = $options->{pages } || 1 + int $#$self / $pagesize;
+ my $pages = $options->{pages } || 1 + int($#rows / $pagesize);
+
+ $pagesize = $pages >= @rows ? 1 : @rows / $pages;
+ my $shrunk = 0;
+ my $enlarged = 0;
- $pagesize = @$self / $pages;
- my $offset = $pagesize + .5;
- my $penalty = 0;
my @links = ('');
- while ($offset < @$self) {
- my $link = substr $self->[$offset], 0, $length;
+ for (my $offset = $pagesize + .5; $offset < @rows; $offset += $pagesize) {
+ my $link = substr $rows[$offset], 0, $length;
if ($context) {
- if ($offset > $context - 1 + $penalty) {
- # take a value slightly before the current offset
- my $before = $self->[$offset - $context - 1 + $penalty];
+ my $lookbehind = -$context + $shrunk;
+ my $lookahead = $context - $enlarged;
+ $shrunk = $enlarged = 0;
+
+ # take a value slightly before the current offset
+ if ((my $before = $offset + $lookbehind) > 0) {
# see how much of it matches the current link
my $trim = 1;
- for my $match (split //, $before) {
+ for my $match (split //, $rows[$before - 1]) {
scalar $link =~ /\G\Q$match/g or last;
$trim++;
}
# truncate link upto where the earlier value starts to differ
- substr($link, $trim) = '' unless $trim > length $link;
+ if ($trim < length $link) {
+ substr($link, $trim) = '';
+ for (reverse $before .. $offset - 1) {
+ $rows[$_] =~ /^\Q$link/ or last;
+ $enlarged++;
+ }
+ }
}
- $penalty = 0;
- if ($offset + $context < $#$self) {
- # take a value after the current offset
- my $after = $self->[$offset + $context];
+ # take a value after the current offset
+ if ((my $after = $offset + $lookahead) < $#rows) {
# see how much of it matches the current link
my $trim = 1;
- for my $match (split //, $after) {
+ pos $link = 0;
+ for my $match (split //, $rows[$after]) {
scalar $link =~ /\G\Q$match/g or last;
$trim++;
}
# use this link if it's shorter
if ($trim < length $link) {
- $link = substr $after, 0, $trim;
- for ($offset .. $#$self) {
- last if $self->[$offset + $penalty] =~ /^\Q$link/;
- $penalty++;
+ $enlarged = 0;
+ for ($offset + 1 .. $after) {
+ my $prefix = substr $rows[$_], 0, $trim;
+ # advance lookbehind offset on the next page
+ $shrunk++;
+ next if $link =~ /^\Q$prefix/;
+ $link = $prefix;
+ last;
}
}
}
}
- push @links, $link;
- $offset += $pagesize;
+ push @links, $link unless $links[-1] eq $link;
}
- use List::MoreUtils 'uniq';
- @links = uniq @links;
+ # add range end to each link
for my $i (0 .. $#links - 1) {
- my ($link, $lastchar) = $links[$i + 1] =~ /(.*)(.)/;
- $link .= $lastchar le 'a' ? '.' : chr( ord($lastchar) - 1 );
- next if $link eq $links[$i] and $i;
- $links[$i] .= '-'.$link;
+ # end at start of next value with the last character decremented
+ my $next = $links[$i + 1];
+ $next =~ s{(.)$}{ $1 le 'a' ? '.' : chr( ord($1) - 1 ) }e;
+ # amend range if it's ahead
+ $links[$i] .= '-'.$next unless $next eq $links[$i];
}
+ # final value takes the rest
$links[-1] .= '-';
return \@links;
=head1 SYNOPSIS
use List::Index;
- my $index = List::Index->new(\@values);
- my @pages = $index->ranges({pagesize => 50});
+ my $index = List::Index->new({ pagesize => 50 });
+ my @pages = $index->ranges(\@values);
say "<a href='?q=$_'>$_</a>" for @pages;
use List::Index 'rangematch';