NAME

Set::Light - (memory efficient) unordered set of strings

VERSION

version 0.95

SYNOPSIS

use Set::Light;

my $set = Set::Light->new( qw/foo bar baz/ );

if (!$set->is_empty())
{
  print "Set has ", $set->size(), " elements.\n";
  for (qw/umpf foo bar baz bam/)
  {
      print "Set does ";
      print " not " unless $set->has($_);
      print "contain '$_'.\n";
  }
}

DESCRIPTION

Set::Light implements an unordered set of strings. Set::Light currently uses a hash underneath, and each key of the hash points to the same scalar, thus saving memory per item.

Why not use a hash?

Usually you would use a hash to keep track of a list of items like:

my %SEEN;

...

if (!$SEEN->{$item}++)
{
  # haven't seen item before
}

While this is very fast (both on inserting items, as well as looking them up), it uses quite a lot of memory, since each key in %SEEN needs one scalar.

Why not use Set::Object or Set::Scalar?

These use even more memory and/or are slower than an ordinary hash.

METHODS

new

my $set = Set::Light->new( \%opts, @members );

Creates a new Set::Light object. An optionally passed hash reference can contain options.

Any members passed to the constructor will be inserted.

Currently no options are supported.

insert

$set->insert( $string );
$set->insert( @strings );

Inserts one or more strings into the set. Returns the number of insertions it really did. Elements that are already contained in the set do not get inserted twice. So:

use Set::Light;

my $set = Set::Light->new();
print $set->insert('foo');              # 1
print $set->insert('foo');              # 0
print $set->insert('bar','baz','foo');  # 2     (foo already inserted)

is_empty

if (!$set->is_empty()) { ... }

Returns true if the set is empty (has zero elements).

is_null

This is an alias to "is_empty".

size

my $elems = $set->size();

Returns the number of elements in the set.

has

if ($set->has($member)) { ... }

Returns true if the set contains the string $member.

contains

This is an alias for "has".

exists

This is an alias for "has".

delete

$set->delete( $string );
$set->delete( @strings );

Deletes one or more strings from the set. Returns the number of deletions it really did. Elements that are not contained in the set cannot be deleted. So:

use Set::Light;

my $set = Set::Light->new();
print $set->insert('foo','bar');      # 2
print $set->delete('foo','foo');      # 1     (only once deleted)
pprint $set->delete('bar','foo');     # 1     (only once deleted)

remove

This is an alias for "delete".

members

my @members = $set->members;

This returns an array of set members in an unsorted array.

This was added in v0.91.

SEE ALSO

Set::Object, Set::Scalar.

SOURCE

The development version is on github at https://github.com/robrwo/Set-Light and may be cloned from git://github.com/robrwo/Set-Light.git

BUGS

Please report any bugs or feature requests on the bugtracker website https://github.com/robrwo/Set-Light/issues

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.

AUTHOR

Tels nospam-abuse@bloodgate.com

CONTRIBUTOR

Robert Rothenberg rrwo@cpan.org

COPYRIGHT AND LICENSE

This software is copyright (c) 2004-2008, 2019-2021 by Tels.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.