=head1 NAME

Net::LDAP::Filter - representation of LDAP filters

=head1 SYNOPSIS

  use Net::LDAP::Filter;

  $filter = Net::LDAP::Filter->new( $filter_str );

=head1 DESCRIPTION

The B<Net::LDAP::Filter> object lets you directly manipulate LDAP
filters without worrying about the string representation and all the
associated escaping mechanisms.

=head1 CONSTRUCTOR

=over 4

=item new ( [ FILTER ] )

Create a new object.
If FILTER is given, parse it.

=back

=head1 METHODS

=over 4

=item parse ( FILTER )

Parse FILTER, updating the object to represent it.

=item as_string

Return the filter in text form.

=item print ( [ FH ] )

Print the text representation of the filter to FH, or the currently
selected output handle if FH is not given.

=item negate ( )

Logically negate/invert the filter object so that it matches the opposite
set of entries as the original.

Instead of simply negating the text form by surrounding it with the B<not>
operator, the negation is done by recursively applying I<De Morgan's law>.

Here is an example:

 (|(&(cn=A)(cn=B))(|(!(cn=C))(cn=D)))

gets negated to

 (&(|(!(cn=A))(!(cn=B)))(&(cn=C)(!(cn=D))))


=back

=head1 FILTER SYNTAX

Below is the syntax for a filter given in RFC 4515
http://www.ietf.org/rfc/rfc4515.txt

 filter       = "(" filtercomp ")"
 filtercomp   = and / or / not / item
 and          = "&" filterlist
 or           = "|" filterlist
 not          = "!" filter
 filterlist   = 1*filter
 item         = simple / present / substring / extensible
 simple       = attr filtertype value
 filtertype   = equal / approx / greater / less
 equal        = "="
 approx       = "~="
 greater      = ">="
 less         = "<="
 extensible   = attr [":dn"] [":" matchingrule] ":=" value
                / [":dn"] ":" matchingrule ":=" value
 present      = attr "=*"
 substring    = attr "=" [initial] any [final]
 initial      = value
 any          = "*" *(value "*")
 final        = value
 attr         = AttributeDescription from Section 4.1.4 of RFC 4511
 matchingrule = MatchingRuleId from Section 4.1.8 of RFC 4511
 value        = AttributeValue from Section 4.1.5 of RFC 4511


 Special Character encodings
 ---------------------------
    *               \2a, \*
    (               \28, \(
    )               \29, \)
    \               \5c, \\
    NUL             \00

=head1 SEE ALSO

L<Net::LDAP>,
L<Other online documentation|Net::LDAP::RFC>

=head1 ACKNOWLEDGEMENTS

This document is based on a document originally written by Russell Fulton
E<lt>r.fulton@auckland.ac.nzE<gt>.

=head1 AUTHOR

Graham Barr E<lt>gbarr@pobox.comE<gt>

Please report any bugs, or post any suggestions, to the perl-ldap mailing list
E<lt>perl-ldap@perl.orgE<gt>.

=head1 COPYRIGHT

Copyright (c) 1997-2004 Graham Barr. All rights reserved. This program is
free software; you can redistribute it and/or modify it under the same
terms as Perl itself.

=cut