07-24-2008
Interesting and thoughtful question. You use "(" and ")" to mark (remember) a pattern and recall the remembered pattern with "\" followed by a single digit (back reference).
In your particular case, "(.)\1" means remember a character and recall the character.
You can extend this method to find words with multiple double letters. '(.)\1(.)\2(.)\3' will match any word with three double letters, e.g. bookkeeper.
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LEARN ABOUT DEBIAN
datetime::format::builder::parser::regex
DateTime::Format::Builder::Parser::Regex(3pm) User Contributed Perl Documentation DateTime::Format::Builder::Parser::Regex(3pm)
NAME
DateTime::Format::Builder::Parser::Regex - Regex based date parsing
SYNOPSIS
my $parser = DateTime::Format::Builder->create_parser(
regex => qr/^(dddd)(dd)(dd)T(dd)(dd)(dd)$/,
params => [ qw( year month day hour minute second ) ],
);
SPECIFICATION
In addition to the common keys, "Regex" supports:
o regex is a regular expression that should capture elements of the datetime string. This is a required element. This is the key whose
presence indicates it's a specification that belongs to this class.
o params is an arrayref of key names. The captures from the regex are mapped to these ($1 to the first element, $2 to the second, and so
on) and handed to "DateTime->new()". This is a required element.
o extra is a hashref of extra arguments you wish to give to "DateTime->new()". For example, you could set the "year" or "time_zone" to
defaults:
extra => { year => 2004, time_zone => "Australia/Sydney" },
o constructor is either an arrayref or a coderef. If an arrayref then the first element is a class name or object, and the second element
is a method name (or coderef since Perl allows that sort of thing). The arguments to the call are anything in $p and anything given in
the "extra" option above.
If only a coderef is supplied, then it is called with arguments of $self, $p and "extra".
In short:
$self->$coderef( %$p, %{ $self->{extra} } );
The method is expected to return a valid DateTime object, or undef in event of failure, but can conceivably return anything it likes.
So long as it's 'true'.
THANKS
See the main module's section.
SUPPORT
Support for this module is provided via the datetime@perl.org email list. See http://lists.perl.org/ for more details.
Alternatively, log them via the CPAN RT system via the web or email:
http://perl.dellah.org/rt/dtbuilder
bug-datetime-format-builder@rt.cpan.org
This makes it much easier for me to track things and thus means your problem is less likely to be neglected.
LICENCE AND COPYRIGHT
Copyright X Iain Truskett, 2003. All rights reserved.
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.000 or,
at your option, any later version of Perl 5 you may have available.
The full text of the licences can be found in the Artistic and COPYING files included with this module, or in perlartistic and perlgpl as
supplied with Perl 5.8.1 and later.
AUTHOR
Iain Truskett <spoon@cpan.org>
SEE ALSO
"datetime@perl.org" mailing list.
http://datetime.perl.org/
perl, DateTime, DateTime::Format::Builder
perl v5.10.1 2010-03-14 DateTime::Format::Builder::Parser::Regex(3pm)