package Perl::Critic::Policy::RegularExpressions::RequireLineBoundaryMatching;

use 5.006001;
use strict;
use warnings;
use Readonly;

use Perl::Critic::Utils qw{ :severities };

use base 'Perl::Critic::Policy';

our $VERSION = '1.125';

#-----------------------------------------------------------------------------

Readonly::Scalar my $DESC => q{Regular expression without "/m" flag};
Readonly::Scalar my $EXPL => [ 237 ];

#-----------------------------------------------------------------------------

sub supported_parameters { return ()                    }
sub default_severity     { return $SEVERITY_LOW         }
sub default_themes       { return qw(core pbp cosmetic) }
sub applies_to           { return qw(PPI::Token::Regexp::Match
                                     PPI::Token::Regexp::Substitute
                                     PPI::Token::QuoteLike::Regexp) }

#-----------------------------------------------------------------------------

sub violates {
    my ( $self, $elem, $doc ) = @_;

    my $re = $doc->ppix_regexp_from_element( $elem )
        or return;
    $re->modifier_asserted( 'm' )
        or return $self->violation( $DESC, $EXPL, $elem );

    return; #ok!;
}

1;

__END__

#-----------------------------------------------------------------------------

=pod

=head1 NAME

Perl::Critic::Policy::RegularExpressions::RequireLineBoundaryMatching - Always use the C</m> modifier with regular expressions.


=head1 AFFILIATION

This Policy is part of the core L<Perl::Critic|Perl::Critic>
distribution.


=head1 DESCRIPTION

Folks coming from a C<sed> or C<awk> background tend to assume that
C<'$'> and C<'^'> match the beginning and end of the line, rather than
then beginning and end of the string.  Adding the '/m' flag to your
regex makes it behave as most people expect it should.

    my $match = m{ ^ $pattern $ }x;  #not ok
    my $match = m{ ^ $pattern $ }xm; #ok


=head1 CONFIGURATION

This Policy is not configurable except for the standard options.


=head1 NOTES

For common regular expressions like e-mail addresses, phone numbers,
dates, etc., have a look at the L<Regexp::Common|Regexp::Common> module.
Also, be cautions about slapping modifier flags onto existing regular
expressions, as they can drastically alter their meaning.  See
L<http://www.perlmonks.org/?node_id=484238> for an interesting
discussion on the effects of blindly modifying regular expression
flags.


=head1 AUTHOR

Jeffrey Ryan Thalhammer  <jeff@imaginative-software.com>


=head1 COPYRIGHT

Copyright (c) 2005-2011 Imaginative Software Systems. All rights reserved.

This program is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.  The full text of this license
can be found in the LICENSE file included with this module.

=cut

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