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package Perl::Critic::Policy::ValuesAndExpressions::ProhibitInterpolationOfLiterals;
use 5.010001;
use strict;
use warnings;
use Readonly;
use List::SomeUtils qw(any);
use Perl::Critic::Utils qw{ :characters :severities :data_conversion };
use parent 'Perl::Critic::Policy';
our $VERSION = '1.156';
#-----------------------------------------------------------------------------
Readonly::Scalar my $DESC => q{Useless interpolation of literal string};
Readonly::Scalar my $EXPL => [51];
#-----------------------------------------------------------------------------
sub supported_parameters {
return (
{
name => 'allow',
description =>
'Kinds of delimiters to permit, e.g. "qq{", "qq(", "qq[", "qq/".',
default_string => $EMPTY,
parser => \&_parse_allow,
},
{
name => 'allow_if_string_contains_single_quote',
description =>
q<If the string contains ' characters, allow "" to quote it.>,
default_string => '0',
behavior => 'boolean',
},
);
}
sub default_severity { return $SEVERITY_LOWEST }
sub default_themes { return qw( core pbp cosmetic ) }
sub applies_to { return qw(PPI::Token::Quote::Double
PPI::Token::Quote::Interpolate) }
#-----------------------------------------------------------------------------
Readonly::Scalar my $MAX_SPECIFICATION_LENGTH => 3;
sub _parse_allow {
my ($self, undef, $config_string) = @_;
my @allow;
if (defined $config_string) {
@allow = words_from_string( $config_string );
#Try to be forgiving with the configuration...
for (@allow) {
m{ \A qq }xms || ($_ = 'qq' . $_)
} #Add 'qq'
for (@allow) {
(length $_ <= $MAX_SPECIFICATION_LENGTH) || chop
} #Chop closing char
}
$self->{_allow} = \@allow;
return;
}
#-----------------------------------------------------------------------------
sub violates {
my ( $self, $elem, undef ) = @_;
# Skip if this string needs interpolation
return if _has_interpolation($elem);
# Overlook allowed quote styles
return if any { $elem =~ m{ \A \Q$_\E }xms } @{ $self->{_allow} };
# If the flag is set, allow "I'm here".
if ( $self->{_allow_if_string_contains_single_quote} ) {
return if index ($elem, $QUOTE) >= 0;
}
# Must be a violation
return $self->violation( $DESC, $EXPL, $elem );
}
#-----------------------------------------------------------------------------
sub _has_interpolation {
my $elem = shift;
return $elem =~ m<
(?: \A | [^\\] )
(?: \\{2} )*
(?: [\$\@] \S+ | \\[tnrfbae0xcNLuLUEQ] )
>xmso;
}
1;
__END__
#-----------------------------------------------------------------------------
=pod
=head1 NAME
Perl::Critic::Policy::ValuesAndExpressions::ProhibitInterpolationOfLiterals - Always use single quotes for literal strings.
=head1 AFFILIATION
This Policy is part of the core L<Perl::Critic|Perl::Critic>
distribution.
=head1 DESCRIPTION
Don't use double-quotes or C<qq//> if your string doesn't require
interpolation. This saves the interpreter a bit of work and it lets
the reader know that you really did intend the string to be literal.
print "foobar"; #not ok
print 'foobar'; #ok
print qq/foobar/; #not ok
print q/foobar/; #ok
print "$foobar"; #ok
print "foobar\n"; #ok
print qq/$foobar/; #ok
print qq/foobar\n/; #ok
print qq{$foobar}; #preferred
print qq{foobar\n}; #preferred
Use of double-quotes might be reasonable if the string contains single
quote (') characters:
print "it's me"; # ok, if configuration flag set
=head1 CONFIGURATION
The types of quoting styles to exempt from this policy can be
configured via the C<allow> option. This must be a
whitespace-delimited combination of some or all of the following
styles: C<qq{}>, C<qq()>, C<qq[]>, and C<qq//>.
This is useful because some folks have configured their editor to
apply special syntax highlighting within certain styles of quotes.
For example, you can tweak C<vim> to use SQL highlighting for
everything that appears within C<qq{}> or C<qq[]> quotes. But if
those strings are literal, Perl::Critic will complain. To prevent
this, put the following in your F<.perlcriticrc> file:
[ValuesAndExpressions::ProhibitInterpolationOfLiterals]
allow = qq{} qq[]
The flag C<allow_if_string_contains_single_quote> permits
double-quoted strings if the string contains a single quote (')
character. It defaults to off; to turn it on put the following in
your F<.perlcriticrc> file:
[ValuesAndExpressions::ProhibitInterpolationOfLiterals]
allow_if_string_contains_single_quote = 1
=head1 SEE ALSO
L<Perl::Critic::Policy::ValuesAndExpressions::RequireInterpolationOfMetachars|Perl::Critic::Policy::ValuesAndExpressions::RequireInterpolationOfMetachars>
=head1 AUTHOR
Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>
=head1 COPYRIGHT
Copyright (c) 2005-2021 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
# Local Variables:
# mode: cperl
# cperl-indent-level: 4
# fill-column: 78
# indent-tabs-mode: nil
# c-indentation-style: bsd
# End:
# ex: set ts=8 sts=4 sw=4 tw=78 ft=perl expandtab shiftround :
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