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##############################################################################
#      $URL: http://perlcritic.tigris.org/svn/perlcritic/trunk/distributions/Perl-Critic/lib/Perl/Critic/Policy/ValuesAndExpressions/ProhibitMismatchedOperators.pm $
#     $Date: 2010-11-30 21:05:15 -0600 (Tue, 30 Nov 2010) $
#   $Author: clonezone $
# $Revision: 3998 $
##############################################################################
package Perl::Critic::Policy::ValuesAndExpressions::ProhibitMismatchedOperators;
use 5.006001;
use strict;
use warnings;
use Readonly;
use Perl::Critic::Utils qw{ :booleans :severities };
use base 'Perl::Critic::Policy';
our $VERSION = '1.110_001';
#-----------------------------------------------------------------------------
Readonly::Scalar my $DESC => q<Mismatched operator>;
Readonly::Scalar my $EXPL => q<Numeric/string operators and operands should match>;
# token compatibility [ numeric, string ]
Readonly::Hash my %TOKEN_COMPATIBILITY => (
    'PPI::Token::Number' => [$TRUE,  $FALSE],
    'PPI::Token::Symbol' => [$TRUE,  $TRUE ],
    'PPI::Token::Quote'  => [$FALSE, $TRUE ],
);
Readonly::Hash my %FILE_OPERATOR_COMPATIBILITY =>
    map {; "-$_" => [$TRUE, $FALSE] }
        qw< r w x o R W X O e z s f d l p S b c t u g k T B M A >;
Readonly::Scalar my $TOKEN_COMPATIBILITY_INDEX_NUMERIC => 0;
Readonly::Scalar my $TOKEN_COMPATIBILITY_INDEX_STRING  => 1;
Readonly::Hash my %OPERATOR_TYPES => (
    # numeric
    (
        map { $_ => $TOKEN_COMPATIBILITY_INDEX_NUMERIC }
            qw[ == != > >= < <= + - * / += -= *= /= ]
    ),
    # string
    map { $_ => $TOKEN_COMPATIBILITY_INDEX_STRING }
        qw< eq ne lt gt le ge . .= >,
);
#-----------------------------------------------------------------------------
sub supported_parameters { return ()                     }
sub default_severity     { return $SEVERITY_MEDIUM       }
sub default_themes       { return qw< core bugs >        }
sub applies_to           { return 'PPI::Token::Operator' }
#-----------------------------------------------------------------------------
sub violates {
    my ($self, $elem) = @_;
    my $elem_text = $elem->content();
    return if not exists $OPERATOR_TYPES{$elem_text};
    my $leading_operator = $self->_get_potential_leading_operator($elem)
        or return;
    my $next_elem = $elem->snext_sibling() or return;
    if ( $next_elem->isa('PPI::Token::Operator') ) {
        $elem_text .= $next_elem->content();
        $next_elem = $next_elem->snext_sibling();
    }
    return if not exists $OPERATOR_TYPES{$elem_text};
    my $operator_type = $OPERATOR_TYPES{$elem_text};
    my $leading_operator_compatibility =
        $self->_get_token_compatibility($leading_operator);
    my $next_compatibility = $self->_get_token_compatibility($next_elem);
    return if
            (
                    ! defined $leading_operator_compatibility
                ||  $leading_operator_compatibility->[$operator_type]
            )
        &&  (
                    ! defined $next_compatibility
                ||  $next_compatibility->[$operator_type]
            );
    return if
            $operator_type
        &&  defined $leading_operator_compatibility
        &&  ! $leading_operator_compatibility->[$operator_type]
        &&  $self->_have_stringy_x($leading_operator); # RT 54524
    return $self->violation($DESC, $EXPL, $elem);
}
#-----------------------------------------------------------------------------
sub _get_token_compatibility {
    my ($self, $elem) = @_;
    return $FILE_OPERATOR_COMPATIBILITY{ $elem->content() }
        if $self->_is_file_operator($elem);
    for my $class (keys %TOKEN_COMPATIBILITY) {
        return $TOKEN_COMPATIBILITY{$class} if $elem->isa($class);
    }
    return;
}
#-----------------------------------------------------------------------------
sub _have_stringy_x {
    my ($self, $elem) = @_;
    return if not $elem;
    my $prev_oper = $elem->sprevious_sibling() or return;
    return if not $prev_oper->isa('PPI::Token::Operator');
    return if 'x' ne $prev_oper->content();
    return !! $prev_oper->sprevious_sibling();
}
#-----------------------------------------------------------------------------
sub _get_potential_leading_operator {
    my ($self, $elem) = @_;
    my $previous_element = $elem->sprevious_sibling() or return;
    if ( $self->_get_token_compatibility($previous_element) ) {
        my $previous_sibling = $previous_element->sprevious_sibling();
        if (
            $previous_sibling and $self->_is_file_operator($previous_sibling)
        ) {
            $previous_element = $previous_sibling;
        }
    }
    return $previous_element;
}
#-----------------------------------------------------------------------------
sub _is_file_operator {
    my ($self, $elem) = @_;
    return if not $elem;
    return if not $elem->isa('PPI::Token::Operator');
    return !! $FILE_OPERATOR_COMPATIBILITY{ $elem->content() }
}
1;
__END__
#-----------------------------------------------------------------------------
HideShow 53 lines of Pod
=pod
=head1 NAME
Perl::Critic::Policy::ValuesAndExpressions::ProhibitMismatchedOperators - Don't mix numeric operators with string operands, or vice-versa.
=head1 AFFILIATION
This Policy is part of the core L<Perl::Critic|Perl::Critic>
distribution.
=head1 DESCRIPTION
Using the wrong operator type for a value can obscure coding intent
and possibly lead to subtle errors.  An example of this is mixing a
string equality operator with a numeric value, or vice-versa.
    if ($foo == 'bar') {}     #not ok
    if ($foo eq 'bar') {}     #ok
    if ($foo eq 123) {}       #not ok
    if ($foo == 123) {}       #ok
=head1 CONFIGURATION
This Policy is not configurable except for the standard options.
=head1 NOTES
If L<warnings|warnings> are enabled, the Perl interpreter usually
warns you about using mismatched operators at run-time.  This Policy
does essentially the same thing, but at author-time.  That way, you
can find out about them sooner.
=head1 AUTHOR
Peter Guzis <pguzis@cpan.org>
=head1 COPYRIGHT
Copyright (c) 2006-2010 Peter Guzis.  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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