##############################################################################
#      $URL: http://perlcritic.tigris.org/svn/perlcritic/trunk/Perl-Critic/lib/Perl/Critic/Policy/ControlStructures/ProhibitDeepNests.pm $
#     $Date: 2008-07-03 10:19:10 -0500 (Thu, 03 Jul 2008) $
#   $Author: clonezone $
# $Revision: 2489 $
##############################################################################

package Perl::Critic::Policy::ControlStructures::ProhibitDeepNests;

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

use Perl::Critic::Utils qw{ :severities };
use base 'Perl::Critic::Policy';

our $VERSION = '1.088';

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

Readonly::Scalar my $DESC => q{Code structure is deeply nested};
Readonly::Scalar my $EXPL => q{Consider refactoring};

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

sub supported_parameters {
    return (
        {
            name            => 'max_nests',
            description     => 'The maximum number of nested constructs to allow.',
            default_string  => '5',
            behavior        => 'integer',
            integer_minimum => 1,
        },
    );
}

sub default_severity { return $SEVERITY_MEDIUM                }
sub default_themes   { return qw(core maintenance complexity) }
sub applies_to       { return 'PPI::Statement::Compound'      }

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

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

    my $nest_count = 1;  #For _this_ element
    my $parent = $elem;

    while ( $parent = $parent->parent() ){
        if( $parent->isa('PPI::Statement::Compound') ) {
            $nest_count++;
        }
    }

    if ( $nest_count > $self->{_max_nests} ) {
        return $self->violation( $DESC, $EXPL, $elem );
    }
    return;    #ok!
}


1;

__END__


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

=pod

=for stopwords refactored

=head1 NAME

Perl::Critic::Policy::ControlStructures::ProhibitDeepNests - Don't write deeply nested loops and conditionals.

=head1 AFFILIATION

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


=head1 DESCRIPTION

Deeply nested code is often hard to understand and may be a sign that
it needs to be refactored.  There are several good books on how to
refactor code.  I like Martin Fowler's "Refactoring: Improving The
Design of Existing Code".


=head1 CONFIGURATION

The maximum number of nested control structures can be configured via a value
for C<max_nests> in a F<.perlcriticrc> file.  Each for-loop, if-else, while,
and until block is counted as one nest.  Postfix forms of these constructs are
not counted.  The default maximum is 5.  Customization in a F<.perlcriticrc>
file looks like this:

 [ControlStructures::ProhibitDeepNests]
 max_nests = 3

=head1 AUTHOR

Jeffrey Ryan Thalhammer <thaljef@cpan.org>

=head1 COPYRIGHT

Copyright (c) 2005-2008 Jeffrey Ryan Thalhammer.  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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