=head1 NAME

PPIx::Regexp::Structure::Switch - Represent a switch

=head1 SYNOPSIS

 use PPIx::Regexp::Dumper;
 PPIx::Regexp::Dumper->new( 'qr{(?(1)foo|bar)}smx' )
     ->print();

=head1 INHERITANCE

C<PPIx::Regexp::Structure::Switch> is a
L<PPIx::Regexp::Structure|PPIx::Regexp::Structure>.

C<PPIx::Regexp::Structure::Switch> has no descendants.

=head1 DESCRIPTION

This class represents a switch, or conditional expression. The condition
will be the first child.

=head1 METHODS

This class provides no public methods beyond those provided by its
superclass.

This class provides the following public methods. Methods not documented
here are private, and unsupported in the sense that the author reserves
the right to change or remove them without notice.

=cut

package PPIx::Regexp::Structure::Switch;

use strict;
use warnings;

use base qw{ PPIx::Regexp::Structure };

use PPIx::Regexp::Constant qw{
    MINIMUM_PERL
    STRUCTURE_UNKNOWN
    TOKEN_UNKNOWN
};

our $VERSION = '0.020';

=begin comment

sub perl_version_introduced {
    my ( $self ) = @_;
    my $condition = $self->child( 0 ) or return;
    $condition->isa( 'PPIx::Regexp::Structure' )
	and return MINIMUM_PERL;
    my $content = $condition->content();
    $content =~ m/ \( \d+ \) /smx and return MINIMUM_PERL;
    return '5.009005';
}

=end comment

=cut

sub __PPIX_LEXER__finalize {
    my ( $self ) = @_;

    # Assume no errors.
    my $rslt = 0;

    # Number of allowed alternations not known yet.
    my $alternations;

    # If we are a valid switch, the first child is the condition. Make
    # sure we have a first child and that it is of the expected class.
    # If it is, determine how many alternations are allowed.
    if ( my $condition = $self->child( 0 ) ) {
	foreach my $class ( qw{
	    PPIx::Regexp::Structure::Assertion
	    PPIx::Regexp::Structure::Code
	    PPIx::Regexp::Token::Condition
	    } ) {
	    $condition->isa( $class ) or next;
	    $alternations = $condition->content() eq '(DEFINE)' ? 0 : 1;
	    last;
	}
    }

    if ( defined $alternations ) {
	# If we figured out how many alternations were allowed, count
	# them, changing surplus ones to the unknown token.
	foreach my $kid ( $self->children () ) {
	    $kid->isa( 'PPIx::Regexp::Token::Operator' ) or next;
	    $kid->content() eq '|' or next;
	    --$alternations >= 0 and next;
	    bless $kid, TOKEN_UNKNOWN;
	    $rslt++;
	}
    } else {
	# If we could not figure out how many alternations were allowed,
	# it means we did not understand our condition. Rebless
	# ourselves to the unknown structure and count a parse failure.
	bless $self, STRUCTURE_UNKNOWN;
	$rslt++;
    }

    # Delegate to the superclass to finalize our children, now that we
    # have finished messing with them.
    $rslt = $self->SUPER::__PPIX_LEXER__finalize();

    return $rslt;
}

1;

__END__

=head1 SUPPORT

Support is by the author. Please file bug reports at
L<http://rt.cpan.org>, or in electronic mail to the author.

=head1 AUTHOR

Thomas R. Wyant, III F<wyant at cpan dot org>

=head1 COPYRIGHT AND LICENSE

Copyright (C) 2009-2011 by Thomas R. Wyant, III

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl 5.10.0. For more details, see the full text
of the licenses in the directory LICENSES.

This program is distributed in the hope that it will be useful, but
without any warranty; without even the implied warranty of
merchantability or fitness for a particular purpose.

=cut

# ex: set textwidth=72 :
