package HTML::Widget::Constraint::DependOn;

use warnings;
use strict;
use base 'HTML::Widget::Constraint';

=head1 NAME

HTML::Widget::Constraint::DependOn - DependOn Constraint

=head1 SYNOPSIS

    my $c = $widget->constraint( 'DependOn', 'foo', 'bar' );

=head1 DESCRIPTION

If the first field listed is filled in, all of the others are required.

=head1 METHODS

=head2 $self->process( $widget, $params )

=cut

sub process {
    my ( $self, $w, $params ) = @_;
    my $results = [];
    my @names   = @{ $self->names };
    my $first   = shift @names;
    
    return [] if ! exists $params->{$first};
    
    for my $name ( @names ) {
        push @$results,
          HTML::Widget::Error->new(
            { name => $name, message => $self->mk_message } )
          if $self->not ? $params->{$name} : !$params->{$name};
    }
    
    return $results;
}

=head1 AUTHOR

Carl Franks, C<cfranks@cpan.org>

=head1 LICENSE

This library is free software, you can redistribute it and/or modify it under
the same terms as Perl itself.

=cut

1;