package Parse::Highlife::Rule::Optional;
use strict;
use base qw(Parse::Highlife::Rule);
use Parse::Highlife::Utils qw(params);
use Data::Dump qw(dump);
sub new
{
my( $class, @args ) = @_;
my $self = bless Parse::Highlife::Rule->new( @args ), $class;
return $self -> _init( @args );
}
sub _init
{
my( $self, $optional )
= params( \@_,
-optional => '',
);
$self->{'optional'} = $optional;
return $self;
}
sub parse_from_token
{
my( $self, $parser, $tokens, $t ) = @_;
# - turn list of subrules into a single SEQ() rule
# - try to parse SEQ() rule
# - on success: return result, else return failure
my $subrule = $parser->get_rule( $self->{'optional'} );
my $_t = $t;
my ($_status, $_result);
($_t) = $self->_parse_ignored_tokens( $tokens, $_t );
($_status, $_t, $_result) = $subrule->wrap_parse_from_token( $parser, $tokens, $_t );
if( $_status ) {
return (
1,
$_t,
$parser->make_ast_element('group', $self->{'name'}, [ $_result ])
);
}
return (
1,
$t,
$parser->make_ast_element('group', $self->{'name'}, [])
); # always succeeds, since its optional
}
1;