/usr/share/perl5/RDF/Query/Plan/SubSelect.pm is in librdf-query-perl 2.918-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# -----------------------------------------------------------------------------
=head1 NAME
RDF::Query::Plan::SubSelect - Executable query plan for sub-select queries.
=head1 VERSION
This document describes RDF::Query::Plan::SubSelect version 2.918.
=head1 METHODS
Beyond the methods documented below, this class inherits methods from the
L<RDF::Query::Plan> class.
=over 4
=cut
package RDF::Query::Plan::SubSelect;
use strict;
use warnings;
use base qw(RDF::Query::Plan);
use Data::Dumper;
use Scalar::Util qw(blessed);
use Storable qw(store_fd fd_retrieve);
use URI::Escape;
use RDF::Query::Error qw(:try);
use RDF::Query::ExecutionContext;
use RDF::Query::VariableBindings;
######################################################################
our ($VERSION);
BEGIN {
$VERSION = '2.918';
}
######################################################################
=item C<< new ( $query, [ \%logging_keys ] ) >>
Returns a new SubSelect query plan object. C<<$query>> is a RDF:Query object
representing a SELECT query.
=cut
sub new {
my $class = shift;
my $query = shift;
my $plan = shift;
unless (blessed($plan) and $plan->isa('RDF::Query::Plan')) {
Carp::confess;
}
my $keys = {};
my $self = $class->SUPER::new( $query, $plan );
$self->[0]{referenced_variables} = [ $query->variables ];
$self->[0]{logging_keys} = $keys;
return $self;
}
=item C<< execute ( $execution_context ) >>
=cut
sub execute ($) {
my $self = shift;
my $context = shift;
$self->[0]{delegate} = $context->delegate;
if ($self->state == $self->OPEN) {
throw RDF::Query::Error::ExecutionError -text => "SUBSELECT plan can't be executed while already open";
}
my $l = Log::Log4perl->get_logger("rdf.query.plan.subselect");
$l->trace("executing subselect");
my $plan = $self->plan;
$l->trace("subselect plan: " . $plan->sse);
my $iter = $plan->execute( $context );
if ($iter) {
$self->[0]{iter} = $iter;
$self->[0]{'open'} = 1;
$self->[0]{'count'} = 0;
$self->[0]{logger} = $context->logger;
$self->state( $self->OPEN );
} else {
warn "no iterator in execute()";
}
$self;
}
=item C<< next >>
=cut
sub next {
my $self = shift;
unless ($self->state == $self->OPEN) {
throw RDF::Query::Error::ExecutionError -text => "next() cannot be called on an un-open SERVICE";
}
my $l = Log::Log4perl->get_logger("rdf.query.plan.subselect");
return undef unless ($self->[0]{'open'});
my $iter = $self->[0]{iter};
my $result = $iter->next;
return undef unless $result;
$l->trace("- got subselect result $result");
$self->[0]{'count'}++;
my $row = RDF::Query::VariableBindings->new( $result );
if (my $d = $self->delegate) {
$d->log_result( $self, $row );
}
return $row;
};
=item C<< close >>
=cut
sub close {
my $self = shift;
unless ($self->state == $self->OPEN) {
throw RDF::Query::Error::ExecutionError -text => "close() cannot be called on an un-open SERVICE";
}
my $plan = $self->plan;
if (defined($plan)) {
$plan->close();
}
delete $self->[0]{iter};
delete $self->[0]{args};
delete $self->[0]{count};
$self->SUPER::close();
}
=item C<< query >>
Returns the sub-select query object.
=cut
sub query {
my $self = shift;
return $self->[1];
}
=item C<< plan >>
Returns the sub-select query plan object.
=cut
sub plan {
my $self = shift;
return $self->[2];
}
=item C<< distinct >>
Returns true if the pattern is guaranteed to return distinct results.
=cut
sub distinct {
my $self = shift;
# XXX this could be set at construction time, if we want to trust the remote
# XXX endpoint to return DISTINCT results (when appropriate).
return 0;
}
=item C<< ordered >>
Returns true if the pattern is guaranteed to return ordered results.
=cut
sub ordered {
my $self = shift;
# XXX this could be set at construction time, if we want to trust the remote
# XXX endpoint to return ORDERED results (when appropriate).
return 0;
}
=item C<< plan_node_name >>
Returns the string name of this plan node, suitable for use in serialization.
=cut
sub plan_node_name {
return 'subselect';
}
=item C<< plan_prototype >>
Returns a list of scalar identifiers for the type of the content (children)
nodes of this plan node. See L<RDF::Query::Plan> for a list of the allowable
identifiers.
=cut
sub plan_prototype {
my $self = shift;
return qw(P);
}
=item C<< plan_node_data >>
Returns the data for this plan node that corresponds to the values described by
the signature returned by C<< plan_prototype >>.
=cut
sub plan_node_data {
my $self = shift;
return ($self->plan);
}
=item C<< graph ( $g ) >>
=cut
sub graph {
my $self = shift;
my $g = shift;
die "graph is unimplemented for sub-selects";
}
1;
__END__
=back
=head1 AUTHOR
Gregory Todd Williams <gwilliams@cpan.org>
=cut
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