/usr/share/perl5/RDF/Query/Plan/Construct.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::Construct - Executable query plan for constructing a graph from a set of variable bindings.
=head1 VERSION
This document describes RDF::Query::Plan::Construct 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::Construct;
use strict;
use warnings;
use base qw(RDF::Query::Plan);
use Log::Log4perl;
use Scalar::Util qw(blessed refaddr);
######################################################################
our ($VERSION);
BEGIN {
$VERSION = '2.918';
}
######################################################################
=item C<< new ( $plan, \@triples ) >>
=cut
sub new {
my $class = shift;
my $plan = shift;
my $triples = shift;
unless (@$triples) {
throw RDF::Query::Error::MethodInvocationError -text => "No triples passed to ::Plan::Construct constructor";
}
my $self = $class->SUPER::new( $plan, $triples );
$self->[0]{referenced_variables} = [ $plan->referenced_variables ];
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 => "CONSTRUCT plan can't be executed while already open";
}
my $l = Log::Log4perl->get_logger("rdf.query.plan.construct");
$l->trace( "executing RDF::Query::Plan::Construct" );
my $plan = $self->pattern;
$plan->execute( $context );
if ($plan->state == $self->OPEN) {
$self->[0]{triples} = [];
$self->[0]{blank_map} = {};
$self->state( $self->OPEN );
} else {
warn "could not execute plan in construct";
}
$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 CONSTRUCT";
}
my $l = Log::Log4perl->get_logger("rdf.query.plan.triple");
my $plan = $self->[1];
while (1) {
while (scalar(@{ $self->[0]{triples} })) {
my $t = shift(@{ $self->[0]{triples} });
if (my $d = $self->delegate) {
$d->log_result( $self, $t );
}
return $t;
}
my $row = $plan->next;
return undef unless ($row);
$self->[0]{blank_map} = {};
if ($l->is_debug) {
$l->debug( "- got construct bindings from pattern: " . $row->as_string );
}
my $triples = $self->triples;
foreach my $t (@$triples) {
if ($l->is_debug) {
$l->debug( "- filling-in construct triple pattern: " . $t->as_string );
}
my @triple = $t->nodes;
for my $i (0 .. 2) {
if ($triple[$i]->isa('RDF::Trine::Node::Variable')) {
my $name = $triple[$i]->name;
$triple[$i] = $row->{ $name };
} elsif ($triple[$i]->isa('RDF::Trine::Node::Blank')) {
my $id = $triple[$i]->blank_identifier;
unless (exists($self->[0]{blank_map}{ $id })) {
$self->[0]{blank_map}{ $id } = RDF::Trine::Node::Blank->new();
}
$triple[$i] = $self->[0]{blank_map}{ $id };
}
}
my $ok = 1;
foreach (@triple) {
if (not blessed($_)) {
$ok = 0;
}
}
next unless ($ok);
my $st = RDF::Trine::Statement->new( @triple );
unless ($self->[0]{seen}{ $st->as_string }++) {
push(@{ $self->[0]{triples} }, $st);
}
}
}
}
=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 CONSTRUCT";
}
delete $self->[0]{blank_map};
delete $self->[0]{triples};
if ($self->[1] and $self->[1]->state == $self->OPEN) {
$self->[1]->close();
}
$self->SUPER::close();
}
=item C<< pattern >>
Returns the query plan that will be used to produce the variable bindings for constructing the new graph.
=cut
sub pattern {
my $self = shift;
return $self->[1];
}
=item C<< triples >>
Returns the triples that are to be used in constructing the new graph for each variable binding.
=cut
sub triples {
my $self = shift;
return $self->[2];
}
=item C<< distinct >>
Returns true if the pattern is guaranteed to return distinct results.
=cut
sub distinct {
return 0;
}
=item C<< ordered >>
Returns true if the pattern is guaranteed to return ordered results.
=cut
sub ordered {
my $self = shift;
return [];
}
=item C<< plan_node_name >>
Returns the string name of this plan node, suitable for use in serialization.
=cut
sub plan_node_name {
return 'construct';
}
=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 \T);
}
=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->pattern, [ @{ $self->triples } ]);
}
=item C<< explain >>
Returns a string serialization of the query plan appropriate for display
on the command line.
=cut
sub explain {
my $self = shift;
my ($s, $count) = (' ', 0);
if (@_) {
$s = shift;
$count = shift;
}
my $indent = '' . ($s x $count);
my $type = $self->plan_node_name;
my $string = sprintf("%s%s (0x%x)\n", $indent, $type, refaddr($self));
$string .= $self->pattern->explain( $s, $count+1 );
$string .= "${indent}${s}pattern\n";
foreach my $t (@{ $self->triples }) {
$string .= "${indent}${s}${s}" . $t->as_sparql . "\n";
}
return $string;
}
=item C<< graph ( $g ) >>
=cut
sub graph {
my $self = shift;
my $g = shift;
my $c = $self->pattern->graph( $g );
$g->add_node( "$self", label => "Construct" . $self->graph_labels );
$g->add_edge( "$self", $c );
return "$self";
}
=item C<< as_iterator ( $context ) >>
Returns an RDF::Trine::Iterator object for the current (already executed) plan.
=cut
sub as_iterator {
my $self = shift;
my $context = shift;
my $stream = RDF::Trine::Iterator::Graph->new( sub { $self->next } );
return $stream;
}
1;
__END__
=back
=head1 AUTHOR
Gregory Todd Williams <gwilliams@cpan.org>
=cut
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