/usr/share/perl5/RDF/Query/Algebra/Extend.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::Algebra::Extend - Algebra class for extending the variable projection
=head1 VERSION
This document describes RDF::Query::Algebra::Extend version 2.918.
=cut
package RDF::Query::Algebra::Extend;
use strict;
use warnings;
no warnings 'redefine';
use base qw(RDF::Query::Algebra);
use Data::Dumper;
use Set::Scalar;
use Scalar::Util qw(reftype blessed);
use Carp qw(carp croak confess);
use RDF::Trine::Iterator qw(sgrep);
######################################################################
our ($VERSION);
BEGIN {
$VERSION = '2.918';
}
######################################################################
=head1 METHODS
Beyond the methods documented below, this class inherits methods from the
L<RDF::Query::Algebra> class.
=over 4
=cut
=item C<< new ( $pattern, \@vars_and_exprs ) >>
Returns a new Extend structure.
=cut
sub new {
my $class = shift;
my $pattern = shift;
my $vars = shift;
unless (reftype($vars) eq 'ARRAY' and not(blessed($vars))) {
throw RDF::Query::Error::MethodInvocationError -text => "Variable list in RDF::Query::Algebra::Extend constructor must be an ARRAY reference";
}
my @vars = grep { $_->isa('RDF::Query::Expression::Alias') } @$vars;
return bless( [ $pattern, \@vars ], $class );
}
=item C<< construct_args >>
Returns a list of arguments that, passed to this class' constructor,
will produce a clone of this algebra pattern.
=cut
sub construct_args {
my $self = shift;
my $pattern = $self->pattern;
my $vars = $self->vars;
return ($pattern, $vars);
}
=item C<< pattern >>
Returns the pattern to be sorted.
=cut
sub pattern {
my $self = shift;
if (@_) {
$self->[0] = shift;
}
return $self->[0];
}
=item C<< vars >>
Returns the vars to be extended.
=cut
sub vars {
my $self = shift;
return $self->[1];
}
=item C<< sse >>
Returns the SSE string for this algebra expression.
=cut
sub sse {
my $self = shift;
my $context = shift;
my $prefix = shift || '';
my $indent = $context->{indent} || ' ';
my $vars = join(' ',
map {
($_->isa('RDF::Query::Node::Variable')) ? '?' . $_->name : $_->sse( $context )
} @{ $self->vars }
);
return sprintf(
"(extend (%s)\n${prefix}${indent}%s\n${prefix})",
$vars,
$self->pattern->sse( $context, "${prefix}${indent}" ),
);
}
sub _from_sse {
my $class = shift;
my $context = $_[1];
for ($_[0]) {
if (m/^[(]extend\s+[(]\s*/) {
my @nodes;
s/^[(]extend\s+[(]\s*//;
do {
push(@nodes, RDF::Trine::Node->from_sse( $_[0], $context ));
} until (m/\s*[)]/);
if (m/^\s*[)]/) {
s/^\s*[)]\s*//;
} else {
throw RDF::Trine::Error -text => "Cannot parse end-of-extend-vars from SSE string: >>$_<<";
}
my ($pattern) = RDF::Query::Algebra->from_sse( $context, $_[0] );
if (m/^\s*[)]/) {
s/^\s*[)]\s*//;
return RDF::Query::Algebra::Extend->new( $pattern, \@nodes );
} else {
throw RDF::Trine::Error -text => "Cannot parse end-of-extend from SSE string: >>$_<<";
}
} else {
throw RDF::Trine::Error -text => "Cannot parse extend from SSE string: >>$_<<";
}
}
}
=item C<< as_sparql >>
Returns the SPARQL string for this algebra expression.
=cut
sub as_sparql {
my $self = shift;
my $context = shift || {};
my $indent = shift;
if ($context->{ skip_extend }) {
$context->{ skip_extend }--;
return $self->pattern->as_sparql( $context, $indent );
}
my $pattern = $self->pattern;
my $vlist = $self->vars;
my (@vars);
foreach my $k (@$vlist) {
if ($k->isa('RDF::Query::Expression')) {
push(@vars, $k->as_sparql({}, ''));
} elsif ($k->isa('RDF::Query::Node::Variable')) {
push(@vars, '?' . $k->name);
} else {
push(@vars, $k);
}
}
my $ggp = $pattern->as_sparql( $context, $indent );
my $sparql = $ggp;
foreach my $v (@vars) {
$sparql .= "\n${indent}BIND" . $v;
}
return $sparql;
}
=item C<< as_hash >>
Returns the query as a nested set of plain data structures (no objects).
=cut
sub as_hash {
my $self = shift;
my $context = shift;
return {
type => lc($self->type),
pattern => $self->pattern->as_hash,
vars => [ map { $_->as_hash } @{ $self->vars } ],
};
}
=item C<< type >>
Returns the type of this algebra expression.
=cut
sub type {
return 'PROJECT';
}
=item C<< referenced_variables >>
Returns a list of the variable names used in this algebra expression.
=cut
sub referenced_variables {
my $self = shift;
my @vars = $self->pattern->referenced_variables;
foreach my $v (@{ $self->vars }) {
if ($v->isa('RDF::Query::Node::Variable')) {
push(@vars, $v->name);
} else {
push(@vars, $v->referenced_variables);
}
}
return RDF::Query::_uniq(@vars);
}
=item C<< potentially_bound >>
Returns a list of the variable names used in this algebra expression that will
bind values during execution.
=cut
sub potentially_bound {
my $self = shift;
my @vars;
push(@vars, $self->pattern->potentially_bound);
foreach my $v (@{ $self->vars }) {
if ($v->isa('RDF::Query::Node::Variable')) {
push(@vars, $v->name);
} else {
push(@vars, $v->potentially_bound);
}
}
return RDF::Query::_uniq(@vars);
}
=item C<< definite_variables >>
Returns a list of the variable names that will be bound after evaluating this algebra expression.
=cut
sub definite_variables {
my $self = shift;
return $self->pattern->definite_variables;
}
=item C<< is_solution_modifier >>
Returns true if this node is a solution modifier.
=cut
sub is_solution_modifier {
return 1;
}
1;
__END__
=back
=head1 AUTHOR
Gregory Todd Williams <gwilliams@cpan.org>
=cut
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