/usr/share/perl5/RDF/Query/Algebra/Path.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::Path - Algebra class for path patterns
=head1 VERSION
This document describes RDF::Query::Algebra::Path version 2.918.
=cut
package RDF::Query::Algebra::Path;
use strict;
use warnings;
no warnings 'redefine';
use base qw(RDF::Query::Algebra);
use Set::Scalar;
use Scalar::Util qw(blessed);
use Carp qw(carp croak confess);
######################################################################
our ($VERSION, $debug, $lang, $languri);
BEGIN {
$debug = 0;
$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 ( $start, [ $op, @paths ], $end, $graph )>
Returns a new Path structure.
=cut
sub new {
my $class = shift;
my $start = shift;
my $path = shift;
my $end = shift;
my $graph = shift;
return bless( [ $start, $path, $end, $graph ], $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 $self = shift;
return ($self->start, $self->path, $self->end, $self->graph);
}
=item C<< path >>
Returns the path description for this path expression.
=cut
sub path {
my $self = shift;
return $self->[1];
}
=item C<< start >>
Returns the path origin node.
=cut
sub start {
my $self = shift;
return $self->[0];
}
=item C<< end >>
Returns the path destination node.
=cut
sub end {
my $self = shift;
return $self->[2];
}
=item C<< graph >>
Returns the named graph.
=cut
sub graph {
my $self = shift;
return $self->[3];
}
=item C<< distinguish_bnode_variables >>
Returns a new Path object with blank nodes replaced by distinguished variables.
=cut
sub distinguish_bnode_variables {
my $self = shift;
my $class = ref($self);
my @nodes = ($self->start, $self->end);
foreach my $i (0 .. $#nodes) {
if ($nodes[$i]->isa('RDF::Query::Node::Blank')) {
$nodes[$i] = $nodes[$i]->make_distinguished_variable;
}
}
return $class->new( $nodes[0], $self->path, $nodes[1] );
}
=item C<< bounded_length >>
Returns true if the path is of bounded length.
=cut
sub bounded_length {
my $self = shift;
return $self->_bounded_length( $self->path );
}
sub _bounded_length {
my $self = shift;
my $array = shift;
return 1 if blessed($array);
my ($op, @nodes) = @$array;
return 1 if ($op eq '?');
return 0 if ($op =~ /^[*+]$/);
return 1 if ($op =~ /^\d+(-\d+)?$/);
return 0 if ($op =~ /^\d+-$/);
if ($op =~ m<^[/|^]$>) {
my @fixed = map { $self->_bounded_length($_) } @nodes;
foreach my $f (@fixed) {
return 0 unless ($f);
}
return 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 $start = $self->start->sse( $context, $prefix );
my $end = $self->end->sse( $context, $prefix );
my $path = $self->path;
my $psse = $self->_expand_path( $path, 'sse' );
if ($self->graph) {
my $graph = $self->graph->sse( $context, $prefix );
return sprintf( '(path %s %s %s %s)', $start, $psse, $end, $graph );
} else {
return sprintf( '(path %s %s %s)', $start, $psse, $end );
}
}
=item C<< as_sparql >>
Returns the SPARQL string for this algebra expression.
=cut
sub as_sparql {
my $self = shift;
my $context = shift;
my $prefix = shift || '';
my $indent = $context->{indent};
my $start = $self->start->as_sparql( $context, $prefix );
my $end = $self->end->as_sparql( $context, $prefix );
my $path = $self->path;
my $psse = $self->_expand_path( $path, 'as_sparql' );
return sprintf( '%s %s %s .', $start, $psse, $end );
}
sub _expand_path {
my $self = shift;
my $array = shift;
my $method = shift;
if (blessed($array)) {
my $string = $array->$method({}, '');
if ($string eq '<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>') {
return 'a';
} else {
return $string;
}
} else {
my ($op, @nodes) = @$array;
my @nodessse = map { $self->_expand_path($_, $method) } @nodes;
my $psse;
# if ($op eq 'DISTINCT') {
# $psse = 'DISTINCT(' . join('/', @nodessse) . ')';
# }
if ($op eq '+') {
$psse = (scalar(@nodessse) == 1) ? $nodessse[0] . $op : '(' . join('/', @nodessse) . ')' . $op;
} elsif ($op eq '*') {
$psse = (scalar(@nodessse) == 1) ? $nodessse[0] . $op : '(' . join('/', @nodessse) . ')' . $op;
} elsif ($op eq '?') {
$psse = (scalar(@nodessse) == 1) ? $nodessse[0] . $op : '(' . join('/', @nodessse) . ')' . $op;
} elsif ($op eq '!') {
$psse = (scalar(@nodessse) == 1) ? '!' . $nodessse[0] : '!(' . join('|', @nodessse) . ')';
} elsif ($op eq '^') {
$psse = (scalar(@nodessse) == 1) ? $op . $nodessse[0] : '(' . join('/', map { "${op}$_" } @nodessse) . ')';
} elsif ($op eq '/') {
$psse = (scalar(@nodessse) == 1) ? $nodessse[0] : '(' . join('/', @nodessse) . ')';
} elsif ($op eq '|') {
$psse = (scalar(@nodessse) == 1) ? $nodessse[0] : '(' . join('|', @nodessse) . ')';
} elsif ($op =~ /^(\d+)$/) {
$psse = join('/', @nodessse) . '{' . $op . '}';
} elsif ($op =~ /^(\d+)-(\d+)$/) {
$psse = join('/', @nodessse) . "{$1,$2}";
} elsif ($op =~ /^(\d+)-$/) {
$psse = join('/', @nodessse) . "{$1,}";
} else {
confess "Serialization of unknown path type $op";
}
return $psse;
}
}
=item C<< type >>
Returns the type of this algebra expression.
=cut
sub type {
return 'PATH';
}
=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 = grep { $_->isa('RDF::Query::Node::Variable') } ($self->start, $self->end);
return RDF::Query::_uniq(map { $_->name } @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 = grep { $_->isa('RDF::Query::Node::Variable') } ($self->start, $self->end);
return RDF::Query::_uniq(map { $_->name } @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->referenced_variables;
}
1;
__END__
=back
=head1 AUTHOR
Gregory Todd Williams <gwilliams@cpan.org>
=cut
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