# RDF::Query::Algebra::Offset
# -----------------------------------------------------------------------------
=head1 NAME
RDF::Query::Algebra::Offset - Algebra class for offseting query results
=head1 VERSION
This document describes RDF::Query::Algebra::Offset version 2.915.
=cut
package RDF::Query::Algebra::Offset;
use strict;
use warnings;
no warnings 'redefine';
use base qw(RDF::Query::Algebra);
use Data::Dumper;
use Set::Scalar;
use Scalar::Util qw(blessed);
use Carp qw(carp croak confess);
use RDF::Trine::Iterator qw(sgrep);
######################################################################
our ($VERSION);
BEGIN {
$VERSION = '2.915';
}
######################################################################
=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, $offset ) >>
Returns a new Sort structure.
=cut
sub new {
my $class = shift;
my $pattern = shift;
my $offset = shift;
return bless( [ $pattern, $offset ], $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 $offset = $self->offset;
return ($pattern, $offset);
}
=item C<< pattern >>
Returns the pattern to be sorted.
=cut
sub pattern {
my $self = shift;
if (@_) {
$self->[0] = shift;
}
return $self->[0];
}
=item C<< offset >>
Returns the offset number of the pattern.
=cut
sub offset {
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 = $context->{indent};
return sprintf(
"(offset %s\n${prefix}${indent}%s)",
$self->offset,
$self->pattern->sse( $context, "${prefix}${indent}" ),
);
}
=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;
my $string = sprintf(
"%s\nOFFSET %d",
$self->pattern->as_sparql( $context, $indent ),
$self->offset,
);
return $string;
}
=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,
offset => $self->offset,
};
}
=item C<< type >>
Returns the type of this algebra expression.
=cut
sub type {
return 'LIMIT';
}
=item C<< referenced_variables >>
Returns a list of the variable names used in this algebra expression.
=cut
sub referenced_variables {
my $self = shift;
return RDF::Query::_uniq($self->pattern->referenced_variables);
}
=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;
return $self->pattern->potentially_bound;
}
=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