RDF::Query::Algebra::Offset - Algebra class for offseting query results

RDF-Query documentation Contained in the RDF-Query distribution.

Index

Code Index:

NAME

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RDF::Query::Algebra::Offset - Algebra class for offseting query results

VERSION

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This document describes RDF::Query::Algebra::Offset version 2.907.

METHODS

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Beyond the methods documented below, this class inherits methods from the RDF::Query::Algebra class.

new ( $pattern, $offset )

Returns a new Sort structure.

construct_args

Returns a list of arguments that, passed to this class' constructor, will produce a clone of this algebra pattern.

pattern

Returns the pattern to be sorted.

offset

Returns the offset number of the pattern.

sse

Returns the SSE string for this algebra expression.

as_sparql

Returns the SPARQL string for this algebra expression.

as_hash

Returns the query as a nested set of plain data structures (no objects).

type

Returns the type of this algebra expression.

referenced_variables

Returns a list of the variable names used in this algebra expression.

potentially_bound

Returns a list of the variable names used in this algebra expression that will bind values during execution.

definite_variables

Returns a list of the variable names that will be bound after evaluating this algebra expression.

is_solution_modifier

Returns true if this node is a solution modifier.

AUTHOR

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 Gregory Todd Williams <gwilliams@cpan.org>
RDF-Query documentation Contained in the RDF-Query distribution. 
# RDF::Query::Algebra::Offset
# -----------------------------------------------------------------------------


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	= '2.907';
}

######################################################################


sub new {
	my $class	= shift;
	my $pattern	= shift;
	my $offset	= shift;
	return bless( [ $pattern, $offset ], $class );
}


sub construct_args {
	my $self	= shift;
	my $pattern	= $self->pattern;
	my $offset	= $self->offset;
	return ($pattern, $offset);
}


sub pattern {
	my $self	= shift;
	if (@_) {
		$self->[0]	= shift;
	}
	return $self->[0];
}


sub offset {
	my $self	= shift;
	return $self->[1];
}


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}" ),
	);
}


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;
}


sub as_hash {
	my $self	= shift;
	my $context	= shift;
	return {
		type 		=> lc($self->type),
		pattern		=> $self->pattern->as_hash,
		offset		=> $self->offset,
	};
}


sub type {
	return 'LIMIT';
}


sub referenced_variables {
	my $self	= shift;
	return RDF::Query::_uniq($self->pattern->referenced_variables);
}


sub potentially_bound {
	my $self	= shift;
	return $self->pattern->potentially_bound;
}


sub definite_variables {
	my $self	= shift;
	return $self->pattern->definite_variables;
}


sub is_solution_modifier {
	return 1;
}



1;

__END__