RDF::Query::Algebra::Distinct - Algebra class for distinct query results
Index
Code Index:
NAME
RDF::Query::Algebra::Distinct - Algebra class for distinct query results
VERSION
This document describes RDF::Query::Algebra::Distinct version 2.907.
METHODS
Beyond the methods documented below, this class inherits methods from the
RDF::Query::Algebra class.
new ( $pattern )-
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.
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).
as_spin ( $model )-
Adds statements to the given model to represent this algebra object in the
SPARQL Inferencing Notation (http://www.spinrdf.org/).
type-
Returns the type of this algebra expression.
referenced_variables-
Returns a list of the variable names used in this algebra expression.
potentially_bound-
Returns a list of the variable names used in this algebra expression that will
bind values during execution.
definite_variables-
Returns a list of the variable names that will be bound after evaluating this algebra expression.
is_solution_modifier-
Returns true if this node is a solution modifier.
AUTHOR
Gregory Todd Williams <gwilliams@cpan.org>
# RDF::Query::Algebra::Distinct
# -----------------------------------------------------------------------------
package RDF::Query::Algebra::Distinct;
use strict;
use warnings;
no warnings 'redefine';
use base qw(RDF::Query::Algebra);
use Data::Dumper;
use Set::Scalar;
use Scalar::Util qw(blessed);
use Carp qw(carp croak confess);
use RDF::Trine::Iterator qw(sgrep);
######################################################################
our ($VERSION);
BEGIN {
$VERSION = '2.907';
}
######################################################################
sub new {
my $class = shift;
my $pattern = shift;
return bless( [ $pattern ], $class );
}
sub construct_args {
my $self = shift;
my $pattern = $self->pattern;
return ($pattern);
}
sub pattern {
my $self = shift;
if (@_) {
$self->[0] = shift;
}
return $self->[0];
}
sub sse {
my $self = shift;
my $context = shift;
my $prefix = shift || '';
my $indent = $context->{indent} || ' ';
return sprintf(
"(distinct\n${prefix}${indent}%s)",
$self->pattern->sse( $context, "${prefix}${indent}" ),
);
}
sub as_sparql {
my $self = shift;
my $context = shift;
my $indent = shift;
return 'DISTINCT ' . $self->pattern->as_sparql( $context, $indent );
}
sub as_hash {
my $self = shift;
my $context = shift;
return {
type => lc($self->type),
pattern => $self->pattern->as_hash,
};
}
sub as_spin {
my $self = shift;
my $model = shift;
my $spin = RDF::Trine::Namespace->new('http://spinrdf.org/spin#');
my $xsd = RDF::Trine::Namespace->new('http://www.w3.org/2001/XMLSchema#');
my $q = $self->pattern->as_spin( $model );
$model->add_statement( RDF::Trine::Statement->new($q, $spin->distinct, RDF::Query::Node::Literal->new('true', undef, $xsd->boolean)) );
return $q;
}
sub type {
return 'DISTINCT';
}
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__