RDF::Query::Algebra::Construct - Algebra class for construct query results
Index
Code Index:
NAME
RDF::Query::Algebra::Construct - Algebra class for construct query results
VERSION
This document describes RDF::Query::Algebra::Construct version 2.907.
METHODS
Beyond the methods documented below, this class inherits methods from the
RDF::Query::Algebra class.
new ( $query_pattern, \@construct_triples )-
Returns a new Sort structure.
construct_args-
Returns a list of arguments that, passed to this class' constructor,
will produce a clone of this algebra pattern.
pattern-
Returns the pattern used to produce the variable bindings used in graph construction.
triples-
Returns an ARRAY ref of triples to be used in graph construction.
sse-
Returns the SSE string for this algebra expression.
as_sparql-
Returns the SPARQL string for this algebra expression.
as_hash-
Returns the query as a nested set of plain data structures (no objects).
type-
Returns the type of this algebra expression.
referenced_variables-
Returns a list of the variable names used in this algebra expression.
potentially_bound-
Returns a list of the variable names used in this algebra expression that will
bind values during execution.
definite_variables-
Returns a list of the variable names that will be bound after evaluating this algebra expression.
AUTHOR
Gregory Todd Williams <gwilliams@cpan.org>
# RDF::Query::Algebra::Construct
# -----------------------------------------------------------------------------
package RDF::Query::Algebra::Construct;
use strict;
use warnings;
no warnings 'redefine';
use base qw(RDF::Query::Algebra);
use Data::Dumper;
use Set::Scalar;
use Scalar::Util qw(blessed);
use Carp qw(carp croak confess);
use RDF::Trine::Iterator qw(sgrep);
######################################################################
our ($VERSION);
BEGIN {
$VERSION = '2.907';
}
######################################################################
sub new {
my $class = shift;
my $pattern = shift;
my $triples = shift;
return bless( [ $pattern, $triples ], $class );
}
sub construct_args {
my $self = shift;
my $pattern = $self->pattern;
my $triples = $self->triples;
return ($pattern, $triples);
}
sub pattern {
my $self = shift;
if (@_) {
$self->[0] = shift;
}
return $self->[0];
}
sub triples {
my $self = shift;
if (@_) {
$self->[1] = shift;
}
return $self->[1];
}
sub sse {
my $self = shift;
my $context = shift;
my $prefix = shift || '';
my $indent = $context->{indent} || ' ';
my $triples = join("\n${prefix}${indent}${indent}", map { $_->sse( $context, "${prefix}${indent}${indent}" ) } @{$self->triples});
return sprintf(
"(construct\n${prefix}${indent}(\n${prefix}${indent}${indent}%s\n${prefix}${indent})\n${prefix}${indent}%s)",
$triples,
$self->pattern->sse( $context, "${prefix}${indent}" ),
);
}
sub as_sparql {
my $self = shift;
my $context = shift || {};
my $indent = shift;
my $triples = $self->triples;
my $bgp = RDF::Query::Algebra::BasicGraphPattern->new( @$triples );
my $ggp = RDF::Query::Algebra::GroupGraphPattern->new( $bgp );
my $force = $context->{ force_ggp_braces } || 0;
my ($template, $pattern);
{
$context->{ force_ggp_braces } = $force + 1;
$template = $ggp->as_sparql( $context, $indent );
}
{
$context->{ force_ggp_braces } = $force + 1;
$pattern = $self->pattern->as_sparql( $context, $indent );
}
my $string = sprintf(
"CONSTRUCT %s\n${indent}WHERE %s",
$template,
$pattern,
);
return $string;
}
sub as_hash {
my $self = shift;
my $context = shift;
my $bgp = RDF::Query::Algebra::BasicGraphPattern->new( @{ $self->triples } );
return {
type => lc($self->type),
pattern => $self->pattern->as_hash,
construct => $bgp->as_hash,
};
}
sub type {
return 'CONSTRUCT';
}
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;
}
1;
__END__