/usr/share/perl5/RDF/Query/Algebra/Project.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::Project - Algebra class for projection
=head1 VERSION
This document describes RDF::Query::Algebra::Project version 2.918.
=cut
package RDF::Query::Algebra::Project;
use strict;
use warnings;
no warnings 'redefine';
use base qw(RDF::Query::Algebra);
use Data::Dumper;
use Set::Scalar;
use Scalar::Util qw(reftype blessed refaddr);
use Carp qw(carp croak confess);
use RDF::Trine::Iterator qw(sgrep);
######################################################################
our ($VERSION);
BEGIN {
$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 ( $pattern, \@vars_and_exprs ) >>
Returns a new Project structure.
=cut
sub new {
my $class = shift;
my $pattern = shift;
my $vars = shift;
unless (blessed($pattern)) {
throw RDF::Query::Error::MethodInvocationError -text => "Sub-pattern in RDF::Query::Algebra::Project constructor must be a valid algebra object";
}
unless (reftype($vars) eq 'ARRAY' and not(blessed($vars))) {
throw RDF::Query::Error::MethodInvocationError -text => "Variable list in RDF::Query::Algebra::Project constructor must be an ARRAY reference";
}
my @vars;
foreach my $v (@$vars) {
if ($v->isa('RDF::Query::Node::Variable')) {
push(@vars, $v);
} else {
push(@vars, $v->alias);
}
}
return bless( [ $pattern, \@vars ], $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 $vars = $self->vars;
return ($pattern, $vars);
}
=item C<< pattern >>
Returns the pattern to be sorted.
=cut
sub pattern {
my $self = shift;
if (@_) {
$self->[0] = shift;
}
return $self->[0];
}
=item C<< vars >>
Returns the vars to be projected to.
=cut
sub vars {
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} || ' ';
my $vars = join(' ',
map {
($_->isa('RDF::Query::Node::Variable')) ? '?' . $_->name : $_->sse( $context )
} @{ $self->vars }
);
return sprintf(
"(project (%s)\n${prefix}${indent}%s\n${prefix})",
$vars,
$self->pattern->sse( $context, "${prefix}${indent}" ),
);
}
sub _from_sse {
my $class = shift;
my $context = $_[1];
for ($_[0]) {
if (m/^[(]project\s+[(]\s*/) {
my @nodes;
s/^[(]project\s+[(]\s*//;
do {
push(@nodes, RDF::Trine::Node->from_sse( $_[0], $context ));
} until (m/\s*[)]/);
if (m/^\s*[)]/) {
s/^\s*[)]\s*//;
} else {
throw RDF::Trine::Error -text => "Cannot parse end-of-project-vars from SSE string: >>$_<<";
}
my ($pattern) = RDF::Query::Algebra->from_sse( $context, $_[0] );
if (m/^\s*[)]/) {
s/^\s*[)]\s*//;
warn "project: " . Dumper(\@nodes);
return RDF::Query::Algebra::Project->new( $pattern, \@nodes );
} else {
throw RDF::Trine::Error -text => "Cannot parse end-of-project from SSE string: >>$_<<";
}
} else {
throw RDF::Trine::Error -text => "Cannot parse project from SSE string: >>$_<<";
}
}
}
=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 $pattern = $self->pattern;
$context->{ force_ggp_braces }++;
my ($vars, $_sparql);
my $vlist = $self->vars;
my (@vars);
foreach my $k (@$vlist) {
if ($k->isa('RDF::Query::Expression')) {
push(@vars, $k->sse({}, ''));
} elsif ($k->isa('RDF::Query::Node::Variable')) {
push(@vars, '?' . $k->name);
} else {
push(@vars, $k);
}
}
my $aggregate = 0;
my $group = '';
my $having = '';
my $order = '';
my %agg_projections;
my @aggs = $pattern->subpatterns_of_type( 'RDF::Query::Algebra::Aggregate' );
if (@aggs) {
# aggregate check
my $p = $pattern;
if ($p->isa('RDF::Query::Algebra::Sort')) {
$context->{ skip_sort }++;
$order = $p->_as_sparql_order_exprs( $context, $indent );
$p = $p->pattern
}
if ($p->isa('RDF::Query::Algebra::Filter')) {
$context->{ skip_filter }++;
$having = $p->expr->as_sparql( $context, $indent );
$p = $p->pattern;
}
$p = ($p->patterns)[0] if ($p->isa('RDF::Query::Algebra::GroupGraphPattern') and scalar(@{[$p->patterns]}) == 1);
if ($p->isa('RDF::Query::Algebra::Extend') and $p->pattern->isa('RDF::Query::Algebra::Aggregate')) {
my $pp = $p->pattern;
$context->{ skip_extend }++;
my $vlist = $p->vars;
foreach my $k (@$vlist) {
if ($k->isa('RDF::Query::Expression::Alias')) {
my $var = $k->name;
my $expr = $k->expression;
my $exprstr;
if ($expr->isa('RDF::Query::Expression::Binary')) {
$exprstr = $expr->as_sparql( $context, $indent );
} else {
$exprstr = $k->expression->name;
}
my $str = "($exprstr AS ?$var)";
$agg_projections{ '?' . $var } = $str;
} else {
warn Dumper($k) . ' ';
}
}
my @groups = $pp->groupby;
if (@groups) {
$group = join(' ', map { $_->as_sparql($context, $indent) } @groups);
}
}
}
if ($pattern->isa('RDF::Query::Algebra::Extend')) {
my %seen;
my $vlist = $pattern->vars;
foreach my $k (@$vlist) {
if ($k->isa('RDF::Query::Expression::Alias')) {
$seen{ '?' . $k->name } = $k->as_sparql({}, '');
} elsif ($k->isa('RDF::Query::Expression')) {
push(@vars, $k->as_sparql({}, ''));
} elsif ($k->isa('RDF::Query::Node::Variable')) {
push(@vars, '?' . $k->name);
} else {
push(@vars, $k);
}
}
@vars = map { exists($seen{$_}) ? $seen{$_} : $_ } @vars;
$vars = join(' ', @vars);
my $pp = $pattern->pattern;
if ($pp->isa('RDF::Query::Algebra::Aggregate')) {
$_sparql = $pp->pattern->as_sparql( $context, $indent );
my @groups = $pp->groupby;
if (@groups) {
$group = join(' ', map { $_->as_sparql($context, $indent) } @groups);
}
} else {
$_sparql = $pp->as_sparql( $context, $indent );
}
} else {
my $pvars = join(' ', map { my $agg = $agg_projections{ "?$_" }; defined($agg) ? $agg : "?$_" } sort $self->pattern->referenced_variables);
my $svars = join(' ', map { my $agg = $agg_projections{ $_ }; defined($agg) ? $agg : $_ } sort @vars);
$vars = ($pvars eq $svars) ? '*' : join(' ', map { my $agg = $agg_projections{ $_ }; defined($agg) ? $agg : $_ } @vars);
$_sparql = $pattern->as_sparql( $context, $indent );
}
my $sparql = sprintf("%s WHERE %s", $vars, $_sparql);
if ($group) {
$sparql .= "\n${indent}GROUP BY $group";
}
if ($having) {
$sparql .= "\n${indent}HAVING $having";
}
if ($order) {
$sparql .= "\n${indent}ORDER BY $order";
}
return $sparql;
}
=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),
variables => [ map { $_->as_hash } @{ $self->vars } ],
pattern => $self->pattern->as_hash,
};
}
=item C<< as_spin ( $model ) >>
Adds statements to the given model to represent this algebra object in the
SPARQL Inferencing Notation (L<http://www.spinrdf.org/>).
=cut
sub as_spin {
my $self = shift;
my $model = shift;
my $spin = RDF::Trine::Namespace->new('http://spinrdf.org/spin#');
my $rdf = RDF::Trine::Namespace->new('http://www.w3.org/1999/02/22-rdf-syntax-ns#');
my $q = RDF::Query::Node::Blank->new();
my @nodes = $self->pattern->as_spin( $model );
$model->add_statement( RDF::Trine::Statement->new($q, $rdf->type, $spin->Select) );
my @vars = map { RDF::Query::Node::Blank->new( "variable_" . $_->name ) } @{ $self->vars };
my $vlist = $model->add_list( @vars );
$model->add_statement( RDF::Trine::Statement->new($q, $spin->resultVariables, $vlist) );
my $list = $model->add_list( @nodes );
$model->add_statement( RDF::Trine::Statement->new($q, $spin->where, $list) );
return $q;
}
=item C<< type >>
Returns the type of this algebra expression.
=cut
sub type {
return 'PROJECT';
}
=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 = $self->pattern->referenced_variables;
foreach my $v (@{ $self->vars }) {
if ($v->isa('RDF::Query::Node::Variable')) {
push(@vars, $v->name);
} else {
push(@vars, $v->referenced_variables);
}
}
return RDF::Query::_uniq(@vars);
}
=item C<< bind_variables ( \%bound ) >>
Returns a new algebra pattern with variables named in %bound replaced by their corresponding bound values.
=cut
sub bind_variables {
my $self = shift;
my $class = ref($self);
my $bound = shift;
my $pattern = $self->pattern->bind_variables( $bound );
my $vars = $self->vars;
my @vars;
foreach my $v (@$vars) {
if (blessed($v) and $v->isa('RDF::Query::Node::Variable') and exists $bound->{ $v->name }) {
push(@vars, $bound->{ $v->name });
} else {
push(@vars, $v);
}
}
return $class->new( $pattern, \@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;
# push(@vars, $self->pattern->potentially_bound);
foreach my $v (@{ $self->vars }) {
if ($v->isa('RDF::Query::Node::Variable')) {
push(@vars, $v->name);
} else {
push(@vars, $v->potentially_bound);
}
}
return RDF::Query::_uniq(@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->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
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