use v5.14;
use warnings;
=head1 NAME
Attean::SimpleQueryEvaluator - Simple query evaluator
=head1 VERSION
This document describes Attean::SimpleQueryEvaluator version 0.030
=head1 SYNOPSIS
use v5.14;
use Attean;
my $algebra = Attean->get_parser('SPARQL')->parse('SELECT * WHERE { ... }');
my $active_graph = Attean::IRI->new('http://example.org/');
my $e = Attean::SimpleQueryEvaluator->new( model => $model );
my $iter = $e->evaluate( $algebra, $active_graph );
=head1 DESCRIPTION
The Attean::SimpleQueryEvaluator class implements a simple query evaluator that,
given an L<Attean::API::Algebra|Attean::API::Query> and a L<Attean::API::Model>
object, evaluates the query represented by the algebra using data from the
model, and returns a query result.
=head1 ATTRIBUTES
=over 4
=cut
use Attean::Algebra;
use Attean::Expression;
package Attean::SimpleQueryEvaluator 0.030 {
use Moo;
use Encode qw(encode);
use Attean::RDF;
use LWP::UserAgent;
use Scalar::Util qw(blessed);
use List::Util qw(all any reduce);
use Types::Standard qw(ConsumerOf InstanceOf Bool);
use URI::Escape;
use namespace::clean;
=item C<< model >>
The L<Attean::API::Model> object used for query evaluation.
=cut
has 'model' => (is => 'ro', isa => ConsumerOf['Attean::API::Model'], required => 1);
=item C<< default_graph >>
The L<Attean::API::IRI> object representing the default graph in the C<< model >>.
The default graph will be excluded from enumeration of graph names for query
features such as C<< GRAPH ?g {} >>.
=cut
has 'default_graph' => (is => 'ro', isa => ConsumerOf['Attean::API::IRI'], required => 1);
has 'user_agent' => (is => 'rw', isa => InstanceOf['LWP::UserAgent'], default => sub { my $ua = LWP::UserAgent->new(); $ua->agent("Attean/$Attean::VERSION " . $ua->_agent); $ua });
has 'ground_blanks' => (is => 'rw', isa => Bool, default => 0);
=back
=head1 METHODS
=over 4
=item C<< evaluate( $algebra, $active_graph ) >>
Returns an L<Attean::API::Iterator> object with results produced by evaluating
the query C<< $algebra >> against the evaluator's C<< model >>, using the
supplied C<< $active_graph >>.
=cut
sub evaluate {
my $self = shift;
my $algebra = shift;
my $active_graph = shift || Carp::confess "No active-graph passed to Attean::SimpleQueryEvaluator->evaluate";
Carp::confess "No algebra passed for evaluation" unless ($algebra);
my $expr_eval = Attean::SimpleQueryEvaluator::ExpressionEvaluator->new( evaluator => $self );
my @children = @{ $algebra->children };
my ($child) = $children[0];
if ($algebra->isa('Attean::Algebra::Query') or $algebra->isa('Attean::Algebra::Update')) {
return $self->evaluate($algebra->child, $active_graph, @_);
} elsif ($algebra->isa('Attean::Algebra::BGP')) {
my @triples = @{ $algebra->triples };
if (scalar(@triples) == 0) {
my $b = Attean::Result->new( bindings => {} );
return Attean::ListIterator->new(variables => [], values => [$b], item_type => 'Attean::API::Result');
} else {
my @iters;
my @new_vars;
my %blanks;
foreach my $t (@triples) {
my $q = $t->as_quad_pattern($active_graph);
my @values;
foreach my $v ($q->values) {
if (not($self->ground_blanks) and $v->does('Attean::API::Blank')) {
unless (exists $blanks{$v->value}) {
$blanks{$v->value} = Attean::Variable->new();
push(@new_vars, $blanks{$v->value}->value);
}
push(@values, $blanks{$v->value});
} else {
push(@values, $v);
}
}
push(@iters, $self->model->get_bindings( @values ));
}
while (scalar(@iters) > 1) {
my ($lhs, $rhs) = splice(@iters, 0, 2);
unshift(@iters, $lhs->join($rhs));
}
return shift(@iters)->map(sub { shift->project_complement(@new_vars) });
}
} elsif ($algebra->isa('Attean::Algebra::Distinct') or $algebra->isa('Attean::Algebra::Reduced')) {
my %seen;
my $iter = $self->evaluate( $child, $active_graph );
return $iter->grep(sub { return not($seen{ shift->as_string }++); });
} elsif ($algebra->isa('Attean::Algebra::Extend')) {
my $child = $algebra;
my @extends;
my %extends;
while ($child->isa('Attean::Algebra::Extend')) {
my $expr = $child->expression;
my $var = $child->variable->value;
$extends{ $var } = $expr;
unshift(@extends, $var);
($child) = @{ $child->children };
}
return $self->evaluate( $child, $active_graph )->map(sub {
my $r = shift;
my %extension;
my %row_cache;
foreach my $var (@extends) {
my $expr = $extends{ $var };
my $val = $expr_eval->evaluate_expression( $expr, $r, $active_graph, \%row_cache );
# warn "Extend error: $@" if ($@);
$r = Attean::Result->new( bindings => { $var => $val } )->join($r) if ($val);
}
return $r;
});
} elsif ($algebra->isa('Attean::Algebra::Filter')) {
# TODO: Merge adjacent filter evaluation so that they can share a row_cache hash (as is done for Extend above)
my $expr = $algebra->expression;
my $iter = $self->evaluate( $child, $active_graph );
return $iter->grep(sub {
my $t = $expr_eval->evaluate_expression( $expr, shift, $active_graph, {} );
# if ($@) { warn "Filter evaluation: $@\n" };
return ($t ? $t->ebv : 0);
});
} elsif ($algebra->isa('Attean::Algebra::OrderBy')) {
my $iter = $self->evaluate( $child, $active_graph );
my @rows = $iter->elements;
my @cmps = @{ $algebra->comparators };
my @exprs = map { $_->expression } @cmps;
my @dirs = map { $_->ascending } @cmps;
my @sorted = map { $_->[0] } sort {
my ($ar, $avalues) = @$a;
my ($br, $bvalues) = @$b;
my $c = 0;
foreach my $i (0 .. $#cmps) {
my ($av, $bv) = map { $_->[$i] } ($avalues, $bvalues);
$c = $av ? $av->compare($bv) : 1;
$c *= -1 if ($dirs[$i] == 0);
last unless ($c == 0);
}
$c
} map { my $r = $_; [$r, [map { $expr_eval->evaluate_expression( $_, $r, $active_graph, {} ) } @exprs]] } @rows;
return Attean::ListIterator->new( values => \@sorted, item_type => $iter->item_type, variables => $iter->variables);
} elsif ($algebra->isa('Attean::Algebra::Service')) {
my $endpoint = $algebra->endpoint->value;
my ($pattern) = @{ $algebra->children };
my $sparql = Attean::Algebra::Project->new( variables => [ map { variable($_) } $pattern->in_scope_variables ], children => [ $pattern ] )->as_sparql;
my $url = $endpoint . '?query=' . uri_escape($sparql); # TODO: fix for cases where $endpoint already contains query parameters
my $ua = $self->user_agent;
my $req = HTTP::Request->new('GET', $url );
my $response = $ua->request($req);
if (blessed($response) and $response->is_success) {
my $type = $response->header('Content-Type');
my $pclass = Attean->get_parser(media_type => $type) or die "No parser for media type: $type";
my $parser = $pclass->new();
my $xml = $response->decoded_content;
my $bytes = encode('UTF-8', $xml, Encode::FB_CROAK);
return $parser->parse_iter_from_bytes($bytes);
} elsif ($algebra->silent) {
my $b = Attean::Result->new( bindings => {} );
return Attean::ListIterator->new(variables => [], values => [$b], item_type => 'Attean::API::Result');
} else {
die "Service error: " . $response->status_line;
}
} elsif ($algebra->isa('Attean::Algebra::Graph')) {
my $graph = $algebra->graph;
return $self->evaluate($child, $graph) if ($graph->does('Attean::API::Term'));
my @iters;
my $graphs = $self->model->get_graphs();
my %vars;
while (my $g = $graphs->next) {
next if ($g->value eq $self->default_graph->value);
my $gr = Attean::Result->new( bindings => { $graph->value => $g } );
my $iter = $self->evaluate($child, $g)->map(sub { if (my $result = shift->join($gr)) { return $result } else { return } });
foreach my $v (@{ $iter->variables }) {
$vars{$v}++;
}
push(@iters, $iter);
}
return Attean::IteratorSequence->new( variables => [keys %vars], iterators => \@iters, item_type => 'Attean::API::Result' );
} elsif ($algebra->isa('Attean::Algebra::Group')) {
my @groupby = @{ $algebra->groupby };
my $iter = $self->evaluate($child, $active_graph);
my %groups;
while (my $r = $iter->next) {
my %vars;
my %row_cache;
my @group_terms = map { $expr_eval->evaluate_expression( $_, $r, $active_graph, \%row_cache ) } @groupby;
my $key = join(' ', map { blessed($_) ? $_->as_string : '' } @group_terms);
my %group_bindings;
foreach my $i (0 .. $#group_terms) {
my $v = $groupby[$i];
if (blessed($v) and $v->isa('Attean::ValueExpression') and $v->value->does('Attean::API::Variable') and $group_terms[$i]) {
$group_bindings{$v->value->value} = $group_terms[$i];
}
}
$groups{$key} = [Attean::Result->new( bindings => \%group_bindings ), []] unless (exists($groups{$key}));
push(@{ $groups{$key}[1] }, $r);
}
my @keys = keys %groups;
$groups{''} = [Attean::Result->new( bindings => {} ), []] if (scalar(@keys) == 0);
my $aggs = $algebra->aggregates;
my @results;
my %vars;
foreach my $key (keys %groups) {
my %row_cache;
my ($binding, $rows) = @{ $groups{$key} };
my $count = scalar(@$rows);
my %bindings;
foreach my $i (0 .. $#{ $aggs }) {
my $name = $aggs->[$i]->variable->value;
my $term = $expr_eval->evaluate_expression( $aggs->[$i], $rows, $active_graph, {} );
# warn "AGGREGATE error: $@" if ($@);
$vars{$name}++;
$bindings{ $name } = $term if ($term);
}
push(@results, Attean::Result->new( bindings => \%bindings )->join($binding));
}
return Attean::ListIterator->new(variables => [keys %vars], values => \@results, item_type => 'Attean::API::Result');
} elsif ($algebra->isa('Attean::Algebra::Join')) {
my ($lhs, $rhs) = map { $self->evaluate($_, $active_graph) } @children;
return $lhs->join($rhs);
} elsif ($algebra->isa('Attean::Algebra::LeftJoin')) {
my $expr = $algebra->expression;
my ($lhs_iter, $rhs_iter) = map { $self->evaluate($_, $active_graph) } @children;
my @rhs = $rhs_iter->elements;
my @results;
my %vars = map { $_ => 1 } (@{ $lhs_iter->variables }, @{ $rhs_iter->variables });
while (my $lhs = $lhs_iter->next) {
my $joined = 0;
foreach my $rhs (@rhs) {
if (my $j = $lhs->join($rhs)) {
if ($expr_eval->evaluate_expression( $expr, $j, $active_graph, {} )->ebv) {
$joined++;
push(@results, $j);
}
}
}
push(@results, $lhs) unless ($joined);
}
return Attean::ListIterator->new( variables => [keys %vars], values => \@results, item_type => 'Attean::API::Result');
} elsif ($algebra->isa('Attean::Algebra::Minus')) {
my ($lhsi, $rhs) = map { $self->evaluate($_, $active_graph) } @children;
my @rhs = $rhs->elements;
my @results;
while (my $lhs = $lhsi->next) {
my @compatible;
my @disjoint;
RHS: foreach my $rhs (@rhs) {
if (my $j = $lhs->join($rhs)) {
push(@compatible, 1);
} else {
push(@compatible, 0);
}
my $intersects = 0;
my %lhs_dom = map { $_ => 1 } $lhs->variables;
foreach my $rvar ($rhs->variables) {
if (exists $lhs_dom{$rvar}) {
$intersects = 1;
}
}
push(@disjoint, not($intersects));
}
my $count = scalar(@rhs);
my $keep = 1;
foreach my $i (0 .. $#rhs) {
$keep = 0 unless ($compatible[$i] == 0 or $disjoint[$i] == 1);
}
push(@results, $lhs) if ($keep);
}
return Attean::ListIterator->new( variables => $lhsi->variables, values => \@results, item_type => 'Attean::API::Result');
} elsif ($algebra->isa('Attean::Algebra::Path')) {
my $s = $algebra->subject;
my $path = $algebra->path;
my $o = $algebra->object;
my @children = @{ $path->children };
my ($child) = $children[0];
return $self->model->get_bindings( $s, $path->predicate, $o, $active_graph ) if ($path->isa('Attean::Algebra::PredicatePath'));
if ($path->isa('Attean::Algebra::InversePath')) {
my $path = Attean::Algebra::Path->new( subject => $o, path => $child, object => $s );
return $self->evaluate( $path, $active_graph );
} elsif ($path->isa('Attean::Algebra::AlternativePath')) {
my @children = @{ $path->children };
my @algebras = map { Attean::Algebra::Path->new( subject => $s, path => $_, object => $o ) } @children;
my @iters = map { $self->evaluate($_, $active_graph) } @algebras;
return Attean::IteratorSequence->new( iterators => \@iters, item_type => $iters[0]->item_type, variables => [$algebra->in_scope_variables] );
} elsif ($path->isa('Attean::Algebra::NegatedPropertySet')) {
my $preds = $path->predicates;
my %preds = map { $_->value => 1 } @$preds;
my $filter = $self->model->get_quads($s, undef, $o, $active_graph)->grep(sub {
my $q = shift;
my $p = $q->predicate;
return not exists $preds{ $p->value };
});
my %vars;
$vars{subject} = $s->value if ($s->does('Attean::API::Variable'));
$vars{object} = $o->value if ($o->does('Attean::API::Variable'));
return $filter->map(sub {
my $q = shift;
return unless $q;
my %bindings = map { $vars{$_} => $q->$_() } (keys %vars);
return Attean::Result->new( bindings => \%bindings );
}, 'Attean::API::Result', variables => [values %vars]);
} elsif ($path->isa('Attean::Algebra::SequencePath')) {
if (scalar(@children) == 1) {
my $path = Attean::Algebra::Path->new( subject => $s, path => $children[0], object => $o );
return $self->evaluate($path, $active_graph);
} else {
my @paths;
my $first = shift(@children);
my $join = Attean::Variable->new();
my @new_vars = ($join->value);
push(@paths, Attean::Algebra::Path->new( subject => $s, path => $first, object => $join ));
foreach my $i (0 .. $#children) {
my $newjoin = Attean::Variable->new();
my $obj = ($i == $#children) ? $o : $newjoin;
push(@new_vars, $newjoin->value);
push(@paths, Attean::Algebra::Path->new( subject => $join, path => $children[$i], object => $obj ));
$join = $newjoin;
}
while (scalar(@paths) > 1) {
my ($l, $r) = splice(@paths, 0, 2);
unshift(@paths, Attean::Algebra::Join->new( children => [$l, $r] ));
}
return $self->evaluate(shift(@paths), $active_graph)->map(sub { shift->project_complement(@new_vars) });
}
} elsif ($path->isa('Attean::Algebra::ZeroOrMorePath') or $path->isa('Attean::Algebra::OneOrMorePath')) {
if ($s->does('Attean::API::Term') and $o->does('Attean::API::Variable')) {
my $v = {};
if ($path->isa('Attean::Algebra::ZeroOrMorePath')) {
$self->_ALP($active_graph, $s, $child, $v);
} else {
my $iter = $self->_eval($active_graph, $s, $child);
while (my $n = $iter->next) {
$self->_ALP($active_graph, $n, $child, $v);
}
}
my @results = map { Attean::Result->new( bindings => { $o->value => $_ } ) } (values %$v);
return Attean::ListIterator->new(variables => [$o->value], values => \@results, item_type => 'Attean::API::Result');
} elsif ($s->does('Attean::API::Variable') and $o->does('Attean::API::Variable')) {
my $nodes = $self->model->graph_nodes( $active_graph );
my @results;
while (my $t = $nodes->next) {
my $tr = Attean::Result->new( bindings => { $s->value => $t } );
my $p = Attean::Algebra::Path->new( subject => $t, path => $path, object => $o );
my $iter = $self->evaluate($p, $active_graph);
while (my $r = $iter->next) {
push(@results, $r->join($tr));
}
}
my %vars = map { $_ => 1 } ($s->value, $o->value);
return Attean::ListIterator->new(variables => [keys %vars], values => \@results, item_type => 'Attean::API::Result');
} elsif ($s->does('Attean::API::Variable') and $o->does('Attean::API::Term')) {
my $pp = Attean::Algebra::InversePath->new( children => [$child] );
my $p = Attean::Algebra::Path->new( subject => $o, path => $pp, object => $s );
return $self->evaluate($p, $active_graph);
} else { # Term ZeroOrMorePath(path) Term
my $v = {};
$self->_ALP($active_graph, $s, $child, $v);
my @results;
foreach my $v (values %$v) {
return Attean::ListIterator->new(variables => [], values => [Attean::Result->new()], item_type => 'Attean::API::Result')
if ($v->equals($o));
}
return Attean::ListIterator->new(variables => [], values => [], item_type => 'Attean::API::Result');
}
} elsif ($path->isa('Attean::Algebra::ZeroOrOnePath')) {
my $path = Attean::Algebra::Path->new( subject => $s, path => $child, object => $o );
my @iters;
my %seen;
push(@iters, $self->evaluate( $path, $active_graph )->grep(sub { return not($seen{shift->as_string}++); }));
push(@iters, $self->_zeroLengthPath($s, $o, $active_graph));
my %vars;
foreach my $iter (@iters) {
$vars{$_}++ for (@{ $iter->variables });
}
return Attean::IteratorSequence->new( iterators => \@iters, item_type => 'Attean::API::Result', variables => [keys %vars] );
}
die "Unimplemented path type: $path";
} elsif ($algebra->isa('Attean::Algebra::Project')) {
my $iter = $self->evaluate( $child, $active_graph );
my @vars = map { $_->value } @{ $algebra->variables };
return $iter->map(sub {
my $r = shift;
my $b = { map { my $t = $r->value($_); $t ? ($_ => $t) : () } @vars };
return Attean::Result->new( bindings => $b );
}); #->debug('Project result');
} elsif ($algebra->isa('Attean::Algebra::Slice')) {
my $iter = $self->evaluate( $child, $active_graph );
$iter = $iter->offset($algebra->offset) if ($algebra->offset > 0);
$iter = $iter->limit($algebra->limit) if ($algebra->limit >= 0);
return $iter;
} elsif ($algebra->isa('Attean::Algebra::Union')) {
return Attean::IteratorSequence->new( iterators => [map { $self->evaluate($_, $active_graph) } @children], item_type => 'Attean::API::Result', variables => [$algebra->in_scope_variables] );
} elsif ($algebra->isa('Attean::Algebra::Ask')) {
my $iter = $self->evaluate($child, $active_graph);
my $result = $iter->next;
return Attean::ListIterator->new(values => [$result ? Attean::Literal->true : Attean::Literal->false], item_type => 'Attean::API::Term');
} elsif ($algebra->isa('Attean::Algebra::Construct')) {
my $iter = $self->evaluate($child, $active_graph);
my $patterns = $algebra->triples;
my %seen;
return Attean::CodeIterator->new(
generator => sub {
my $r = $iter->next;
return unless ($r);
my %mapping = map { my $t = $r->value($_); $t ? ("?$_" => $t) : (); } ($r->variables);
my $mapper = Attean::TermMap->rewrite_map(\%mapping);
my @triples;
PATTERN: foreach my $p (@$patterns) {
my @terms = $p->apply_map($mapper)->values;
next PATTERN unless all { $_->does('Attean::API::Term') } @terms;
push(@triples, Attean::Triple->new(@terms));
}
return @triples;
},
item_type => 'Attean::API::Triple'
)->grep(sub { return not($seen{shift->as_string}++); });
} elsif ($algebra->isa('Attean::Algebra::Table')) {
my $vars = [map { $_->value } @{ $algebra->variables }];
return Attean::ListIterator->new(variables => $vars, values => $algebra->rows, item_type => 'Attean::API::Result');
}
die "Unimplemented algebra evaluation for: $algebra";
}
sub _ALP {
my $self = shift;
my $graph = shift;
my $term = shift;
my $path = shift;
my $v = shift;
return if (exists $v->{ $term->as_string });
$v->{ $term->as_string } = $term;
my $iter = $self->_eval($graph, $term, $path);
while (my $n = $iter->next) {
$self->_ALP($graph, $n, $path, $v);
}
}
sub _eval {
my $self = shift;
my $graph = shift;
my $term = shift;
my $path = shift;
my $pp = Attean::Algebra::Path->new( subject => $term, path => $path, object => variable('o') );
my $iter = $self->evaluate($pp, $graph);
my $terms = $iter->map(sub { shift->value('o') }, 'Attean::API::Term');
my %seen;
return $terms->grep(sub { not $seen{ shift->as_string }++ });
}
sub _zeroLengthPath {
my $self = shift;
my $s = shift;
my $o = shift;
my $graph = shift;
my $s_term = ($s->does('Attean::API::Term'));
my $o_term = ($o->does('Attean::API::Term'));
if ($s_term and $o_term) {
my @r;
push(@r, Attean::Result->new()) if ($s->equals($o));
return Attean::ListIterator->new(variables => [], values => \@r, item_type => 'Attean::API::Result');
} elsif ($s_term) {
my $name = $o->value;
my $r = Attean::Result->new( bindings => { $name => $s } );
return Attean::ListIterator->new(variables => [$name], values => [$r], item_type => 'Attean::API::Result');
} elsif ($o_term) {
my $name = $s->value;
my $r = Attean::Result->new( bindings => { $name => $o } );
return Attean::ListIterator->new(variables => [$name], values => [$r], item_type => 'Attean::API::Result');
} else {
my @vars = map { $_->value } ($s, $o);
my $nodes = $self->model->graph_nodes( $graph );
return $nodes->map(
sub {
my $term = shift;
Attean::Result->new( bindings => { map { $_ => $term } @vars } );
},
'Attean::API::Result',
variables => \@vars
);
}
}
}
package Attean::SimpleQueryEvaluator::ExpressionEvaluator 0.030 {
use Moo;
use Attean::RDF;
use Scalar::Util qw(blessed);
use Types::Standard qw(InstanceOf);
use URI::Escape qw(uri_escape_utf8);
use Encode qw(encode);
use POSIX qw(ceil floor);
use Digest;
use UUID::Tiny ':std';
use List::MoreUtils qw(zip);
use DateTime::Format::W3CDTF;
use I18N::LangTags;
use namespace::clean;
has 'evaluator' => (is => 'ro', isa => InstanceOf['Attean::SimpleQueryEvaluator']);
sub evaluate_expression {
my $self = shift;
my $expr = shift;
my $row = shift;
my $active_graph = shift;
my $row_cache = shift || {};
my $impl = $self->impl($expr, $active_graph);
return eval { $impl->($row, row_cache => $row_cache) };
}
sub impl {
my $self = shift;
my $expr = shift;
my $active_graph = shift;
my $op = $expr->operator;
my $true = Attean::Literal->true;
my $false = Attean::Literal->false;
if ($expr->isa('Attean::ExistsExpression')) {
my $pattern = $expr->pattern;
return sub {
my $r = shift;
my $table = Attean::Algebra::Table->new( variables => [map { variable($_) } $r->variables], rows => [$r] );
my $join = Attean::Algebra::Join->new( children => [$table, $pattern] );
# TODO: substitute variables at top-level of EXISTS pattern
my $iter = $self->evaluator->evaluate($join, $active_graph);
return ($iter->next) ? $true : $false;
};
} elsif ($expr->isa('Attean::ValueExpression')) {
my $node = $expr->value;
if ($node->does('Attean::API::Variable')) {
return sub { return shift->value($node->value); };
} else {
return sub { return $node };
}
} elsif ($expr->isa('Attean::UnaryExpression')) {
my ($child) = @{ $expr->children };
my $impl = $self->impl($child, $active_graph);
if ($op eq '!') {
return sub {
my $term = $impl->(@_);
return ($term->ebv) ? $false : $true;
}
} elsif ($op eq '-' or $op eq '+') {
return sub {
my $term = $impl->(@_);
die "TypeError $op" unless (blessed($term) and $term->does('Attean::API::NumericLiteral'));
my $v = $term->numeric_value;
return Attean::Literal->new( value => eval "$op$v", datatype => $term->datatype );
};
}
die "Unimplemented UnaryExpression evaluation: " . $expr->operator;
} elsif ($expr->isa('Attean::BinaryExpression')) {
my ($lhs, $rhs) = @{ $expr->children };
my ($lhsi, $rhsi) = map { $self->impl($_, $active_graph) } ($lhs, $rhs);
if ($op eq '&&') {
return sub {
my ($r, %args) = @_;
my $lbv = eval { $lhsi->($r, %args) };
my $rbv = eval { $rhsi->($r, %args) };
die "TypeError $op" unless ($lbv or $rbv);
return $false if (not($lbv) and not($rbv->ebv));
return $false if (not($rbv) and not($lbv->ebv));
die "TypeError $op" unless ($lbv and $rbv);
return ($lbv->ebv && $rbv->ebv) ? $true : $false;
}
} elsif ($op eq '||') {
return sub {
my ($r, %args) = @_;
my $lbv = eval { $lhsi->($r, %args) };
return $true if ($lbv and $lbv->ebv);
my $rbv = eval { $rhsi->($r, %args) };
die "TypeError $op" unless ($rbv);
return $true if ($rbv->ebv);
return $false if ($lbv);
die "TypeError $op";
}
} elsif ($op =~ m#^(?:[-+*/])$#) { # numeric operators: - + * /
return sub {
my ($r, %args) = @_;
($lhs, $rhs) = map { $_->($r, %args) } ($lhsi, $rhsi);
for ($lhs, $rhs) { die "TypeError $op" unless (blessed($_) and $_->does('Attean::API::NumericLiteral')); }
my $lv = $lhs->numeric_value;
my $rv = $rhs->numeric_value;
return Attean::Literal->new( value => eval "$lv $op $rv", datatype => $lhs->binary_promotion_type($rhs, $op) );
};
} elsif ($op =~ /^!?=$/) {
return sub {
my ($r, %args) = @_;
($lhs, $rhs) = map { $_->($r, %args) } ($lhsi, $rhsi);
for ($lhs, $rhs) { die "TypeError $op" unless (blessed($_) and $_->does('Attean::API::Term')); }
my $ok = ($lhs->equals($rhs));
$ok = not($ok) if ($op eq '!=');
return $ok ? $true : $false;
}
} elsif ($op =~ /^[<>]=?$/) {
return sub {
my ($r, %args) = @_;
($lhs, $rhs) = map { $_->($r, %args) } ($lhsi, $rhsi);
for ($lhs, $rhs) { die "TypeError $op" unless $_->does('Attean::API::Term'); }
my $c = ($lhs->compare($rhs));
return $true if (($c < 0 and ($op =~ /<=?/)) or ($c > 0 and ($op =~ />=?/)) or ($c == 0 and ($op =~ /=/)));
return $false;
}
}
die "Unexpected operator evaluation: $op";
} elsif ($expr->isa('Attean::FunctionExpression')) {
my $func = $expr->operator;
my @children = map { $self->impl($_, $active_graph) } @{ $expr->children };
my %type_roles = qw(URI IRI IRI IRI BLANK Blank LITERAL Literal NUMERIC NumericLiteral);
my %type_classes = qw(URI Attean::IRI IRI Attean::IRI STR Attean::Literal);
return sub {
my ($r, %args) = @_;
my $row_cache = $args{row_cache} || {};
if ($func eq 'IF') {
my $term = $children[0]->( $r, %args );
return ($term->ebv) ? $children[1]->( $r, %args ) : $children[2]->( $r, %args );
} elsif ($func eq 'IN' or $func eq 'NOTIN') {
($true, $false) = ($false, $true) if ($func eq 'NOTIN');
my $child = shift(@children);
my $term = $child->( $r, %args );
foreach my $c (@children) {
if (my $value = eval { $c->( $r, %args ) }) {
return $true if ($term->equals($value));
}
}
return $false;
} elsif ($func eq 'COALESCE') {
foreach my $c (@children) {
my $t = eval { $c->( $r, %args ) };
next if ($@);
return $t if $t;
}
return;
}
my @operands = map { $_->( $r, %args ) } @children;
if ($func =~ /^(STR)$/) {
return $type_classes{$1}->new($operands[0]->value);
} elsif ($func =~ /^([UI]RI)$/) {
my @base = $expr->has_base ? (base => $expr->base) : ();
return $type_classes{$1}->new(value => $operands[0]->value, @base);
} elsif ($func eq 'BNODE') {
if (scalar(@operands)) {
my $name = $operands[0]->value;
if (my $b = $row_cache->{bnodes}{$name}) {
return $b;
} else {
my $b = Attean::Blank->new();
$row_cache->{bnodes}{$name} = $b;
return $b;
}
}
return Attean::Blank->new();
} elsif ($func eq 'LANG') {
die "TypeError: LANG" unless ($operands[0]->does('Attean::API::Literal'));
return Attean::Literal->new($operands[0]->language // '');
} elsif ($func eq 'LANGMATCHES') {
my ($lang, $match) = map { $_->value } @operands;
if ($match eq '*') {
# """A language-range of "*" matches any non-empty language-tag string."""
return ($lang ? $true : $false);
} else {
return (I18N::LangTags::is_dialect_of( $lang, $match )) ? $true : $false;
}
} elsif ($func eq 'DATATYPE') {
return $operands[0]->datatype;
} elsif ($func eq 'BOUND') {
return $operands[0] ? $true : $false;
} elsif ($func eq 'RAND') {
return Attean::Literal->new( value => rand(), datatype => 'http://www.w3.org/2001/XMLSchema#double' );
} elsif ($func eq 'ABS') {
return Attean::Literal->new( value => abs($operands[0]->value), $operands[0]->construct_args );
} elsif ($func =~ /^(?:CEIL|FLOOR)$/) {
my $v = $operands[0]->value;
return Attean::Literal->new( value => (($func eq 'CEIL') ? ceil($v) : floor($v)), $operands[0]->construct_args );
} elsif ($func eq 'ROUND') {
return Attean::Literal->new( value => sprintf('%.0f', (0.000000000000001 + $operands[0]->numeric_value)), $operands[0]->construct_args );
} elsif ($func eq 'CONCAT') {
my $all_lang = 1;
my $all_str = 1;
my $lang;
foreach my $n (@operands) {
die "CONCAT called with a non-literal argument" unless ($n->does('Attean::API::Literal'));
if ($n->datatype->value ne 'http://www.w3.org/2001/XMLSchema#string') {
die "CONCAT called with a datatyped-literal other than xsd:string";
} elsif ($n->language) {
$all_str = 0;
if (defined($lang) and $lang ne $n->language) {
$all_lang = 0;
} else {
$lang = $n->language;
}
} else {
$all_lang = 0;
$all_str = 0;
}
}
my %strtype;
if ($all_lang and $lang) {
$strtype{language} = $lang;
} elsif ($all_str) {
$strtype{datatype} = 'http://www.w3.org/2001/XMLSchema#string'
}
return Attean::Literal->new( value => join('', map { $_->value } @operands), %strtype );
} elsif ($func eq 'SUBSTR') {
my $str = shift(@operands);
my @args = map { $_->numeric_value } @operands;
my $v = scalar(@args == 1) ? substr($str->value, $args[0]-1) : substr($str->value, $args[0]-1, $args[1]);
return Attean::Literal->new( value => $v, $str->construct_args );
} elsif ($func eq 'STRLEN') {
return Attean::Literal->integer(length($operands[0]->value));
} elsif ($func eq 'REPLACE') {
my ($node, $pat, $rep) = @operands;
die "TypeError: REPLACE called without a literal arg1 term" unless (blessed($node) and $node->does('Attean::API::Literal'));
die "TypeError: REPLACE called without a literal arg2 term" unless (blessed($pat) and $pat->does('Attean::API::Literal'));
die "TypeError: REPLACE called without a literal arg3 term" unless (blessed($rep) and $rep->does('Attean::API::Literal'));
die "TypeError: REPLACE called with a datatyped (non-xsd:string) literal" if ($node->datatype and $node->datatype->value ne 'http://www.w3.org/2001/XMLSchema#string');
my ($value, $pattern, $replace) = map { $_->value } @operands;
die "EvaluationError: REPLACE called with unsafe ?{} match pattern" if (index($pattern, '(?{') != -1 or index($pattern, '(??{') != -1);
die "EvaluationError: REPLACE called with unsafe ?{} replace pattern" if (index($replace, '(?{') != -1 or index($replace, '(??{') != -1);
$replace =~ s/\\/\\\\/g;
$replace =~ s/\$(\d+)/\$$1/g;
$replace =~ s/"/\\"/g;
$replace = qq["$replace"];
no warnings 'uninitialized';
$value =~ s/$pattern/"$replace"/eeg;
return Attean::Literal->new(value => $value, $node->construct_args);
} elsif ($func =~ /^[UL]CASE$/) {
return Attean::Literal->new( value => ($func eq 'UCASE' ? uc($operands[0]->value) : lc($operands[0]->value) ), $operands[0]->construct_args );
} elsif ($func eq 'ENCODE_FOR_URI') {
return Attean::Literal->new( uri_escape_utf8($operands[0]->value) );
} elsif ($func eq 'CONTAINS') {
my ($node, $pat) = @operands;
my ($lit, $plit) = map { $_->value } @operands;
die "TypeError: CONTAINS" if ($node->language and $pat->language and $node->language ne $pat->language);
return (index($lit, $plit) >= 0) ? $true : $false;
} elsif ($func eq 'STRSTARTS' or $func eq 'STRENDS') {
my ($lit, $plit) = map { $_->value } @operands;
if ($func eq 'STRENDS') {
my $pos = length($lit) - length($plit);
return (rindex($lit, $plit) == $pos) ? $true : $false;
} else {
return (index($lit, $plit) == 0) ? $true : $false;
}
} elsif ($func eq 'STRBEFORE' or $func eq 'STRAFTER') {
my ($node, $substr) = @operands;
die "$func called without a literal arg1 term" unless (blessed($node) and $node->does('Attean::API::Literal'));
die "$func called without a literal arg2 term" unless (blessed($substr) and $substr->does('Attean::API::Literal'));
die "$func called with a datatyped (non-xsd:string) literal" if ($node->datatype and $node->datatype->value ne 'http://www.w3.org/2001/XMLSchema#string');
my $lhs_simple = (not($node->language) and ($node->datatype->value eq 'http://www.w3.org/2001/XMLSchema#string'));
my $rhs_simple = (not($substr->language) and ($substr->datatype->value eq 'http://www.w3.org/2001/XMLSchema#string'));
if ($lhs_simple and $rhs_simple) {
# ok
} elsif ($node->language and $substr->language and $node->language eq $substr->language) {
# ok
} elsif ($node->language and $rhs_simple) {
# ok
} else {
die "$func called with literals that are not argument compatible";
}
my $value = $node->value;
my $match = $substr->value;
my $i = index($value, $match, 0);
if ($i < 0) {
return Attean::Literal->new('');
} else {
if ($func eq 'STRBEFORE') {
return Attean::Literal->new(value => substr($value, 0, $i), $node->construct_args);
} else {
return Attean::Literal->new(value => substr($value, $i+length($match)), $node->construct_args);
}
}
} elsif ($func =~ /^(?:YEAR|MONTH|DAY|HOURS|MINUTES)$/) {
my $method = lc($func =~ s/^(HOUR|MINUTE)S$/$1/r);
my $dt = $operands[0]->datetime;
return Attean::Literal->integer($dt->$method());
} elsif ($func eq 'SECONDS') {
my $dt = $operands[0]->datetime;
return Attean::Literal->decimal($dt->second());
} elsif ($func eq 'TZ' or $func eq 'TIMEZONE') {
my $dt = $operands[0]->datetime;
my $tz = $dt->time_zone;
if ($tz->is_floating) {
return Attean::Literal->new('') if ($func eq 'TZ');
die "TIMEZONE called with a dateTime without a timezone";
}
return Attean::Literal->new('Z') if ($func eq 'TZ' and $tz->is_utc);
if ($tz) {
my $offset = $tz->offset_for_datetime( $dt );
my $hours = 0;
my $minutes = 0;
my $minus = ($func eq 'TZ') ? '+' : '';
if ($offset < 0) {
$minus = '-';
$offset = -$offset;
}
my $duration = "${minus}PT";
if ($offset >= 60*60) {
my $h = int($offset / (60*60));
$duration .= "${h}H" if ($h > 0);
$hours = int($offset / (60*60));
$offset = $offset % (60*60);
}
if ($offset >= 60) {
my $m = int($offset / 60);
$duration .= "${m}M" if ($m > 0);
$minutes = int($offset / 60);
$offset = $offset % 60;
}
my $seconds = int($offset);
my $s = int($offset);
$duration .= "${s}S" if ($s > 0 or $duration eq 'PT');
return ($func eq 'TZ')
? Attean::Literal->new(sprintf('%s%02d:%02d', $minus, $hours, $minutes))
: Attean::Literal->new( value => $duration, datatype => "http://www.w3.org/2001/XMLSchema#dayTimeDuration");
} else {
return Attean::Literal->new('') if ($func eq 'TZ');
die "TIMEZONE called without a valid dateTime";
}
} elsif ($func eq 'NOW') {
my $value = DateTime::Format::W3CDTF->new->format_datetime( DateTime->now );
return Attean::Literal->new( value => $value, datatype => 'http://www.w3.org/2001/XMLSchema#dateTime' );
} elsif ($func =~ /^(?:STR)?UUID$/) {
return Attean::Literal->new(uc(uuid_to_string(create_uuid()))) if ($func eq 'STRUUID');
return Attean::IRI->new('urn:uuid:' . uc(uuid_to_string(create_uuid())));
} elsif ($func =~ /^(MD5|SHA1|SHA256|SHA384|SHA512)$/) {
my $hash = $func =~ s/SHA/SHA-/r;
my $digest = eval { Digest->new($hash)->add(encode('UTF-8', $operands[0]->value, Encode::FB_CROAK))->hexdigest };
return Attean::Literal->new($digest);
} elsif ($func eq 'STRLANG') {
my ($str, $lang) = @operands;
my @values = map { $_->value } @operands;
die "TypeError: STRLANG must be called with two plain literals" unless (blessed($str) and $str->does('Attean::API::Literal') and blessed($lang) and $lang->does('Attean::API::Literal'));
die "TypeError: STRLANG not called with a simple literal" unless ($str->datatype->value eq 'http://www.w3.org/2001/XMLSchema#string' and not($str->language));
return Attean::Literal->new( value => $values[0], language => $values[1] );
} elsif ($func eq 'STRDT') {
die "TypeError: STRDT" unless ($operands[0]->does('Attean::API::Literal') and not($operands[0]->language));
if (my $dt = $operands[0]->datatype) {
die "TypeError: STRDT" unless ($dt->value eq 'http://www.w3.org/2001/XMLSchema#string');
}
die "TypeError: STRDT" unless ($operands[1]->does('Attean::API::IRI'));
my @values = map { $_->value } @operands;
return Attean::Literal->new( value => $values[0], datatype => $values[1] );
} elsif ($func eq 'SAMETERM') {
my ($a, $b) = @operands;
die "TypeError: SAMETERM" unless (blessed($operands[0]) and blessed($operands[1]));
return $false if ($a->compare($b));
return ($a->value eq $b->value) ? $true : $false;
} elsif ($func =~ /^IS([UI]RI|BLANK|LITERAL|NUMERIC)$/) {
return $operands[0]->does("Attean::API::$type_roles{$1}") ? $true : $false;
} elsif ($func eq 'REGEX') {
my ($value, $pattern) = map { $_->value } @operands;
return ($value =~ /$pattern/) ? $true : $false;
}
die "Unimplemented FunctionExpression evaluation: " . $expr->operator;
};
} elsif ($expr->isa('Attean::AggregateExpression')) {
my $agg = $expr->operator;
my ($child) = @{ $expr->children };
if ($agg eq 'COUNT') {
if ($child) {
my $impl = $self->impl($child, $active_graph);
return sub {
my ($rows, %args) = @_;
my @terms = grep { blessed($_) } map { $impl->($_, %args) } @{ $rows };
if ($expr->distinct) {
my %seen;
@terms = grep { not($seen{$_->as_string}++) } @terms;
}
return Attean::Literal->integer(scalar(@terms));
};
} else {
return sub {
my ($rows, %args) = @_;
return Attean::Literal->integer(scalar(@$rows));
};
}
} elsif ($agg =~ /^(?:SAMPLE|MIN|MAX|SUM|AVG|GROUP_CONCAT)$/) {
my $impl = $self->impl($child, $active_graph);
if ($agg eq 'SAMPLE') {
return sub {
my ($rows, %args) = @_;
return $impl->( shift(@$rows), %args )
};
} elsif ($agg eq 'MIN' or $agg eq 'MAX') {
my $expect = ($agg eq 'MIN') ? 1 : -1;
return sub {
my ($rows, %args) = @_;
my $extrema;
foreach my $r (@$rows) {
my $t = $impl->( $r, %args );
return if (not($t) and $agg eq 'MIN'); # unbound is always minimal
next if (not($t)); # unbound need not be considered for MAX
$extrema = $t if (not($extrema) or $extrema->compare($t) == $expect);
}
return $extrema;
};
} elsif ($agg eq 'SUM' or $agg eq 'AVG') {
return sub {
my ($rows, %args) = @_;
my $count = 0;
my $sum = Attean::Literal->integer(0);
my %seen;
foreach my $r (@$rows) {
my $term = $impl->( $r, %args );
if ($expr->distinct) {
next if ($seen{ $term->as_string }++);
}
if ($term->does('Attean::API::NumericLiteral')) {
$count++;
$sum = Attean::Literal->new( value => ($sum->numeric_value + $term->numeric_value), datatype => $sum->binary_promotion_type($term, '+') );
} else {
die "TypeError: AVG";
}
}
if ($agg eq 'AVG') {
$sum = not($count) ? undef : Attean::Literal->new( value => ($sum->numeric_value / $count), datatype => $sum->binary_promotion_type(Attean::Literal->integer($count), '/') );
}
return $sum;
};
} elsif ($agg eq 'GROUP_CONCAT') {
my $sep = $expr->scalar_vars->{ 'seperator' } // ' ';
return sub {
my ($rows, %args) = @_;
my %seen;
my @strings;
foreach my $r (@$rows) {
my $term = eval { $impl->( $r, %args ) };
if ($expr->distinct) {
next if ($seen{ blessed($term) ? $term->as_string : '' }++);
}
push(@strings, $term->value // '');
}
return Attean::Literal->new(join($sep, sort @strings));
};
}
}
die "Unimplemented AggregateExpression evaluation: " . $expr->operator;
} elsif ($expr->isa('Attean::CastExpression')) {
my ($child) = @{ $expr->children };
my $impl = $self->impl( $child, $active_graph );
my $type = $expr->datatype;
return sub {
my ($r, %args) = @_;
my $term = $impl->($r, %args);
# TODO: reformat syntax for xsd:double
my $cast = Attean::Literal->new( value => $term->value, datatype => $type );
return $cast->canonicalized_term if ($cast->does('Attean::API::CanonicalizingLiteral'));
return $cast;
}
} else {
Carp::confess "No impl for expression " . $expr->as_string;
}
}
}
1;
__END__
=back
=head1 BUGS
Please report any bugs or feature requests to through the GitHub web interface
at L<https://github.com/kasei/attean/issues>.
=head1 SEE ALSO
=head1 AUTHOR
Gregory Todd Williams C<< <gwilliams@cpan.org> >>
=head1 COPYRIGHT
Copyright (c) 2014--2020 Gregory Todd Williams.
This program is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.
=cut
