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<?php
namespace SMW\SPARQLStore\QueryEngine\DescriptionInterpreters;
use SMW\Query\Language\ClassDescription;
use SMW\Query\Language\Description;
use SMW\SPARQLStore\QueryEngine\Condition\FalseCondition;
use SMW\SPARQLStore\QueryEngine\Condition\WhereCondition;
use SMW\SPARQLStore\QueryEngine\ConditionBuilder;
use SMW\SPARQLStore\QueryEngine\DescriptionInterpreter;
use SMWDataItem as DataItem;
use SMWExporter as Exporter;
use SMWTurtleSerializer as TurtleSerializer;
/**
* @license GNU GPL v2+
* @since 2.1
*
* @author Markus Krötzsch
* @author mwjames
*/
class ClassDescriptionInterpreter implements DescriptionInterpreter {
/**
* @var ConditionBuilder
*/
private $conditionBuilder;
/**
* @var Exporter
*/
private $exporter;
/**
* @since 2.1
*
* @param ConditionBuilder|null $conditionBuilder
*/
public function __construct( ConditionBuilder $conditionBuilder = null ) {
$this->conditionBuilder = $conditionBuilder;
$this->exporter = Exporter::getInstance();
}
/**
* @since 2.2
*
* {@inheritDoc}
*/
public function canInterpretDescription( Description $description ) {
return $description instanceof ClassDescription;
}
/**
* @since 2.2
*
* {@inheritDoc}
*/
public function interpretDescription( Description $description ) {
$joinVariable = $this->conditionBuilder->getJoinVariable();
$orderByProperty = $this->conditionBuilder->getOrderByProperty();
list( $condition, $namespaces ) = $this->mapCategoriesToConditionElements(
$description->getCategories(),
$description->getHierarchyDepth(),
$joinVariable
);
// empty disjunction: always false, no results to order
if ( $condition === '' ) {
return new FalseCondition();
}
$result = new WhereCondition( $condition, true, $namespaces );
$this->conditionBuilder->addOrderByDataForProperty(
$result,
$joinVariable,
$orderByProperty,
DataItem::TYPE_WIKIPAGE
);
return $result;
}
private function mapCategoriesToConditionElements( array $categories, $depth, $joinVariable ) {
$condition = '';
$namespaces = [];
$instExpElement = $this->exporter->getSpecialPropertyResource( '_INST' );
foreach( $categories as $category ) {
$categoryExpElement = $this->exporter->getResourceElementForWikiPage( $category );
$categoryExpName = TurtleSerializer::getTurtleNameForExpElement( $categoryExpElement );
$namespaces[$categoryExpElement->getNamespaceId()] = $categoryExpElement->getNamespace();
$classHierarchyPattern = $this->tryToAddClassHierarchyPattern(
$category,
$depth,
$categoryExpName
);
$newcondition = $classHierarchyPattern === '' ? "{ " : "{\n" . $classHierarchyPattern;
$newcondition .= "?$joinVariable " . $instExpElement->getQName() . " $categoryExpName . }\n";
if ( $condition === '' ) {
$condition = $newcondition;
} else {
$condition .= "UNION\n$newcondition";
}
}
return [ $condition, $namespaces ];
}
private function tryToAddClassHierarchyPattern( $category, $depth, &$categoryExpName ) {
if ( !$this->conditionBuilder->isSetFlag( SMW_SPARQL_QF_SUBC ) || ( $depth !== null && $depth < 1 ) ) {
return '';
}
if ( $this->conditionBuilder->getHierarchyLookup() === null || !$this->conditionBuilder->getHierarchyLookup()->hasSubcategory( $category ) ) {
return '';
}
$subClassExpElement = $this->exporter->getSpecialPropertyResource( '_SUBC' );
// @see notes in SomePropertyInterpreter
$pathOp = $depth > 1 || $depth === null ? '*' : '?';
$classHierarchyByVariable = "?" . $this->conditionBuilder->getNextVariable( 'sc' );
$condition = "$classHierarchyByVariable " . $subClassExpElement->getQName() . "$pathOp $categoryExpName .\n";
$categoryExpName = "$classHierarchyByVariable";
return $condition;
}
}
|
