1 files changed, 140 insertions, 0 deletions
diff --git a/www/wiki/extensions/SemanticMediaWiki/src/SPARQLStore/QueryEngine/DescriptionInterpreters/ClassDescriptionInterpreter.php b/www/wiki/extensions/SemanticMediaWiki/src/SPARQLStore/QueryEngine/DescriptionInterpreters/ClassDescriptionInterpreter.php
new file mode 100644
index 00000000..8edc933e
--- /dev/null
+++ b/www/wiki/extensions/SemanticMediaWiki/src/SPARQLStore/QueryEngine/DescriptionInterpreters/ClassDescriptionInterpreter.php
@@ -0,0 +1,140 @@
+<?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;
+	}
+
+}