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<?php |
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namespace Asparagus; |
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use InvalidArgumentException; |
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/** |
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* Abstraction layer to create graphs for SPARQL queries |
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* |
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* @todo support filter, optional, union, minus |
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* |
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* @since 0.3 (package-private since 0.1) |
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* |
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* @license GNU GPL v2+ |
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* @author Bene* < [email protected] > |
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*/ |
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class GraphBuilder { |
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/** |
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* @var array nested list of conditions, grouped by subject and predicate |
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*/ |
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private $conditions = array(); |
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/** |
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* @var string[] list of optional expressions |
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*/ |
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private $optionals = array(); |
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/** |
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* @var string[] list of filter expressions |
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*/ |
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private $filters = array(); |
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/** |
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* @var string[] list of unions |
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*/ |
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private $unions = array(); |
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/** |
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* @var string[] list of subqueries |
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*/ |
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private $subqueries = array(); |
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/** |
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* @var string |
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*/ |
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private $currentSubject = null; |
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/** |
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* @var string |
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*/ |
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private $currentPredicate = null; |
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/** |
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* @var ExpressionValidator |
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*/ |
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private $expressionValidator; |
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/** |
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* @var UsageValidator |
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*/ |
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private $usageValidator; |
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/** |
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* Package-private constructor, use QueryBuilder::newSubgraph instead |
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* |
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* @param UsageValidator $usageValidator |
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* @throws InvalidArgumentException |
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*/ |
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public function __construct( UsageValidator $usageValidator ) { |
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$this->expressionValidator = new ExpressionValidator(); |
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$this->usageValidator = $usageValidator; |
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} |
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/** |
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* Adds the given triple as a condition. |
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* |
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* @param string $subject |
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* @param string $predicate |
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* @param string $object |
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* @return self |
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* @throws InvalidArgumentException |
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*/ |
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public function where( $subject, $predicate, $object ) { |
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$this->expressionValidator->validate( $subject, |
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ExpressionValidator::VALIDATE_VARIABLE | ExpressionValidator::VALIDATE_PREFIXED_IRI |
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); |
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$this->expressionValidator->validate( $predicate, |
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ExpressionValidator::VALIDATE_VARIABLE | ExpressionValidator::VALIDATE_PATH |
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); |
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$this->expressionValidator->validate( $object, |
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ExpressionValidator::VALIDATE_VARIABLE | ExpressionValidator::VALIDATE_PREFIXED_IRI | ExpressionValidator::VALIDATE_NATIVE |
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); |
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$this->usageValidator->trackUsedPrefixes( $subject . ' ' . $predicate . ' ' . $object ); |
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$this->usageValidator->trackDefinedVariables( $subject . ' ' . $predicate . ' ' . $object ); |
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$this->currentSubject = $subject; |
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$this->currentPredicate = $predicate; |
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$this->conditions[$subject][$predicate][] = $object; |
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return $this; |
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} |
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/** |
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* Adds the given triple/double/single value as an additional condition |
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* to the previously added condition. |
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* |
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* @param string $subject |
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* @param string|null $predicate |
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* @param string|null $object |
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* @return self |
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* @throws InvalidArgumentException |
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*/ |
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public function also( $subject, $predicate = null, $object = null ) { |
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if ( $predicate === null ) { |
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$this->where( $this->currentSubject, $this->currentPredicate, $subject ); |
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} else if ( $object === null ) { |
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$this->where( $this->currentSubject, $subject, $predicate ); |
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} else { |
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$this->where( $subject, $predicate, $object ); |
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} |
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return $this; |
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} |
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/** |
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* Adds the given expression as a filter to this query. |
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* |
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* @param string $expression |
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* @return self |
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* @throws InvalidArgumentException |
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*/ |
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public function filter( $expression ) { |
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$this->expressionValidator->validate( $expression, ExpressionValidator::VALIDATE_FUNCTION ); |
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$this->usageValidator->trackUsedPrefixes( $expression ); |
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$this->usageValidator->trackUsedVariables( $expression ); |
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$this->filters[] = '(' . $expression . ')'; |
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return $this; |
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} |
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/** |
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* Adds a filter that the given graph or triple exists. |
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* |
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* @param string|GraphBuilder $subject |
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* @param string|null $predicate |
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* @param string|null $object |
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* @return self |
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* @throws InvalidArgumentException |
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*/ |
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public function filterExists( $subject, $predicate = null, $object = null ) { |
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$graphBuilder = $this->getGraphBuilder( $subject, $predicate, $object ); |
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$this->filters[] = 'EXISTS {' . $graphBuilder->getSPARQL() . ' }'; |
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return $this; |
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} |
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/** |
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* Adds a filter that the given graph or triple does not exist. |
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* |
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* @param string|GraphBuilder $subject |
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* @param string|null $predicate |
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* @param string|null $object |
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* @return self |
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* @throws InvalidArgumentException |
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*/ |
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public function filterNotExists( $subject, $predicate = null, $object = null ) { |
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$graphBuilder = $this->getGraphBuilder( $subject, $predicate, $object ); |
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$this->filters[] = 'NOT EXISTS {' . $graphBuilder->getSPARQL() . ' }'; |
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return $this; |
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} |
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/** |
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* Adds the given graph or triple as an optional condition. |
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* |
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* @param string|GraphBuilder $subject |
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* @param string|null $predicate |
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* @param string|null $object |
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* @return self |
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* @throws InvalidArgumentException |
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*/ |
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public function optional( $subject, $predicate = null, $object = null ) { |
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$graphBuilder = $this->getGraphBuilder( $subject, $predicate, $object ); |
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$this->optionals[] = $graphBuilder->getSPARQL(); |
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return $this; |
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} |
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private function getGraphBuilder( $subject, $predicate, $object ) { |
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if ( $subject instanceof GraphBuilder ) { |
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return $subject; |
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} |
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$graphBuilder = new GraphBuilder( $this->usageValidator ); |
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return $graphBuilder->where( $subject, $predicate, $object ); |
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} |
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/** |
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* Adds the given graphs as alternative conditions. |
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* |
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* @param GraphBuilder|GraphBuilder[] $graphs |
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* @return self |
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* @throws InvalidArgumentException |
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*/ |
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public function union( $graphs /* graphs ... */ ) { |
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$graphs = is_array( $graphs ) ? $graphs : func_get_args(); |
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$this->unions[] = implode( ' UNION', array_map( function( GraphBuilder $graph ) { |
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return ' {' . $graph->getSPARQL() . ' }'; |
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}, $graphs ) ); |
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return $this; |
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} |
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/** |
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* Adds the given subquery. |
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* |
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* @param QueryBuilder $queryBuilder |
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* @return self |
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* @throws InvalidArgumentException |
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*/ |
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public function subquery( QueryBuilder $queryBuilder ) { |
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$this->subqueries[] = $queryBuilder->getSPARQL( false ); |
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$this->usageValidator->trackDefinedVariables( implode( ' ', $queryBuilder->getSelects() ) ); |
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// @todo temp hack to add AS definitions to defined variables |
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$regexHelper = new RegexHelper(); |
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$matches = $regexHelper->getMatches( 'AS \{variable}', implode( ' ', $queryBuilder->getSelects() ) ); |
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$this->usageValidator->trackDefinedVariables( $matches ); |
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return $this; |
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} |
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/** |
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* Returns the plain SPARQL string of these conditions. |
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* Surrounding brackets are not included. |
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* |
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* @return string |
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*/ |
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public function getSPARQL() { |
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// add subqueries to the beginning because they are logically evaluated first |
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$sparql = $this->formatSubqueries(); |
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foreach ( $this->conditions as $subject => $predicates ) { |
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$sparql .= ' ' . $subject; |
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$sparql .= $this->formatPredicates( $predicates ) . ' .'; |
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} |
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$sparql .= $this->formatOptionals(); |
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$sparql .= $this->formatFilters(); |
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$sparql .= $this->formatUnions(); |
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return $sparql; |
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} |
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private function formatPredicates( array $predicates ) { |
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return implode( ' ;', array_map( function( $predicate, $objects ) { |
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return ' ' . $predicate . ' ' . implode( ' , ', $objects ); |
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}, array_keys( $predicates ), $predicates ) ); |
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} |
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private function formatOptionals() { |
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return implode( array_map( function( $optional ) { |
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return ' OPTIONAL {' . $optional . ' }'; |
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}, $this->optionals ) ); |
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} |
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private function formatFilters() { |
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return implode( array_map( function( $filter ) { |
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return ' FILTER ' . $filter; |
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}, $this->filters ) ); |
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} |
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private function formatUnions() { |
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return implode( $this->unions ); |
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} |
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private function formatSubqueries() { |
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return implode( array_map( function( $subquery ) { |
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return ' { ' . $subquery . ' }'; |
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}, $this->subqueries ) ); |
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} |
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} |
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