wikimedia/mediawiki-extensions-Wikibase

<?php

namespace Wikibase\Repo\Rdf\Values;

use DataValues\DataValue;
use Wikibase\Repo\Rdf\DedupeBag;
use Wikibase\Repo\Rdf\HashDedupeBag;
use Wikibase\Repo\Rdf\RdfVocabulary;
use Wikimedia\Purtle\RdfWriter;

/**
 * Helper object for mapping DataValues to complex RDF structures (value nodes).
 *
 * @license GPL-2.0-or-later
 * @author Daniel Kinzler
 * @author Stas Malyshev
 */
class ComplexValueRdfHelper {

    /**
     * @var RdfVocabulary
     */
    private $vocabulary;

    /**
     * @var DedupeBag
     */
    private $dedupeBag;

    /**
     * @var RdfWriter
     */
    private $valueNodeWriter;

    /**
     * @param RdfVocabulary $vocabulary
     * @param RdfWriter $valueNodeWriter
     * @param DedupeBag|null $dedupeBag
     */
    public function __construct( RdfVocabulary $vocabulary, RdfWriter $valueNodeWriter, DedupeBag $dedupeBag = null ) {
        $this->valueNodeWriter = $valueNodeWriter;
        $this->vocabulary = $vocabulary;
        $this->dedupeBag = $dedupeBag ?: new HashDedupeBag();
    }

    /**
     * @return RdfWriter
     */
    public function getValueNodeWriter() {
        return $this->valueNodeWriter;
    }

    /**
     * Creates a value node for $value, and attaches it to the current subject of $writer.
     * If a value node for $value was already created, null is returned. Otherwise, the
     * value node's lname is returned, which should be used to generate detailed about the
     * value into the writer returned by getValueNodeWriter().
     *
     * When this method returns a non-null lname, the current subject of the RdfWriter returned by
     * getValueNodeWriter() will the be value node with that lname.
     *
     * @param RdfWriter $writer
     * @param string $propertyValueNamespace Property value relation namespace
     * @param string $propertyValueLName Property value relation name
     * @param string $dataType Property data type (unused, passed here for symmetry
     *        with the signature of ValueSnakRdfBuilder::addValue).
     * @param string $snakNamespace
     * @param DataValue $value
     * @param bool $normalized Is this a normalized value?
     *
     * @return string|null The LName of the value node (in the RdfVocabulary::NS_VALUE namespace),
     *  or null if the value node should not be processed (generally, because it already has
     *  been processed).
     */
    public function attachValueNode(
        RdfWriter $writer,
        $propertyValueNamespace,
        $propertyValueLName,
        $dataType,
        $snakNamespace,
        DataValue $value,
        $normalized = false
    ) {
        // @phan-suppress-next-line PhanUndeclaredMethod
        $valueLName = $value->getHash();

        $namespaces =
            $normalized ? $this->vocabulary->claimToValueNormalized : $this->vocabulary->claimToValue;

        $writer->say( $namespaces[$propertyValueNamespace], $propertyValueLName )
            ->is( $snakNamespace, $valueLName );

        if ( $this->dedupeBag->alreadySeen( $valueLName, 'V' ) !== false ) {
            return null;
        }

        $this->valueNodeWriter->about( $snakNamespace, $valueLName )
            ->a( RdfVocabulary::NS_ONTOLOGY, $this->vocabulary->getValueTypeName( $value ) );

        return $valueLName;
    }

}