wikimedia/mediawiki-extensions-Wikibase

<?php

namespace Wikibase\Repo\Rdf;

use InvalidArgumentException;
use Wikibase\DataModel\Services\Lookup\PropertyDataTypeLookup;
use Wikibase\DataModel\Services\Lookup\PropertyDataTypeLookupException;
use Wikibase\DataModel\Snak\PropertyValueSnak;
use Wikibase\DataModel\Snak\Snak;
use Wikimedia\Purtle\RdfWriter;

/**
 * Implementation for RDF mapping for Snaks.
 *
 * @license GPL-2.0-or-later
 * @author Daniel Kinzler
 * @author Stas Malyshev
 */
class SnakRdfBuilder {

    /**
     * @var EntityMentionListener
     */
    private $mentionedEntityTracker;

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

    /**
     * @var ValueSnakRdfBuilder
     */
    private $valueBuilder;

    /**
     * @var PropertyDataTypeLookup
     */
    private $propertyLookup;

    /**
     * @var string[] local data type cache per property id
     */
    private $propertyTypes = [];

    public function __construct(
        RdfVocabulary $vocabulary,
        ValueSnakRdfBuilder $valueBuilder,
        PropertyDataTypeLookup $propertyLookup
    ) {
        $this->vocabulary = $vocabulary;
        $this->valueBuilder = $valueBuilder;
        $this->propertyLookup = $propertyLookup;

        $this->mentionedEntityTracker = new NullEntityMentionListener();
    }

    /**
     * @return EntityMentionListener
     */
    public function getEntityMentionListener() {
        return $this->mentionedEntityTracker;
    }

    public function setEntityMentionListener( EntityMentionListener $mentionedEntityTracker ) {
        $this->mentionedEntityTracker = $mentionedEntityTracker;
    }

    /**
     * Adds the given Statement's main Snak to the RDF graph.
     *
     * @param RdfWriter $writer
     * @param string $snakNamespace
     * @param Snak $snak
     * @param string $propertyNamespace
     * @param string $parentLName the subject owning the Snak (a statement or reference)
     *
     * @throws InvalidArgumentException
     */
    public function addSnak( RdfWriter $writer, $snakNamespace, Snak $snak, $propertyNamespace, string $parentLName ) {
        $propertyId = $snak->getPropertyId();
        switch ( $snak->getType() ) {
            case 'value':
                /** @var PropertyValueSnak $snak */
                '@phan-var PropertyValueSnak $snak';
                $this->addSnakValue( $writer, $snakNamespace, $snak, $propertyNamespace );
                break;
            case 'somevalue':
                $propertyValueLName = $this->vocabulary->getEntityLName( $propertyId );

                $stableBNodeLabel = md5( implode( '-', [ $parentLName, $propertyNamespace, $snakNamespace, $snak->getHash() ] ) );
                $writer->say( $propertyNamespace, $propertyValueLName )->is( '_', $writer->blank( $stableBNodeLabel ) );
                break;
            case 'novalue':
                $propertyValueLName = $this->vocabulary->getEntityLName( $propertyId );
                $propertyRepositoryName = $this->vocabulary->getEntityRepositoryName( $propertyId );

                $writer->say( 'a' )->is(
                    $this->vocabulary->propertyNamespaceNames[$propertyRepositoryName][RdfVocabulary::NSP_NOVALUE],
                    $propertyValueLName
                );
                break;
            default:
                throw new InvalidArgumentException( 'Unknown snak type: ' . $snak->getType() );
        }

        $this->mentionedEntityTracker->propertyMentioned( $snak->getPropertyId() );
    }

    /**
     * Adds the value of the given property to the RDF graph.
     *
     * @param RdfWriter $writer
     * @param string $snakNamespace
     * @param PropertyValueSnak $snak
     * @param string $propertyNamespace The property namespace for this snak
     */
    private function addSnakValue(
        RdfWriter $writer,
        $snakNamespace,
        PropertyValueSnak $snak,
        $propertyNamespace
    ) {
        $propertyId = $snak->getPropertyId();
        $propertyValueLName = $this->vocabulary->getEntityLName( $propertyId );
        $propertyKey = $propertyId->getSerialization();

        // cache data type for all properties we encounter
        if ( !isset( $this->propertyTypes[$propertyKey] ) ) {
            try {
                $this->propertyTypes[$propertyKey] = $this->propertyLookup->getDataTypeIdForProperty( $propertyId );
            } catch ( PropertyDataTypeLookupException $e ) {
                $this->propertyTypes[$propertyKey] = "unknown";
            }
        }

        $dataType = $this->propertyTypes[$propertyKey];
        $this->valueBuilder->addValue( $writer, $propertyNamespace, $propertyValueLName, $dataType, $snakNamespace, $snak );
    }

}