rdfio/RDFIO

<?php

if ( !defined( 'MEDIAWIKI' ) ) {
    die( 'Not a valid entry point.' );
}

global $IP;

/**
 * SMWARC2Store extends SMWSQLStore3 and forwards all update/delete to ARC2 via SPARQL+
 * queries. The class was based on JosekiStore in the SparqlExtension, which in turn is
 * loosely based on/insipred by RAPStore.
 * @author samuel.lampa@gmail.com
 * @package RDFIO
 */
class SMWARC2Store extends SMWSQLStore3 {
    protected $arc2store;

    public function __construct() {
        global $wgDBserver, $wgDBname, $wgDBuser, $wgDBpassword, $wgDBprefix;
        parent::__construct();
        // Customize these details if you
        // want to use an external database
        $arc2StoreConfig = array(
            'db_host' => $wgDBserver,
            'db_name' => $wgDBname,
            'db_user' => $wgDBuser,
            'db_pwd' => $wgDBpassword,
            'store_name' => $wgDBprefix . 'arc2store', // Determines table prefix
        );
        $this->arc2store = ARC2::getStore( $arc2StoreConfig );
    }

    /**
     * wraps removeDataForURI()
     * @param $subject
     */
    public function deleteSubject( Title $subject ) {
        $subjectUri = SMWExporter::getInstance()->expandURI( $this->getURI( $subject ) );
        $this->removeDataForURI( $subjectUri );

        return parent::deleteSubject( $subject ); // Also update via SQLStore3
    }

    /**
     * Does update. First deletes, then inserts.
     * @param $data
     */
    public function updateData( SMWSemanticData $data ) {
        // NOTE: Should doDataUpdate() be used instead? (See SMWStore class)
        $exportData = SMWExporter::getInstance()->makeExportData( $data );
        $subjectUri = SMWExporter::getInstance()->expandURI( $exportData->getSubject()->getUri() );

        $this->removeDataForURI( $subjectUri );
        $tripleList = $exportData->getTripleList();

        $sparqlUpdateText = "INSERT INTO <> {\n"; // Follows ARC2 SPARQL+ syntax (not SPARQL Update)
        foreach ( $tripleList as $triple ) {
            $subject = $triple[0];
            $predicate = $triple[1];
            $object = $triple[2];

            $objectStr = '';
            $subjectStr = '';
            $predicateStr = '';

            if ( $object instanceof SMWExpLiteral ) {
                // NOTE: Add escaping for results of getLexicalForm()?
                $objectStr = '"' . $object->getLexicalForm() . '"' . ( ( $object->getDatatype() == '' ) ? '' : '^^<' . $object->getDatatype() . '>' );
            } elseif ( $object instanceof SMWExpResource ) {
                $objectStr = '<' . SMWExporter::getInstance()->expandURI( $object->getUri() ) . '>';
            } else {
                $objectStr = '""';
            }

            if ( $subject instanceof SMWExpResource ) {
                $subjectStr = '<' . SMWExporter::getInstance()->expandURI( $subject->getUri() ) . '>';
            }

            if ( $predicate instanceof SMWExpResource ) {
                $predicateStr = '<' . SMWExporter::getInstance()->expandURI( $predicate->getUri() ) . '>';
            }

            $sparqlUpdateText .= $subjectStr . ' ' . $predicateStr . ' ' . $objectStr . " .\n";
        }
        $sparqlUpdateText .= "}\n";

        wfDebugLog( 'SPARQL_LOG', $sparqlUpdateText );
        $this->executeArc2Query( $sparqlUpdateText );
        parent::updateData( $data );
    }

    /**
     * Move/rename page
     * @param $oldtitle
     * @param $newtitle
     * @param $pageid
     * @param $redirid
     */
    public function changeTitle( Title $oldTitle, Title $newTitle, $pageId, $redirectId = 0 ) {
        // Save it in parent store now!
        // We need that so we get all information correctly!
        parent::changeTitle( $oldTitle, $newTitle, $pageId, $redirectId );

        // Delete old stuff
        $oldUri = SMWExporter::getInstance()->expandURI( $this->getURI( $oldTitle ) );
        $this->removeDataForURI( $oldUri );

        $newpage = SMWDataValueFactory::newTypeIDValue( '_wpg' );
        $newpage->setValues( $newTitle->getDBkey(), $newTitle->getNamespace(), $pageId );
        $semdata = $this->getSemanticData( $newpage );
        $this->updateData( $semdata );

        $oldpage = SMWDataValueFactory::newTypeIDValue( '_wpg' );
        $oldpage->setValues( $oldTitle->getDBkey(), $oldTitle->getNamespace(), $redirectId );
        $semdata = $this->getSemanticData( $oldpage );
        $this->updateData( $semdata, false );
    }

    /**
     * Communicates with ARC2 RDF Store
     * @param $requestString
     */
    public function executeArc2Query( $requestString ) {

        $query = $requestString;
        $result = $this->arc2store->query( $query );

        $errors = $this->arc2store->getErrors();
        foreach ( $errors as $error ) {
            throw new RDFIOARC2StoreException( $error );
        }

        return $result;
    }

    /**
     * Insert new pages into endpoint. Used to import data.
     * @param $title
     */
    private function insertData( Title $title, $pageid ) {
        $newpage = SMWDataValueFactory::newTypeIDValue( '_wpg' );
        $newpage->setValues( $title->getDBkey(), $title->getNamespace(), $pageid );
        $semdata = $this->getSemanticData( $newpage );
        $this->updateData( $semdata );
    }

    /**
     * deletes triples that have $uri as subject
     * @param $uri
     */
    private function removeDataForURI( $uri ) {
        $sparqlUpdateText = 'DELETE { <' . $uri . '> ?x ?y . }';
        $response = $this->executeArc2Query( $sparqlUpdateText );
        return $response;
    }

    /**
     * Having a title of a page, what is the URI that is described by that page?
     * The result still requires expandURI()
     * @param string $title
     * @return string $uri
     */
    private function getURI( $title ) {
        $uri = '';
        if ( $title instanceof Title ) {
            $wikiPageDI = SMWDIWikiPage::newFromTitle( $title );
            $exp = SMWExporter::getInstance()->makeExportDataForSubject( $wikiPageDI );
            $uri = $exp->getSubject()->getUri();
        } else {
            // There could be other types as well that we do NOT handle here
        }

        return $uri; // still requires expandURI()
    }
}

class RDFIOARC2StoreException extends MWException {
}