rdfio/RDFIO

<?php

/**
 * RDFIOARC2StoreWrapper contains utility functionality that requires connecting to the
 * ARC2 triplestore (Not to confuse with the RDFIOARC2Store, which is an implementation
 * of SMWStore "interface". Here we're wrapping some direct queries to the ARC2 triplestore.
 * @author samuel.lampa@gmail.com
 * @package RDFIO
 */
class RDFIOARC2StoreWrapper {
    protected $arc2store;
    protected $uriResolverUrl;

    const EQUIV_URI = 'http://www.w3.org/2002/07/owl#sameAs';
    const EQUIV_PROPERTY_URI = 'http://www.w3.org/2002/07/owl#equivalentProperty';

    function __construct( $tripleStore = null ) {
        global $wgDBserver, $wgDBname, $wgDBuser, $wgDBpassword, $wgDBprefix;
        $this->uriResolverUrl = '';
        if ( !is_null( $tripleStore ) ) {
            $this->arc2store = $tripleStore;
            return;
        }
        $arc2StoreConfig = array(
            'db_host' => $wgDBserver,
            'db_name' => $wgDBname,
            'db_user' => $wgDBuser,
            'db_pwd' => $wgDBpassword,
            'store_name' => preg_replace( '/s?unittest_/', '', $wgDBprefix ) . 'arc2store', // Determines table prefix
        );
        $this->arc2store = ARC2::getStore( $arc2StoreConfig );
    }

    /**
     * For all property URIs and all subject and objects which have URIs, add
     * triples using equivalent uris for these URIs (in all combinations
     * thereof). If $propUrisFilter is set, allow only triples with properties
     * included in this filter array.
     * @param array $triples
     * @param array $propUrisFilter
     * @return array $triples
     */
    function toEquivUrisInTriples( $triples, $propUrisFilter = null ) {

        $equivUriCache = array();

        foreach ( $triples as $tripleidx => $triple ) {
            // Subject
            $subjUri = $triple['s'];
            if ( array_key_exists( $subjUri, $equivUriCache ) ) {
                $triples[$tripleidx]['s'] = $equivUriCache[$subjUri];
            } else {
                $subjEquivUris = $this->getEquivURIsForURI( $subjUri );
                if ( count( $subjEquivUris ) > 0 ) {
                    $triples[$tripleidx]['s'] = $subjEquivUris[0];
                    $equivUriCache[$subjUri] = $subjEquivUris[0];
                }
            }

            // Property
            $propUri = $triple['p'];
            if ( array_key_exists( $propUri, $equivUriCache ) ) {
                $triples[$tripleidx]['p'] = $equivUriCache[$propUri];
            } else {
                $propEquivUris = $this->getEquivURIsForURI( $triple['p'] );
                if ( !is_null( $propUrisFilter ) ) {
                    // Only include URIs that occur in the filter
                    $propEquivUris = array_intersect( $propEquivUris, $propUrisFilter );
                }
                if ( count( $propEquivUris ) > 0 ) {
                    $triples[$tripleidx]['p'] = $propEquivUris[0];
                    $equivUriCache[$propUri] = $propEquivUris[0];
                }
            }

            // Object
            if ( $triple['o_type'] === 'uri' ) {
                $objUri = $triple['o'];
                if ( array_key_exists( $objUri, $equivUriCache ) ) {
                    $triples[$tripleidx]['o'] = $equivUriCache[$objUri];
                } else {
                    $objEquivUris = $this->getEquivURIsForURI( $objUri );
                    if ( count( $objEquivUris ) > 0 ) {
                        $triples[$tripleidx]['o'] = $objEquivUris[0];
                        $equivUriCache[$objUri] = $objEquivUris[0];
                    }
                }
            }
        }

        return $triples;
    }

    /**
     * For a given RDF URI, return it's corresponding equivalend URIs
     * as defined in wiki articles by the Equivalent URI property
     * @param string $uri
     * @param boolean $isProperty
     * @return array $equivUris
     */
    public function getEquivURIsForURI( $uri ) {
        $equivUris = array();

        $query = 'SELECT ?equivUri WHERE { { <' . $uri . '> <' . self::EQUIV_URI . '> ?equivUri } UNION { <' . $uri . '> <' . self::EQUIV_PROPERTY_URI . '> ?equivUri } }';
        $results = $this->arc2store->query( $query );

        if ( $this->arc2store->getErrors() ) {
            foreach ( $this->arc2store->getErrors() as $error ) {
                throw new RDFIOARC2StoreWrapperException( $error );
            }
            return;
        }

        $rows = $results['result']['rows'];

        if ( count( $rows ) > 0 ) {
            foreach ( $rows as $equivUriId => $equivUri ) {
                $equivUris[$equivUriId] = $equivUri['equivUri'];
            }
        }

        return $equivUris;
    }

    /**
     * Given an Equivalent URI (as defined in a wiki article, return the URI used by SMW
     * @param string $equivUri
     * @return string $uri
     */
    public function getURIForEquivURI( $equivUri, $isProperty = false ) {
        $uri = '';
        if ( $isProperty ) {
            $equivUriUri = self::EQUIV_PROPERTY_URI;
        } else {
            $equivUriUri = self::EQUIV_URI;
        }
        $query = 'SELECT ?uri WHERE { ?uri <' . $equivUriUri . '> <' . $equivUri . '> }';
        $results = $this->arc2store->query( $query );

        if ( !$this->arc2store->getErrors() ) {
            $rows = $results['result']['rows'];
            if ( count( $rows ) > 0 ) {
                $row = $rows[0];
                $uri = $row['uri'];
            }
        } else {
            foreach ( $this->arc2store->getErrors() as $error ) {
                throw new RDFIOARC2StoreWrapperException( $error );
            }
        }
        return $uri;
    }

    /**
     * For a URI that is defined using the "Original URI" property, return the wiki
     * article corresponding to that entity
     * @param string $uri
     * @return string $wikititle;
     */
    public function getWikiTitleByEquivalentURI( $uri, $isProperty = false ) {
        $uriEncoded = str_replace( ' ', '%20', $uri );
        $internalUri = $this->getURIForEquivURI( $uriEncoded, $isProperty );
        $internalUriDecoded = SMWExporter::getInstance()->decodeURI( $internalUri );

        // Remove URI parts, so that we get a clean title
        $uriParts = explode( '/', rtrim( $internalUriDecoded, '/' ) );
        $wikiTitle = str_replace( '_', ' ', array_pop( $uriParts ) );

        if ( $wikiTitle != '' && $isProperty  ) {
            $propertyNS = Title::newFromDBkey( $wikiTitle )->getNsText();
            $wikiTitle = str_replace( $propertyNS . ':', '', $wikiTitle );
        }

        return $wikiTitle;
    }

    /////// Utility methods ///////

    /**
     * Get SMWs internal URI for corresponding to the "Equivalent URI" property
     * @return string
     */
    public function getEquivURIURI() {
        // return $this->getURIResolverURI() . 'Property-3AEquivalent_URI';
        return self::EQUIV_URI;
    }

    /**
     * Get SMWs internal URI for corresponding to the "Equivalent URI" property,
     * for property pages
     * @return string
     */
    public function getEquivPropertyURIURI() {
        return self::EQUIV_PROPERTY_URI;
    }

}


class RDFIOARC2StoreWrapperException extends MWException {
}