SemanticMediaWiki/includes/export/SMW_Exp_Data.php

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<?php
class SMWExpData extends SMWExpElement {
        protected $m_subject;
        protected $m_children = array();
        protected $m_edges = array();

        public function __construct( SMWExpResource $subject ) {
                parent::__construct( $subject->getDataItem() );
                $this->m_subject = $subject;
        }

        public static function makeCollection( array $elements ) {
                if ( count( $elements ) == 0 ) {
                        return new SMWExpData( SMWExporter::getSpecialNsResource( 'rdf', 'nil' ) );
                } else {
                        $rdftype  = SMWExporter::getSpecialNsResource( 'rdf', 'type' );
                        $rdffirst = SMWExporter::getSpecialNsResource( 'rdf', 'first' );
                        $rdfrest  = SMWExporter::getSpecialNsResource( 'rdf', 'rest' );
                        $result = new SMWExpData( new SMWExpResource( '' ) ); // bnode
                        $result->addPropertyObjectValue( $rdftype, new SMWExpData( SMWExporter::getSpecialNsResource( 'rdf', 'List' ) ) );
                        $result->addPropertyObjectValue( $rdffirst, array_shift( $elements ) );
                        $result->addPropertyObjectValue( $rdfrest, SMWExpData::makeCollection( $elements ) );
                        return $result;
                }
        }

        public function getSubject() {
                return $this->m_subject;
        }

        public function addPropertyObjectValue( SMWExpNsResource $property, SMWExpElement $child ) {
                if ( !array_key_exists( $property->getUri(), $this->m_edges ) ) {
                        $this->m_children[$property->getUri()] = array();
                        $this->m_edges[$property->getUri()] = $property;
                }
                $this->m_children[$property->getUri()][] = $child;
        }

        public function getProperties() {
                return $this->m_edges;
        }

        public function getValues( SMWExpResource $property ) {
                if ( array_key_exists( $property->getUri(), $this->m_children ) ) {
                        return $this->m_children[$property->getUri()];
                } else {
                        return array();
                }
        }

        public function getSpecialValues( $namespaceId, $localName ) {
                $pe = SMWExporter::getSpecialNsResource( $namespaceId, $localName );
                return $this->getValues( $pe );
        }

        public function extractMainType() {
                $pe = SMWExporter::getSpecialNsResource( 'rdf', 'type' );
                if ( array_key_exists( $pe->getUri(), $this->m_children ) ) {
                        $result = array_shift( $this->m_children[$pe->getUri()] );
                        if ( count( $this->m_children[$pe->getUri()] ) == 0 ) {
                                unset( $this->m_edges[$pe->getUri()] );
                                unset( $this->m_children[$pe->getUri()] );
                        }
                        return ( $result instanceof SMWExpData ) ? $result->getSubject() : $result;
                } else {
                        return SMWExporter::getSpecialNsResource( 'rdf', 'Resource' );
                }
        }

        public function getCollection() {
                $rdftypeUri  = SMWExporter::getSpecialNsResource( 'rdf', 'type' )->getUri();
                $rdffirstUri = SMWExporter::getSpecialNsResource( 'rdf', 'first' )->getUri();
                $rdfrestUri  = SMWExporter::getSpecialNsResource( 'rdf', 'rest' )->getUri();
                $rdfnilUri   = SMWExporter::getSpecialNsResource( 'rdf', 'nil' )->getUri();
                // first check if we are basically an RDF List:
                if ( ( $this->m_subject->isBlankNode() ) &&
                     ( count( $this->m_children ) == 3 ) &&
                     ( array_key_exists( $rdftypeUri, $this->m_children ) ) &&
                     ( count( $this->m_children[$rdftypeUri] ) == 1 ) &&
                     ( array_key_exists( $rdffirstUri, $this->m_children ) ) &&
                     ( count( $this->m_children[$rdffirstUri] ) == 1 ) &&
                     !( end( $this->m_children[$rdffirstUri] ) instanceof SMWExpLiteral ) &&
                     // (parseType collection in RDF not possible with literals :-/)
                     ( array_key_exists( $rdfrestUri, $this->m_children ) ) &&
                     ( count( $this->m_children[$rdfrestUri] ) == 1 ) ) {
                        $typedata = end( $this->m_children[$rdftypeUri] );
                        $rdflistUri = SMWExporter::getSpecialNsResource( 'rdf', 'List' )->getUri();
                        if ( $typedata->getSubject()->getUri() == $rdflistUri ) {
                                $first = end( $this->m_children[$rdffirstUri] );
                                $rest  = end( $this->m_children[$rdfrestUri] );
                                if ( $rest instanceof SMWExpData ) {
                                        $restlist = $rest->getCollection();
                                        if ( $restlist === false ) {
                                                return false;
                                        } else {
                                                array_unshift( $restlist, $first );
                                                return $restlist;
                                        }
                                } elseif ( ( $rest instanceof SMWExpResource ) &&
                                           ( $rest->getUri() == $rdfnilUri ) )  {
                                        return array( $first );
                                } else {
                                        return false;
                                }
                        } else {
                                return false;
                        }
                } elseif ( ( count( $this->m_children ) == 0 ) && ( $this->m_subject->getUri() == $rdfnilUri ) ) {
                        return array();
                } else {
                        return false;
                }
        }

        public function getTripleList( SMWExpElement $subject = null ) {
                global $smwgBnodeCount;
                if ( !isset( $smwgBnodeCount ) ) {
                        $smwgBnodeCount = 0;
                }

                if ( $subject == null ) {
                        $subject = $this->m_subject;
                }

                $result = array();

                foreach ( $this->m_edges as $key => $edge ) {
                        foreach ( $this->m_children[$key] as $childElement ) {
                                if ( $childElement instanceof SMWExpData ) {
                                        $childSubject = $childElement->getSubject();
                                } else {
                                        $childSubject = $childElement;
                                }

                                if ( ( $childSubject instanceof SMWExpResource ) &&
                                     ( $childSubject->isBlankNode() ) ) { // bnode, rename ID to avoid unifying bnodes of different contexts
                                        // TODO: should we really rename bnodes of the form "_id" here?
                                        $childSubject = new SMWExpResource( '_' . $smwgBnodeCount++, $childSubject->getDataItem() );
                                }

                                $result[] = array( $subject, $edge, $childSubject );
                                if ( $childElement instanceof SMWExpData ) { // recursively add child's triples
                                        $result = array_merge( $result, $childElement->getTripleList( $childSubject ) );
                                }
                        }
                }

                return $result;
        }

}

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