source: Dev/trunk/rdfapi/dataset/IteratorFindQuadsMem.php @ 12

<?php
require_once RDFAPI_INCLUDE_DIR . 'dataset/Quad.php';
// ----------------------------------------------------------------------------------
// Class: IteratorFindQuadsMem
// ----------------------------------------------------------------------------------



/**
* Implementation of a quad iterator.
*
* This Iterator should be used like:
* for($iterator = $dataset->findInNamedGraphs(null,null,null,null); $iterator->valid(); $iterator->next())
* {
*       $currentQuad=$it->current();
* };
*
* @version  $Id$
* @author Daniel Westphal (http://d-westphal.de)
*
*
* @package      dataset
* @access       public
**/
class IteratorFindQuadsMem
{
        /**
        * key value in the current graph.
        *
        * @var   dataset
        * @access       private
        */
        var $graphKey;

        /**
        * boolean value, if the results should be returned as triples.
        *
        * @var          boolean
        * @access       private
        */
        var $returnAsTriples;

        /**
        * The current position.
        *
        * @var          integer
        * @access       private
        */
        var $key;

        /**
        * If the current resource is valid.
        *
        * @var          boolean
        * @access       private
        */
        var $valid;

        /**
        * The current NamedGraph.
        *
        * @var  NamedGraph
        * @access       private
        */
        var $current;

        /**
        * The graphName Resource to search for.
        *
        * @var string
        * @access       private
        */
        var $findGraphName;

        /**
        * The subject Resource to search for.
        *
        * @var string
        * @access       private
        */
        var $findSubject;

        /**
        * The predicate Resource to search for.
        *
        * @var string
        * @access       private
        */
        var $findPredicate;

        /**
        * The object Resource to search for.
        *
        * @var string
        * @access       private
        */
        var $findObject;

        /**
        * Iterator over all graphs of the RDF dataset.
        *
        * @var string
        * @access       private
        */
        var $graphIterator;


        /**
    * Constructor.
    *
        * $subject, $predicate, and $object are used like find().
        * $getSPO supports the strings 's', 'p', and 'o' to return
        * either the subject, predicate, or object of the result statements.
        *
    *
    * @param Resource
    * @param Resource
    * @param Resource
    * @param dataset
    * @param Boolean
        * @access       public
    */
        function IteratorFindQuadsMem($subject,$predicate,$object,&$graphIterator, $returnAsTriples=false)
        {
                $this->findSubject=$subject;
                $this->findPredicate=$predicate;
                $this->findObject=$object;
                $this->graphIterator=&$graphIterator;
                $this->rewind();
                $this->returnAsTriples=$returnAsTriples;
        }

        /**
    * Resets iterator list to start.
    *
        * @access       public
    */
        function rewind()
        {
                $this->graphIterator->rewind();
                $this->key = -1;
                $this->graphKey=-1;
                $this->next();
        }

        /**
    * Says if there are additional items left in the list.
    *
    * @return   boolean
        * @access       public
    */
        function valid()
        {
                return $this->valid;
        }

        /**
    * Moves Iterator to the next item in the list.
    *
        * @access       public
    */
        function next()
        {
                if($this->graphIterator->valid()===false)
                {
                        $this->valid=false;
                        return;
                }

                $currentGraph=&$this->graphIterator->current();
                $this->current= $currentGraph->findFirstMatchingStatement($this->findSubject,$this->findPredicate,$this->findObject,++$this->graphKey);
                if($this->current==null)
                {
                        do
                        {
                                $this->graphIterator->next();
                                if($this->graphIterator->valid()===false)
                                {
                                        $this->valid=false;
                                        return;
                                }
                                $currentGraph=&$this->graphIterator->current();
                                $this->graphKey=-1;
                                $this->current= $currentGraph->findFirstMatchingStatement($this->findSubject,$this->findPredicate,$this->findObject,++$this->graphKey);

                        } while ($this->current==null);
                }
                $this->key++;
                $this->valid=true;
        }

        /**
    * Returns the current item.
    *
    * @return   mixed
        * @access       public
    */
        function current()
        {
                if($this->returnAsTriples) return $this->current;

                $currentGraph=&$this->graphIterator->current();
                return new Quad(new Resource($currentGraph->getGraphName()),$this->current->getSubject(),$this->current->getPredicate(),$this->current->getObject());
        }

        /**
    * Returns the key of the current item.
    *
    * @return   integer
        * @access       public
    */
        function key()
        {
                return $this->key;
        }
}
?>