source: Dev/trunk/rdfapi/dataset/DatasetMem.php @ 247

<?php
require_once RDFAPI_INCLUDE_DIR . 'dataset/Dataset.php';
require_once RDFAPI_INCLUDE_DIR . 'dataset/NamedGraphMem.php';
require_once RDFAPI_INCLUDE_DIR . 'model/MemModel.php';
// ----------------------------------------------------------------------------------
// Class: DatasetMem
// ----------------------------------------------------------------------------------

/**
* In-memory implementation of a RDF dataset.
* A RDF dataset set is a collection of named RDF graphs.
*
* @version  $Id$
* @author Daniel Westphal (http://www.d-westphal.de)
* @author Chris Bizer <chris@bizer.de>
*
* @package      dataset
* @access       public
**/

class DatasetMem extends Dataset
{

        /**
        * Reference to a Memmodel that holds the default graph.
        *
        * @var          resource Memmodel
        * @access       private
        */
        var $defaultGraph;


        /**
        * Name of the DatasetMem.
        *
        * @var          string
        * @access       private
        */
        var $setName;

        /**
        * List of all NamedGraphs.
        *
        * @var          array
        * @access       private
        */
        var $graphs=array();

        /**
    * Constructor.
    * You can supply a Dataset name.
    *
    * @param string
        * @access       public
    */
        function DatasetMem($datasetName = null)
        {
                $this->setDatasetName($datasetName);
                $this->defaultGraph=new MemModel();
        }

//      === Graph level methods ========================

        /**
    * Sets the Datasets name.
    *
    * @param  string
        * @access       public
    */
        function setDatasetName($datasetName)
        {
                $this->setName=$datasetName;
        }

        /**
    * Returns the Datasets name.
    *
    * @return string
        * @access       public
    */
        function getDatasetName()
        {
                return $this->setName;
        }

        /**
         * Adds a NamedGraph to the set. Will replace a NamedGraph with the same name that is already in the set.
         *
         * @param NamedGraphMem
         */
        function addNamedGraph(&$graph)
        {
                $graphNameURI=$graph->getGraphName();
                $this->graphs[$graphNameURI]=&$graph;
        }

        /**
         * Overwrites the existting default graph.
         *
         * @param MemModel
         */
        function setDefaultGraph(&$graph)
        {
                $this->defaultGraph=&$graph;
        }

        /**
         * Returns a reference to the defaultGraph
         * @return Model
        */
        function &getDefaultGraph()
        {
                return $this->defaultGraph;
        }

        /**
         * Returns true, if an defaultGraph exists. False otherwise     .
         *
         * @return boolean
        */
        function hasDefaultGraph()
        {
                return $this->defaultGraph != null;
        }

        /**
         * Removes a NamedGraph from the set. Nothing happens
         * if no graph with that name is contained in the set.
         *
         * @param string
         */
        function removeNamedGraph($graphName)
        {
                unset($this->graphs[$graphName]);
        }

        /**
         * Tells wether the Dataset contains a NamedGraph.
         *
         * @param  string
         * @return boolean
         */
        function containsNamedGraph($graphName)
        {
                return isset($this->graphs[$graphName]) === true;
        }

        /**
         * Returns the NamedGraph with a specific name from the Dataset.
         * Changes to the graph will be reflected in the set.
         *
         * @param string
         * @return NamedGraphMem or NULL
         */
        function &getNamedGraph($graphName)
        {
                if (!isset($this->graphs[$graphName])) return NULL;
                return $this->graphs[$graphName];
        }

        /**
         * Returns the names of the namedGraphs in this set as strings in an array.
         *
         * @return Array
         */
        function listGraphNames()
        {
                return array_keys($this->graphs);
        }

        /**
         * Creates a new NamedGraph and adds it to the set. An existing
         * graph with the same name will be replaced.The name of the NamedGraph to be created ; must be an URI
         *
         * @param  string
         * @param  string
         * @return NamedGraphMem
         */
        function &createGraph($graphName,$baseURI = null)
        {
                $this->graphs[$graphName]=new NamedGraphMem($graphName,$baseURI);
                return $this->getNamedGraph($graphName);
        }

        /**
         * Deletes all NamedGraphs from the set.
         */
        function clear()
        {
                $this->graphs = array();
        }

        /**
         * Returns the number of NamedGraphs in the set. Empty graphs
         * are counted.
         *
         * @return int
         */
        function countGraphs()
        {
                return count($this->graphs);
        }

        /**
         * Returns the NamedGraph with a specific offset in the dataset.
         * Changes to the graph will be reflected in the set.
         *
         * @param int
         * @return NamedGraphMem or null
         * @access      private
         */
        function &getGraphWithOffset($offset)
        {
                $i=0;
                foreach ($this->graphs as $graph)
                {
                        if (($i++)==$offset)
                                return $graph;
                }
                $n = null;
                return $n;
        }

        /**
         * Returns an iterator over all {@link NamedGraph}s in the set.
         *
         * @return IteratorAllGraphsMem
         */
        function &listNamedGraphs()
        {
        require_once RDFAPI_INCLUDE_DIR . 'dataset/IteratorAllGraphsMem.php';
        $m = new IteratorAllGraphsMem($this);
        return $m;
        }

        /**
         * Tells wether the set contains any NamedGraphs.
         *
         * @return boolean
         */
        function isEmpty()
        {
                return $this->countGraphs() == 0;
        }

        /**
         * Adds all named graphs of the other dataset to this dataset.
         *
         * @param Dataset
         */
        function addAll($otherDataset)
        {
                for($iterator = $otherDataset->listNamedGraphs(); $iterator->valid(); $iterator->next())
                {
                        $current=$iterator->current();
                        $this->graphs[$current->getGraphName()]=$current;
                }

                if ($otherDataset->hasDefaultGraph())
                {
                        $this->defaultGraph = $this->defaultGraph->unite($otherDataset->getDefaultGraph());
                }
        }

//      === Quad level methods ========================

        /**
         * Adds a quad to the Dataset. The argument must not contain any
         * wildcards. If the quad is already present, nothing happens. A new
         * named graph will automatically be created if necessary.
         *
         * @param Quad
         */
        function addQuad(&$quad)
        {
                $graphName=$quad->getGraphName();
                if ($this->containsNamedGraph($graphName->getLabel())===false)
                        $this->createGraph($graphName->getLabel());

                $this->graphs[$graphName->getLabel()]->add($quad->getStatement());
        }


        /**
         * Tells wether the Dataset contains a quad or
         * quads matching a pattern.
         *
         * @param Resource $graphName
         * @param Resource $subject
         * @param Resource $predicate
         * @param Resource $object
         * @return boolean
         */
        function containsQuad($graphName,$subject,$predicate,$object)
        {
                if($graphName!=null)
                {
                        if ($this->containsNamedGraph($graphName->getLabel())!==true)
                                return false;

                        return ($this->graphs[$graphName->getLabel()]->findFirstMatchingStatement($subject,$predicate,$object)!=null);
                }

                foreach ($this->graphs as $graph)
                {
                        if ($graph->findFirstMatchingStatement($subject,$predicate,$object)!=null)
                                return true;
                };

                return false;
        }

        /**
         * Deletes a Quad from the RDF dataset.
         *
         * @param Quad
         */
        function removeQuad($quad)
        {
                        $graphName=$quad->getGraphName();

                        if($graphName!=null)
                        {
                                if ($this->containsNamedGraph($graphName->getLabel())!==true)
                                        return;

                                return ($this->graphs[$graphName->getLabel()]->remove($quad->getStatement())!=null);

                        }
                        foreach ($this->graphs as $graph)
                        {
                                $graph->remove($quad->getStatement());
                        };
        }

        /**
         * Counts the Quads in the RDF dataset. Identical Triples in
         * different NamedGraphs are counted individually.
         *
         * @return int
         */
        function countQuads()
        {
                $count=0;
                foreach ($this->graphs as $graph)
                {
                        $count+=$graph->size();
                }
                return $count;
        }

        /**
         * Finds Statements that match a quad pattern. The argument may contain
         * wildcards.
         *
         * @param Resource or Null
         * @param Resourceor Null
         * @param Resource or Null
         * @param Resource or Null
         * @return Iterator
         */
        function &findInNamedGraphs($graph,$subject,$predicate,$object,$returnAsTriples = false)
        {

                if ($graph!=null)
                {
                        $findGraph=&$this->getNamedGraph($graph->getLabel());
                        if($findGraph==null)
                                $findGraph=new MemModel();

                        return $findGraph->iterFind($subject,$predicate,$object);
                }


        require_once RDFAPI_INCLUDE_DIR . 'dataset/IteratorFindQuadsMem.php';
        $m = new IteratorFindQuadsMem($subject,$predicate,$object,$this->listNamedGraphs(),$returnAsTriples);
        return $m;
        }

        /**
         * Finds Statements that match a pattern in the default Graph. The argument may contain
         * wildcards.
         *
         * @param Resource or Null
         * @param Resource or Null
         * @param Resource or Null
         * @return Iterator
         */
        function &findInDefaultGraph($subject,$predicate,$object)
        {
                return $this->defaultGraph->iterFind($subject,$predicate,$object);
        }
}
?>