source: Dev/trunk/rdfapi/resModel/ResContainer.php @ 12

<?php
// ----------------------------------------------------------------------------------
// Class: ResContainer
// ----------------------------------------------------------------------------------

/**
* An RDF Container.
* This Class defines methods for accessing RDF container resources. 
* These methods operate on the RDF statements contained in a model. 
*
* @version  $Id: ResContainer.php 320 2006-11-21 09:38:51Z tgauss $
* @author Daniel Westphal <mail at d-westphal dot de>
*
* @package      resModel
* @access       public
**/

class ResContainer extends ResResource 
{
        /**
        * Holds a ResResource of this container type rdf:Seq, rdf:Alt, or rdf:Bag
        * @var          ResResource
        * @access       private
        */
        var $containerType;
        
        
        /**
    * Constructor
        * You can supply a URI
    *
    * @param string $uri 
        * @access       public
    */  
        function ResContainer($uri = null)
        {
                parent::ResResource($uri);
        }       
        
        /**
        * Add a new value to a container.
        * The new value is added as the last element of the container.
        *
        * @param        object ResResource/ResLiteral   $object
        * @access       public
        */
        function add($object)
        {
                //type this container, if it isn't already typed
                if(!$this->hasProperty(new ResResource(RDF_NAMESPACE_URI.RDF_TYPE)))
                        $this->addProperty(new ResResource(RDF_NAMESPACE_URI.RDF_TYPE),$this->containerType);
                //get the current size
                $actualSize=$this->size();
                //add the object to the last position
                $this->addProperty(new ResResource(RDF_NAMESPACE_URI.'_'.($actualSize+1)),$object);
        }
        
        /**
        * Determine whether the container contains a value
        *
        * @param        obejct ResResource/ResLiteral   $resResource
        * @return       boolean 
        * @access       public
        */
        function contains($resResource)
        {
                //get all container's properties 
                foreach ($this->listProperties() as $statement)
                {
                        //if the property matches a container membership property
                        if ($this->_predicateLabelMatchesMembershipProperty($statement->getLabelPredicate()))
                        {
                                //check, if it's the value, we're looking for. 
                                if ($resResource->equals($statement->getObject()))
                                        return true;
                        }       
                }
                return false;
        }
        
        /**
        * Returns true, if this resource is a container from type rdf:Alt
        *
        * @return       boolean 
        * @access       public
        */      
        function isAlt()
        {
                return ($this->containerType->getURI()==RDF_NAMESPACE_URI.RDF_ALT);
        }
        
        /**
        * Returns true, if this resource is a container from type rdf:Bag
        *
        * @return       boolean 
        * @access       public
        */      
        function isBag()
        {
                return ($this->containerType->getURI()==RDF_NAMESPACE_URI.RDF_BAG);
        }

        /**
        * Returns true, if this resource is a container from type rdf:Seq
        *
        * @return       boolean 
        * @access       public
        */      
        function isSeq()
        {
                return ($this->containerType->getURI()==RDF_NAMESPACE_URI.RDF_SEQ);
        }
        
        /**
        * Get an array of all resources that are values of this container
        *
        * @return       array 
        * @access       public
        */      
        function getMembers()
        {
                $return=array();
                foreach ($this->listProperties() as $statement)
                {
                        $predicateLabel=$statement->getLabelPredicate();
                        if ($this->_predicateLabelMatchesMembershipProperty($predicateLabel))
                        {
                                $return[$this->_getMemberIndexNrFromMembershipPropertyLabel($predicateLabel)] = $statement->getObject();
                        }       
                }
                return $return;
        }
        
        /**
        * Remove a value from the container.
        * 
        * Once removed, the values in the container with a higher ordinal value are renumbered. 
        * The renumbering algorithm depends on the type of container.
        *
        * @param        obejct ResResource/ResLiteral   $resResource
        * @access       public
        */
        function remove($object)
        {
                $deleteFromIndex=array();
                //get all container members
                $memberIndex=$this->getMembers();
                
                //check each container member if it equals the resoure to be removed
                foreach ($memberIndex as $key => $value)
                {
                        //save the statements positio in the container
                        if($object->equals($value))
                                        $deleteFromIndex[]=$key;        
                }

                //delete all found container members
                foreach ($deleteFromIndex as $index)
                {
                        $this->removeAll($this->_getMembershipPropertyWithIndex($index));

                        //renumber all members with higher ordinal numbers than the deleted one
                        for ($i = $index;$i < count($memberIndex); $i++)
                        {
                                $this->removeAll($this->_getMembershipPropertyWithIndex($i+1));
                                $this->addProperty($this->_getMembershipPropertyWithIndex($i),$memberIndex[$i+1]);
                        }               
                }
                
        }
        
        /**
        * Returns the number values in the container.
        *
        * @return       integer 
        * @access       public
        */      
        function size()
        {
                return count($this->getMembers());
        }
        
        /**
        * Checks, if a predicate label fits a container membership property rdf:_n
        *
        * @param        string  $predicateLabel
        * @return       boolean 
        * @access       private
        */
        function _predicateLabelMatchesMembershipProperty($predicateLabel)
        {
                return substr($predicateLabel,0,strlen(RDF_NAMESPACE_URI.'_')) == RDF_NAMESPACE_URI.'_';
        }
        
        /**
        * Get the ordinal number from a membership property rdf:_n
        *
        * @param        string  $predicateLabel
        * @return       integer 
        * @access       private
        */
        function _getMemberIndexNrFromMembershipPropertyLabel($predicateLabel)
        {
                return (int)substr($predicateLabel,strlen(RDF_NAMESPACE_URI.'_'));
        }
        
        /**
        * Get a membership property rdf:_n with index $int 
        *
        * @param        intger  $int
        * @return       string 
        * @access       private
        */
        function _getMembershipPropertyWithIndex($int)
        {
                return new ResResource(RDF_NAMESPACE_URI.'_'.$int);     
        }
}
?>