source: Dev/trunk/rdfapi/util/StatementIterator.php @ 12

<?php

// ----------------------------------------------------------------------------------
// Class: StatementIterator
// ----------------------------------------------------------------------------------

/**
 * Iterator for traversing models. 
 * This class can be used for iterating forward and backward trough MemModels.
 * It should be instanced using the getIterator() method of a MemModel.
 * 
 * @version  $Id: StatementIterator.php 268 2006-05-15 05:28:09Z tgauss $
 * @author Daniel Westphal <mail at d-westphal dot de>
 * @author Chris Bizer <chris@bizer.de>
 *
 * @package utility
 * @access      public
 *
 */ 
 class StatementIterator extends Object {

        /**
        * Reference to the MemModel
        * @var          object MemModel
        * @access       private
        */      
    var $model;

        /**
        * Current position
        * StatementIterator does not use the build in PHP array iterator,
        * so you can use serveral iterators on a single MemModel.
        * @var          integer
        * @access       private
        */      
    var $position;
   
  
   /**
    * Constructor
    *
    * @param    object  MemModel
        * @access       public
    */
    function StatementIterator(&$model) {
                $this->model = $model;
                reset($this->model->triples);
                $this->position = -1;
        }
 
  /**
   * Returns TRUE if there are more statements.
   * @return    boolean
   * @access    public  
   */
  function hasNext() {
                if ($this->position == -1)
                { 
                        if(current($this->model->triples)!=NULL)
                        {
                                return TRUE;    
                        } else 
                        {
                                return FALSE;
                        }
                };

                if (next($this->model->triples)!=NULL ) 
                {       
                        prev($this->model->triples);            
                        return TRUE;
                } else 
                {
                        end($this->model->triples);
                        return FALSE;
                };
   }

  /**
   * Returns TRUE if the first statement has not been reached.
   * @return    boolean
   * @access    public  
   */
  function hasPrevious() {
                if (prev($this->model->triples)!=NULL) 
                {
                        next($this->model->triples);
                        return TRUE;
                } else {
                        reset($this->model->triples);
                        return FALSE;
                };
  }     
   
  /**
   * Returns the next statement.
   * @return    statement or NULL if there is no next statement.
   * @access    public  
   */
  function next() {
                if ($this->position == -1)
                { 
                        if($return=current($this->model->triples))
                        {
                                $this->position=key($this->model->triples);
                                return $return; 
                        } else 
                        {
                                $this->position=key($this->model->triples);
                                return NULL;
                        };
                };
                
                
                if ($return=next($this->model->triples)) {
                        $this->position=key($this->model->triples);
                        return $return;
                } else {
                        $this->position=key($this->model->triples);
                        return NULL;
                };
   }

  /**
   * Returns the previous statement.
   * @return    statement or NULL if there is no previous statement.
   * @access    public  
   */
  function previous() {
                if ($return=prev($this->model->triples)) {
                        $this->position=key($this->model->triples);
                        return $return;
                } else {
                        $this->position=key($this->model->triples);
                        return NULL;
                }   
  }

  /**
   * Returns the current statement.
   * @return    statement or NULL if there is no current statement.
   * @access    public  
   */
  function current() {
                if ($this->position==-1) return NULL;
        
                if ($return=current($this->model->triples)) {
                        return $return;
                } else {
                        return NULL;
                }
   }
   
  /**
   * Moves the pointer to the first statement.
   * @return    void
   * @access    public  
   */
  function moveFirst() {
                        reset($this->model->triples);
                        $this->position=0;
   }

  /**
   * Moves the pointer to the last statement.
   * @return    void
   * @access    public  
   */
  function moveLast() {
                        end($this->model->triples);
                        $this->position=key($this->model->triples);
   }
   
     /**
   * Moves the pointer to a specific statement.
   * If you set an off-bounds value, the position will be set to the last element
   * @param     integer
   * @return    void
   * @access    public  
   */
  function moveTo($position) {
        
                        if ($position + 1 > count($this->model->triples))
                        {
                                end($this->model->triples);
                        } else 
                        {
                                reset($this->model->triples);
                                
                                for ($i = 1; $i < $position; $i++) {
                                   next($this->model->triples);
                                }
                        };
                        $this->position=key($this->model->triples);
   }
   
     /**
   * Returns the current position of the iterator.
   * @return    integer
   * @access    public  
   */
  function getCurrentPosition() {
                        return key($this->model->triples);
   }
  
} 

?>