<?php

// ----------------------------------------------------------------------------------
// Class: Literal
// ----------------------------------------------------------------------------------

/**
 * An RDF literal.
 * The literal supports the xml:lang tag.
 * 
 * History:
 * 09-10-2002                : First version of this class.
 *
 * @version  V0.1
 * @author Chris Bizer <hide@address.com>
 *
 * @package model
 * @todo nothing
 * @access	public
 *
 */
 class Literal extends Node {

	/**
	* Label of the literal
	* @var		string
	* @access	private
	*/	
    var $label;
   /**
	* Language of the literal
	* @var		string
	* @access	private
	*/	
    var $lang; 

   /**
    * Constructor
    *
    * @param	string	$str			label of the literal
 	* @param	string	$language		optional language identifier 
    *
    */
	function Literal($str, $language = NULL) {
	
	    $this->label = $str;
    
		if ($language != NULL) {
			$this->lang = $language;
		} else {
			$this->lang = NULL;
		}
	}
  
  /**
   * Returns the string value of the literal.
   *
   * @access	public
   * @return	string value of the literal
   */
  function getLabel() {

    return $this->label;
  }

  /**
   * Returns the language of the literal.
   *
   * @access	public 
   * @return	string language of the literal
   */
  function getLanguage() {

    return $this->lang;
  }

  /**
   * Checks if ihe literal equals another literal.
   * Two literals are equal, if they have the same label and they
   * have the same language or both have no language property set. 
   *
   * @access	public 
   * @param		object	literal $that
   * @return	boolean 
   */  
  function equals ($that) {
    
	if (($that == NULL) or !(is_a($that, "Literal"))) {
	  return false;
    }

	if ($this->label == $that->getLabel() && ($this->language == $that->getLanguage() ||
	   ($this->language == NULL && $that->getLanguage() == NULL))) { 
		return true;
	}  

    return false;
  }

  /**
   * Dumps literal.
   *
   * @access	public 
   * @return	string 
   */  
  function toString() {
	$dump = "Literal(\"" . $this->label ."\"";
	if ($this->lang != NULL)
		$dump .= ", lang=\"" . $this->lang ."\"";
	$dump .= ")";    
    return $dump;
  }
  

} // end: Literal




?>