Location: PHPKode > scripts > PHP Universal Feed Generator > FeedWriter.php
<?php
// RSS 0.90  Officially obsoleted by 1.0
// RSS 0.91, 0.92, 0.93 and 0.94  Officially obsoleted by 2.0
// So, define constants for RSS 1.0, RSS 2.0 and ATOM 	

	define('RSS1', 'RSS 1.0', true);
	define('RSS2', 'RSS 2.0', true);
	define('ATOM', 'ATOM', true);

 /**
 * Univarsel Feed Writer class
 *
 * Genarate RSS 1.0, RSS2.0 and ATOM Feed
 *                             
 * @package     UnivarselFeedWriter
 * @author      Anis uddin Ahmad <hide@address.com>
 * @link        http://www.ajaxray.com/projects/rss
 */
 class FeedWriter
 {
	 private $channels      = array();  // Collection of channel elements
	 private $items         = array();  // Collection of items as object of FeedItem class.
	 private $data          = array();  // Store some other version wise data
	 private $CDATAEncoding = array();  // The tag names which have to encoded as CDATA
	 
	 private $version   = null; 
	
	/**
	* Constructor
	* 
	* @param    constant    the version constant (RSS1/RSS2/ATOM).       
	*/ 
	function __construct($version = RSS2)
	{	
		$this->version = $version;
			
		// Setting default value for assential channel elements
		$this->channels['title']        = $version . ' Feed';
		$this->channels['link']         = 'http://www.ajaxray.com/blog';
				
		//Tag names to encode in CDATA
		$this->CDATAEncoding = array('description', 'content:encoded', 'summary');
	}

	// Start # public functions ---------------------------------------------
	
	/**
	* Set a channel element
	* @access   public
	* @param    srting  name of the channel tag
	* @param    string  content of the channel tag
	* @return   void
	*/
	public function setChannelElement($elementName, $content)
	{
		$this->channels[$elementName] = $content ;
	}
	
	/**
	* Set multiple channel elements from an array. Array elements 
	* should be 'channelName' => 'channelContent' format.
	* 
	* @access   public
	* @param    array   array of channels
	* @return   void
	*/
	public function setChannelElementsFromArray($elementArray)
	{
		if(! is_array($elementArray)) return;
		foreach ($elementArray as $elementName => $content) 
		{
			$this->setChannelElement($elementName, $content);
		}
	}
	
	/**
	* Genarate the actual RSS/ATOM file
	* 
	* @access   public
	* @return   void
	*/ 
	public function genarateFeed()
	{
		header("Content-type: text/xml");
		
		$this->printHead();
		$this->printChannels();
		$this->printItems();
		$this->printTale();
	}
	
	/**
	* Create a new FeedItem.
	* 
	* @access   public
	* @return   object  instance of FeedItem class
	*/
	public function createNewItem()
	{
		$Item = new FeedItem($this->version);
		return $Item;
	}
	
	/**
	* Add a FeedItem to the main class
	* 
	* @access   public
	* @param    object  instance of FeedItem class
	* @return   void
	*/
	public function addItem($feedItem)
	{
		$this->items[] = $feedItem;    
	}
	
	
	// Wrapper functions -------------------------------------------------------------------
	
	/**
	* Set the 'title' channel element
	* 
	* @access   public
	* @param    srting  value of 'title' channel tag
	* @return   void
	*/
	public function setTitle($title)
	{
		$this->setChannelElement('title', $title);
	}
	
	/**
	* Set the 'description' channel element
	* 
	* @access   public
	* @param    srting  value of 'description' channel tag
	* @return   void
	*/
	public function setDescription($desciption)
	{
		$this->setChannelElement('description', $desciption);
	}
	
	/**
	* Set the 'link' channel element
	* 
	* @access   public
	* @param    srting  value of 'link' channel tag
	* @return   void
	*/
	public function setLink($link)
	{
		$this->setChannelElement('link', $link);
	}
	
	/**
	* Set the 'image' channel element
	* 
	* @access   public
	* @param    srting  title of image
	* @param    srting  link url of the imahe
	* @param    srting  path url of the image
	* @return   void
	*/
	public function setImage($title, $link, $url)
	{
		$this->setChannelElement('image', array('title'=>$title, 'link'=>$link, 'url'=>$url));
	}
	
	/**
	* Set the 'about' channel element. Only for RSS 1.0
	* 
	* @access   public
	* @param    srting  value of 'about' channel tag
	* @return   void
	*/
	public function setChannelAbout($url)
	{
		$this->data['ChannelAbout'] = $url;    
	}
	
  /**
  * Genarates an UUID
  * @author     Anis uddin Ahmad <hide@address.com>
  * @param      string  an optional prefix
  * @return     string  the formated uuid
  */
  public function uuid($key = null, $prefix = '') 
  {
	$key = ($key == null)? uniqid(rand()) : $key;
	$chars = md5($key);
	$uuid  = substr($chars,0,8) . '-';
	$uuid .= substr($chars,8,4) . '-';
	$uuid .= substr($chars,12,4) . '-';
	$uuid .= substr($chars,16,4) . '-';
	$uuid .= substr($chars,20,12);

	return $prefix . $uuid;
  }
	// End # public functions ----------------------------------------------
	
	// Start # private functions ----------------------------------------------
	
	/**
	* Prints the xml and rss namespace
	* 
	* @access   private
	* @return   void
	*/
	private function printHead()
	{
		$out  = '<?xml version="1.0" encoding="utf-8"?>' . "\n";
		
		if($this->version == RSS2)
		{
			$out .= '<rss version="2.0"
					xmlns:content="http://purl.org/rss/1.0/modules/content/"
					xmlns:wfw="http://wellformedweb.org/CommentAPI/"
				  >' . PHP_EOL;
		}    
		elseif($this->version == RSS1)
		{
			$out .= '<rdf:RDF 
					 xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
					 xmlns="http://purl.org/rss/1.0/"
					 xmlns:dc="http://purl.org/dc/elements/1.1/"
					>' . PHP_EOL;;
		}
		else if($this->version == ATOM)
		{
			$out .= '<feed xmlns="http://www.w3.org/2005/Atom">' . PHP_EOL;;
		}
		echo $out;
	}
	
	/**
	* Closes the open tags at the end of file
	* 
	* @access   private
	* @return   void
	*/
	private function printTale()
	{
		if($this->version == RSS2)
		{
			echo '</channel>' . PHP_EOL . '</rss>'; 
		}    
		elseif($this->version == RSS1)
		{
			echo '</rdf:RDF>';
		}
		else if($this->version == ATOM)
		{
			echo '</feed>';
		}
	  
	}

	/**
	* Creates a single node as xml format
	* 
	* @access   private
	* @param    srting  name of the tag
	* @param    mixed   tag value as string or array of nested tags in 'tagName' => 'tagValue' format
	* @param    array   Attributes(if any) in 'attrName' => 'attrValue' format
	* @return   string  formatted xml tag
	*/
	private function makeNode($tagName, $tagContent, $attributes = null)
	{        
		$nodeText = '';
		$attrText = '';

		if(is_array($attributes))
		{
			foreach ($attributes as $key => $value) 
			{
				$attrText .= " $key=\"$value\" ";
			}
		}
		
		if(is_array($tagContent) && $this->version == RSS1)
		{
			$attrText = ' rdf:parseType="Resource"';
		}
		
		
		$attrText .= (in_array($tagName, $this->CDATAEncoding) && $this->version == ATOM)? ' type="html" ' : '';
		$nodeText .= (in_array($tagName, $this->CDATAEncoding))? "<{$tagName}{$attrText}><![CDATA[" : "<{$tagName}{$attrText}>";
		 
		if(is_array($tagContent))
		{ 
			foreach ($tagContent as $key => $value) 
			{
				$nodeText .= $this->makeNode($key, $value);
			}
		}
		else
		{
			$nodeText .= (in_array($tagName, $this->CDATAEncoding))? $tagContent : htmlentities($tagContent);
		}           
			
		$nodeText .= (in_array($tagName, $this->CDATAEncoding))? "]]></$tagName>" : "</$tagName>";

		return $nodeText . PHP_EOL;
	}
	
	/**
	* @desc     Print channels
	* @access   private
	* @return   void
	*/
	private function printChannels()
	{
		//Start channel tag
		switch ($this->version) 
		{
		   case RSS2: 
				echo '<channel>' . PHP_EOL;        
				break;
		   case RSS1: 
				echo (isset($this->data['ChannelAbout']))? "<channel rdf:about=\"{$this->data['ChannelAbout']}\">" : "<channel rdf:about=\"{$this->channels['link']}\">";
				break;
		}
		
		//Print Items of channel
		foreach ($this->channels as $key => $value) 
		{
			if($this->version == ATOM && $key == 'link') 
			{
				// ATOM prints link element as href attribute
				echo $this->makeNode($key,'',array('href'=>$value));
				//Add the id for ATOM
				echo $this->makeNode('id',$this->uuid($value,'urn:uuid:'));
			}
			else
			{
				echo $this->makeNode($key, $value);
			}    
			
		}
		
		//RSS 1.0 have special tag <rdf:Seq> with channel 
		if($this->version == RSS1)
		{
			echo "<items>" . PHP_EOL . "<rdf:Seq>" . PHP_EOL;
			foreach ($this->items as $item) 
			{
				$thisItems = $item->getElements();
				echo "<rdf:li resource=\"{$thisItems['link']['content']}\"/>" . PHP_EOL;
			}
			echo "</rdf:Seq>" . PHP_EOL . "</items>" . PHP_EOL . "</channel>" . PHP_EOL;
		}
	}
	
	/**
	* Prints formatted feed items
	* 
	* @access   private
	* @return   void
	*/
	private function printItems()
	{    
		foreach ($this->items as $item) 
		{
			$thisItems = $item->getElements();
			
			//the argument is printed as rdf:about attribute of item in rss 1.0 
			echo $this->startItem($thisItems['link']['content']);
			
			foreach ($thisItems as $feedItem ) 
			{
				echo $this->makeNode($feedItem['name'], $feedItem['content'], $feedItem['attributes']); 
			}
			echo $this->endItem();
		}
	}
	
	/**
	* Make the starting tag of channels
	* 
	* @access   private
	* @param    srting  The vale of about tag which is used for only RSS 1.0
	* @return   void
	*/
	private function startItem($about = false)
	{
		if($this->version == RSS2)
		{
			echo '<item>' . PHP_EOL; 
		}    
		elseif($this->version == RSS1)
		{
			if($about)
			{
				echo "<item rdf:about=\"$about\">" . PHP_EOL;
			}
			else
			{
				die('link element is not set .\n It\'s required for RSS 1.0 to be used as about attribute of item');
			}
		}
		else if($this->version == ATOM)
		{
			echo "<entry>" . PHP_EOL;
		}    
	}
	
	/**
	* Closes feed item tag
	* 
	* @access   private
	* @return   void
	*/
	private function endItem()
	{
		if($this->version == RSS2 || $this->version == RSS1)
		{
			echo '</item>' . PHP_EOL; 
		}    
		else if($this->version == ATOM)
		{
			echo "</entry>" . PHP_EOL;
		}
	}
	

	
	// End # private functions ----------------------------------------------
	
 } // end of class FeedWriter
 
// autoload classes
function __autoload($class_name) 
{
	require_once $class_name . '.php';
}
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