path: root/engine/lib/opendd.php

<?php
	/**
	 * OpenDD PHP Library.
	 * 
	 * @package Elgg
	 * @subpackage Core
	 * @license http://www.gnu.org/licenses/old-licenses/gpl-2.0.html GNU Public License version 2
	 * @author Marcus Povey
	 * @version 0.1
	 * @copyright Curverider Ltd 2008
	 * @link http://elgg.org/
	 */
	
	include_once("xml.php");
	
	/**
	 * @class ODDDocument ODD Document container.
	 * This class is used during import and export to construct.
	 * @author Marcus Povey
	 */
	class ODDDocument implements Iterator
	{
		/**
		 * ODD Version
		 *
		 * @var string
		 */
		private $ODDSupportedVersion = "1.0"; 
		
		/**
		 * Elements of the document.
		 */
		private $elements;
		
		public function __construct(array $elements = NULL)
		{
			if ($elements)
				$this->elements = $elements;
			else
				$this->elements = array();
		}
		
		/**
		 * Return the version of ODD being used.
		 *
		 * @return string
		 */
		public function getVersion() { return $this->ODDSupportedVersion; }
		
		public function addElement(ODD $element) { $this->elements[] = $element; }
		public function addElements(array $elements)
		{
			foreach ($elements as $element)
				$this->addElement($element);
		}
		
		public function getElements() { return $this->elements; }
		
		/**
		 * Magic function to generate valid ODD XML for this item.
		 */
		public function __toString()
		{
			$xml = "";
			
			// Output begin tag
			$generated = date("r");
			$xml .= "<odd version=\"{$this->ODDSupportedVersion}\" generated=\"$generated\">\n";

			// Get XML for elements
			foreach ($this->elements as $element)
				$xml .= "$element";
			
			// Output end tag
			$xml .= "</odd>\n";	
			
			return $xml;
		}
		
		// ITERATOR INTERFACE //////////////////////////////////////////////////////////////
		/*
		 * This lets an entity's attributes be displayed using foreach as a normal array.
		 * Example: http://www.sitepoint.com/print/php5-standard-library
		 */
		
		private $valid = FALSE; 
		
   		function rewind() 
   		{ 
   			$this->valid = (FALSE !== reset($this->elements));  
   		}
   
   		function current() 
   		{ 
   			return current($this->elements); 
   		}
		
   		function key() 
   		{ 
   			return key($this->elements); 
   		}
		
   		function next() 
   		{
   			$this->valid = (FALSE !== next($this->elements));  
   		}
   		
   		function valid() 
   		{ 
   			return $this->valid;  
   		}
	}
		
	/**
	 * Open Data Definition (ODD) superclass.
	 * @package Elgg
	 * @subpackage Core
	 * @author Marcus Povey
	 */
	abstract class ODD
	{		
		/**
		 * Attributes.
		 */
		private $attributes = array();
		
		/**
		 * Optional body.
		 */
		private $body;
		
		/**
		 * Construct an ODD document with initial values.
		 */
		public function __construct()
		{
			$this->body = "";
		}
		
		public function setAttribute($key, $value) { $this->attributes[$key] = $value; }
		public function getAttribute($key) 
		{ 
			if (isset($this->attributes[$key]))
				return $this->attributes[$key];
				
			return NULL;
		}
		public function setBody($value) { $this->body = $value; }
		public function getBody() { return $this->body; }
		
		/**
		 * For serialisation, implement to return a string name of the tag eg "header" or "metadata".
		 * @return string
		 */
		abstract protected function getTagName();

		/**
		 * Magic function to generate valid ODD XML for this item.
		 */
		public function __toString()
		{
			// Construct attributes
			$attr = "";
			foreach ($this->attributes as $k => $v)
				$attr .= ($v!="") ? "$k=\"$v\" " : "";
			
			$body = $this->getBody();
			$tag = $this->getTagName();
			
			$end = "/>";
			if ($body!="")
				$end = ">$body</{$tag}>";
			
			return "<{$tag} $attr" . $end . "\n";  
		}
	}
	
	/**
	 * ODD Entity class.
	 * @package Elgg
	 * @subpackage Core
	 * @author Marcus Povey
	 */
	class ODDEntity extends ODD
	{
		function __construct($uuid, $class, $subclass = "")
		{
			parent::__construct();
			
			$this->setAttribute('uuid', $uuid);
			$this->setAttribute('class', $class);
			$this->setAttribute('subclass', $subclass);	
		}
		
		protected function getTagName() { return "entity"; }
	}
	
	/**
	 * ODD Metadata class.
	 * @package Elgg
	 * @subpackage Core
	 * @author Marcus Povey
	 */
	class ODDMetaData extends ODD
	{
		function __construct($uuid, $entity_uuid, $name, $value, $type = "", $owner_uuid = "")
		{
			parent::__construct();
			
			$this->setAttribute('uuid', $uuid);
			$this->setAttribute('entity_uuid', $entity_uuid);
			$this->setAttribute('name', $name);
			$this->setAttribute('type', $type);	
			$this->setAttribute('owner_uuid', $owner_uuid);
			$this->setBody($value);
		}
		
		protected function getTagName() { return "metadata"; }
	}
	
	/**
	 * ODD Relationship class.
	 * @package Elgg
	 * @subpackage Core
	 * @author Marcus Povey
	 */
	class ODDRelationship extends ODD
	{
		function __construct($uuid1, $type, $uuid2)
		{
			parent::__construct();
			
			$this->setAttribute('uuid1', $uuid1);
			$this->setAttribute('type', $type);
			$this->setAttribute('uuid2', $uuid2);
		}
		
		protected function getTagName() { return "relationship"; }
	}
	
	/**
	 * Attempt to construct an ODD object out of a XmlElement or sub-elements.
	 * 
	 * @param XmlElement $element The element(s)
	 * @return mixed An ODD object if the element can be handled, or false.
	 */
	function ODD_factory(XmlElement $element)
	{
		$name = $element->name; 
		$odd = false;
		
		switch ($name)
		{
			case 'entity' : $odd = new ODDEntity("","",""); break;
			case 'metadata' : $odd = new ODDMetaData("","","",""); break;
			case 'relationship' : $odd = new ODDRelationship("","",""); break;
		}
		
		// Now populate values
		if ($odd)
		{
			// Attributes
			foreach ($element->attributes as $k => $v)
				$odd->setAttribute($k,$v);
				
			// Body
			$odd->setBody($element->content);
		}
		
		return $odd;
	}
	
	/**
	 * Import an ODD document.
	 * 
	 * @param string $xml The XML ODD.
	 * @return ODDDocument
	 */
	function ODD_Import($xml)
	{
		// Parse XML to an array
		$elements = xml_2_object($xml);

		// Create ODDDocument
		$document = new ODDDocument();
		
		// Itterate through array of elements and construct ODD document
		foreach ($elements->children as $child) 
		{
			$odd = ODD_factory($child);
			
			if ($odd) 
				$document->addElement($odd);
		}
		
		return $document;
	}
	
	/**
	 * Export an ODD Document.
	 *
	 * @param ODDDocument $document The Document.
	 */
	function ODD_Export(ODDDocument $document)
	{
		return "$document";
	}
	
?>