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<?php
/**
* @package Joomla.Libraries
* @subpackage Feed
*
* @copyright Copyright (C) 2005 - 2013 Open Source Matters, Inc. All rights reserved.
* @license GNU General Public License version 2 or later; see LICENSE
*/
defined('JPATH_BASE') or die;
/**
* Feed Parser class.
*
* @package Joomla.Libraries
* @subpackage Feed
* @since 3.0
*/
abstract class JFeedParser
{
/**
* @var string The feed element name for the entry elements.
* @since 3.0
*/
protected $entryElementName = 'entry';
/**
* @var array
* @since 3.0
*/
protected $namespaces = array();
/**
* @var XMLReader
* @since 3.0
*/
protected $stream;
/**
* @var DOMDocument
* @since 3.0
*/
private $_node;
/**
* Constructor.
*
* @param XMLReader $stream The XMLReader stream object for the feed.
*
* @since 3.0
*/
public function __construct(XMLReader $stream)
{
$this->_node = new DOMDocument;
$this->stream = $stream;
}
/**
* Method to parse the feed into a JFeed object.
*
* @return JFeed
*
* @since 3.0
*/
public function parse()
{
$feed = new JFeed;
// Detect the feed version.
$this->initialise();
// Let's get this party started...
do
{
// Expand the element for processing.
$el = $this->expandToSimpleXml();
// Get the list of namespaces used within this element.
$ns = $el->getNamespaces(true);
// Get an array of available namespace objects for the element.
$namespaces = array();
foreach ($ns as $prefix => $uri)
{
// Ignore the empty namespace prefix.
if (empty($prefix))
{
continue;
}
// Get the necessary namespace objects for the element.
$namespace = $this->fetchNamespace($prefix);
if ($namespace)
{
$namespaces[] = $namespace;
}
}
// Process the element.
$this->processElement($feed, $el, $namespaces);
// Skip over this element's children since it has been processed.
$this->moveToClosingElement();
}
while ($this->moveToNextElement());
return $feed;
}
/**
* Method to register a namespace handler object.
*
* @param string $prefix The XML namespace prefix for which to register the namespace object.
* @param JFeedParserNamespace $namespace The namespace object to register.
*
* @return JFeed
*
* @since 3.0
*/
public function registerNamespace($prefix, JFeedParserNamespace $namespace)
{
$this->namespaces[$prefix] = $namespace;
return $this;
}
/**
* Method to initialise the feed for parsing. If child parsers need to detect versions or other
* such things this is where you'll want to implement that logic.
*
* @return void
*
* @since 3.0
*/
abstract protected function initialise();
/**
* Method to parse a specific feed element.
*
* @param JFeed $feed The JFeed object being built from the parsed feed.
* @param SimpleXMLElement $el The current XML element object to handle.
* @param array $namespaces The array of relevant namespace objects to process for the element.
*
* @return void
*
* @since 3.0
*/
protected function processElement(JFeed $feed, SimpleXMLElement $el, array $namespaces)
{
// Build the internal method name.
$method = 'handle' . ucfirst($el->getName());
// If we are dealing with an item then it is feed entry time.
if ($el->getName() == $this->entryElementName)
{
// Create a new feed entry for the item.
$entry = new JFeedEntry;
// First call the internal method.
$this->processFeedEntry($entry, $el);
foreach ($namespaces as $namespace)
{
if ($namespace instanceof JFeedParserNamespace)
{
$namespace->processElementForFeedEntry($entry, $el);
}
}
// Add the new entry to the feed.
$feed->addEntry($entry);
}
// Otherwise we treat it like any other element.
else
{
// First call the internal method.
if (is_callable(array($this, $method)))
{
$this->$method($feed, $el);
}
foreach ($namespaces as $namespace)
{
if ($namespace instanceof JFeedParserNamespace)
{
$namespace->processElementForFeed($feed, $el);
}
}
}
}
/**
* Method to expand the current reader node into a SimpleXML node for more detailed reading
* and manipulation.
*
* @return SimpleXMLElement
*
* @since 3.0
* @throws RuntimeException
*/
protected function expandToSimpleXml()
{
// Whizbang! And now we have a SimpleXMLElement element from the current stream node. **MAGIC** :-)
$el = simplexml_import_dom($this->_node->importNode($this->stream->expand(), true), 'SimpleXMLElement');
// Let's take care of some sanity checking.
if (!($el instanceof SimpleXMLElement))
{
// @codeCoverageIgnoreStart
throw new RuntimeException('Unable to expand node to SimpleXML element.');
// @codeCoverageIgnoreEnd
}
return $el;
}
/**
* Method to get a namespace object for a given namespace prefix.
*
* @param string $prefix The XML prefix for which to fetch the namespace object.
*
* @return mixed JFeedParserNamespace or false if none exists.
*
* @since 3.0
*/
protected function fetchNamespace($prefix)
{
if (isset($this->namespaces[$prefix]))
{
return $this->namespaces[$prefix];
}
$className = get_class($this) . ucfirst($prefix);
if (class_exists($className))
{
$this->namespaces[$prefix] = new $className;
return $this->namespaces[$prefix];
}
return false;
}
/**
* Method to move the stream parser to the next XML element node.
*
* @param string $name The name of the element for which to move the stream forward until is found.
*
* @return boolean True if the stream parser is on an XML element node.
*
* @since 3.0
*/
protected function moveToNextElement($name = null)
{
// Only keep looking until the end of the stream.
while ($this->stream->read())
{
// As soon as we get to the next ELEMENT node we are done.
if ($this->stream->nodeType == XMLReader::ELEMENT)
{
// If we are looking for a specific name make sure we have it.
if (isset($name) && ($this->stream->name != $name))
{
continue;
}
return true;
}
}
return false;
}
/**
* Method to move the stream parser to the closing XML node of the current element.
*
* @return void
*
* @since 3.0
* @throws RuntimeException If the closing tag cannot be found.
*/
protected function moveToClosingElement()
{
// If we are on a self-closing tag then there is nothing to do.
if ($this->stream->isEmptyElement)
{
return;
}
// Get the name and depth for the current node so that we can match the closing node.
$name = $this->stream->name;
$depth = $this->stream->depth;
// Only keep looking until the end of the stream.
while ($this->stream->read())
{
// If we have an END_ELEMENT node with the same name and depth as the node we started with we have a bingo. :-)
if (($this->stream->name == $name) && ($this->stream->depth == $depth) && ($this->stream->nodeType == XMLReader::END_ELEMENT))
{
return;
}
}
// @codeCoverageIgnoreStart
throw new RuntimeException('Unable to find the closing XML node.');
// @codeCoverageIgnoreEnd
}
}