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<?php
/**
* @package Joomla.Administrator
* @subpackage com_finder
*
* @copyright Copyright (C) 2005 - 2013 Open Source Matters, Inc. All rights reserved.
* @license GNU General Public License version 2 or later; see LICENSE
*/
defined('_JEXEC') or die;
/**
* Parser base class for the Finder indexer package.
*
* @package Joomla.Administrator
* @subpackage com_finder
* @since 2.5
*/
abstract class FinderIndexerParser
{
/**
* Method to get a parser, creating it if necessary.
*
* @param string $format The type of parser to load.
*
* @return FinderIndexerParser A FinderIndexerParser instance.
*
* @since 2.5
* @throws Exception on invalid parser.
*/
public static function getInstance($format)
{
static $instances;
// Only create one parser for each format.
if (isset($instances[$format]))
{
return $instances[$format];
}
// Create an array of instances if necessary.
if (!is_array($instances))
{
$instances = array();
}
// Setup the adapter for the parser.
$format = JFilterInput::getInstance()->clean($format, 'cmd');
$path = dirname(__FILE__) . '/parser/' . $format . '.php';
$class = 'FinderIndexerParser' . ucfirst($format);
// Check if a parser exists for the format.
if (file_exists($path))
{
// Instantiate the parser.
include_once $path;
$instances[$format] = new $class;
}
else
{
// Throw invalid format exception.
throw new Exception(JText::sprintf('COM_FINDER_INDEXER_INVALID_PARSER', $format));
}
return $instances[$format];
}
/**
* Method to parse input and extract the plain text. Because this method is
* called from both inside and outside the indexer, it needs to be able to
* batch out its parsing functionality to deal with the inefficiencies of
* regular expressions. We will parse recursively in 2KB chunks.
*
* @param string $input The input to parse.
*
* @return string The plain text input.
*
* @since 2.5
*/
public function parse($input)
{
$return = null;
// Parse the input in batches if bigger than 2KB.
if (strlen($input) > 2048)
{
$start = 0;
$end = strlen($input);
$chunk = 2048;
while ($start < $end)
{
// Setup the string.
$string = substr($input, $start, $chunk);
// Find the last space character if we aren't at the end.
$ls = (($start + $chunk) < $end ? strrpos($string, ' ') : false);
// Truncate to the last space character.
if ($ls !== false)
{
$string = substr($string, 0, $ls);
}
// Adjust the start position for the next iteration.
$start += ($ls !== false ? ($ls + 1 - $chunk) + $chunk : $chunk);
// Parse the chunk.
$return .= $this->process($string);
}
}
// The input is less than 2KB so we can parse it efficiently.
else
{
// Parse the chunk.
$return .= $this->process($input);
}
return $return;
}
/**
* Method to process input and extract the plain text.
*
* @param string $input The input to process.
*
* @return string The plain text input.
*
* @since 2.5
*/
abstract protected function process($input);
}