<?php

// the root of classes used to filter HTML
// 
                     
class BaseHTMLFilter
{
	var $_parser;
	var $_out_data = '';
	var $_options; // abstract options

	var $_stack = array();
	var $_stack_index = 0;

	function BaseHTMLFilter($options = array(), $init_parser = NULL)
	{
		$this->_options = $options;
		$this->_parser = $init_parser;
	}

/////////////////////////////////////
// actual job is done here
	function filter($content, $object)
	{
		require_once('XML/HTMLSax3.php');
		if(!$this->_parser)
			$this->_parser = new XML_HTMLSax3();

		$this->_parser->set_object($this);
		$this->_parser->set_element_handler('_doOpenTag', '_doCloseTag');
        $this->_parser->set_data_handler('_doData');
        $this->_parser->set_pi_handler('_doPITag');
        $this->_parser->set_jasp_handler('_doJASPTag');
        $this->_parser->set_escape_handler('_doEscape');
		
		$this->_out_data = '';
		$this->_parser->parse($content);
		return $this->_out_data;
	}
/////////////////////////////////////

// privates
	function _doOpenTag(&$Parser, $TagName, $Attr, $Empty)
	{
		if(!$Empty)
			$this->_push_tag($TagName, $Attr);
		$this->doOpenTag($Parser, $TagName, $Attr, $Empty);
	}

	function _doCloseTag(&$Parser, $TagName, $Empty)
	{
		$this->doCloseTag($Parser, $TagName, $Empty);
		if(!$Empty)
			$this->_tag_close($TagName);
	}

	function _doData(&$Parser, $Data)
	{
		$this->doData($Parser, $Data);
	}

	function _doPITag(&$Parser, $Target, $Data)
	{
		$this->doPITag($Parser, $Target, $Data);
	}

	function _doJASPTag(&$Parser, $Data)
	{
		$this->doJASPTag($Parser, $Data);
	}

	function _doEscape(&$Parser, $Data)
	{
		$this->doEscape($Parser, $Data);
	}

// utils
	function _makeAttributeString($Attr)
	{
		$result = array();
		foreach($Attr as $k => $v){
			if($v === NULL)
				$result[] = $k;
			else
				$result[] = "$k=\"$v\"";
		}

		return implode(' ', $result);
	}

	function _dump($str)
	{
		$this->_out_data .= $str;
	}

// utils - stack support
	function _push_tag($tag_name, $attr)
	{
		$tag_name = strtolower($tag_name);
		$entry = array(
			'tag' => $tag_name,
			'attr' => $attr,
		);
		$this->_stack[$this->_stack_index] = $entry;
		$this->_stack_index++;
	}

	function _pop_tag()
	{
		$result = NULL;
		if($this->_stack_index > 0){
			$this->_stack_index--;
			$result = $this->_stack[$this->_stack_index];
		}
		return $result;
	}

	function _tag_nest_count($tag_name)
	{
		$tag_name = strtolower($tag_name);
		$result = 0;
		for($i = 0; $i < $this->_stack_index; $i++)
			if($this->_stack[$i]['tag'] == $tag_name)
				$result++;

		return $result;
	}

	function _tag_close($tag_name)
	{
		$tag_name = strtolower($tag_name);
		$count = $this->_tag_nest_count($tag_name);
		if($count > 0){
			do {
				$this->_stack_index--;
			} while($this->_stack[$this->_stack_index]['tag'] != $tag_name);
			return true;
		} else
			return false;
	}


// abstract options support
	function setOption($name, $value = 1)
	{
		$this->_options[$name] = $value;
	}

	function getOption($name)
	{
		return $this->_options[$name];
	}

	function removeOption($name)
	{
		$result = NULL;
		if(isset($this->_options[$name])){
			$result = $this->_options[$name];
			unset($this->_options[$name]);
		}
		return $result;
	}

// public overrides
	function doOpenTag(&$Parser, $TagName, $Attr, $Empty)
	{
		$attrib_string = $this->_makeAttributeString($Attr);
		$this->_dump("<$TagName" . ($attrib_string? " $attrib_string": '') . ($Empty? '/>': '>'));
	}

	function doCloseTag(&$Parser, $TagName, $Empty)
	{
		if(!$Empty)
			$this->_dump("</$TagName>");
	}

	function doData(&$Parser, $Data)
	{
		$this->_dump($Data);
	}

	function doPITag(&$Parser, $Target, $Data)
	{
		$this->_dump("<?$Target $Data?>");
	}

	function doJASPTag(&$Parser, $Data)
	{
		$this->_dump("<%$Data%>");
	}

	function doEscape(&$Parser, $Data)
	{
		$this->_dump("<!$Data>");
	}

}


?>