<?php
// ##################################################################################
// Title                     : Class RDDL_parser
// Version                   : 1.0
// Author                    : Luis Argerich (hide@address.com)
// Last modification date    : 06-20-2002
// Description               : A class to parse RDDL documents.
//                             Can parse documents from files or URIs.
//                             Once you parsed the RDDL document you get a list of resources
//                             to process them.
// ##################################################################################
// History: 
// 06-20-2002                : First version of this class.
// ##################################################################################
// To-Dos:
//
// ##################################################################################
// How to use it:
// Read the documentation in rddl_parser.html
// ##################################################################################

if(defined("_class_rddl_parser_is_included")) {
  // do nothing since the class is already included  
} else {
  define("_class_rddl_parser_is_included",1);

define("NAMESPACE_SEPARATOR_CHAR","^");
define("RDDL_NAMESPACE_NAME","http://www.rddl.org/");
define("XLINK_NAMESPACE_NAME","http://www.w3.org/1999/xlink");



class RDDL_parser {
  var $resources=Array();
  var $base='';
  var $parser;
  var $error='';

  function get_error() {
    return $this->error; 
  }
     
  function get_resources() {
    return $this->resources;
  }
  
  function rddl_parse($rddl) {
    $this->base=$rddl;
    $this->parser = xml_parser_create_ns("",NAMESPACE_SEPARATOR_CHAR);
    xml_set_object($this->parser,&$this);
    xml_parser_set_option($this->parser, XML_OPTION_CASE_FOLDING, false);
    xml_set_element_handler($this->parser, "startElement", "endElement");
    if (!($fp = fopen($rddl, "r"))) {
      $this->error="Cannot open $rddl";
      return false;
    }
    while ($data = fread($fp, 4096)) {
      if (!xml_parse($this->parser, $data, feof($fp))) {
        $this->error="XML error: ".xml_error_string(xml_get_error_code($this->parser))." at line ".xml_get_current_line_number($this->parser);
        return false;                    
      }
    }
    xml_parser_free($this->parser);
    return true;
  }

  function startElement($parser, $name, $attrs) {
    $name_components=explode(NAMESPACE_SEPARATOR_CHAR,$name);
    if(strstr($name_components[0],RDDL_NAMESPACE_NAME)) {
      
      foreach($attrs as $atk =>$atv) {
        if(strstr($atk,XLINK_NAMESPACE_NAME)) {
           $atrib_parts=explode(NAMESPACE_SEPARATOR_CHAR,$atk);
           $atk=$atrib_parts[1];
           
        }
        if($atk=="href") {
          $this->_resolve_uri_reference($this->base,$atv,$buffer,0);
          $atv=$buffer;
          
        }
      
        $elem[$atk]=$atv;
      }
      $this->resources[]=$elem;
    }
    //print "$name<br/>";
  }

  function endElement($parser, $name) {
  }


  function _parse_uri($uri,$buffer,$len,&$scheme,&$authority,&$path,&$query,&$fragment ) {
    $parsed=parse_url($uri);
    if(isset($parsed["scheme"])) {
      $scheme=$parsed["scheme"];} else {
  	  $scheme='';
    }
    if(isset($parsed["host"])) {
      $host=$parsed["host"];} else {
  	  $host='';
    }
    if(isset($parsed["host"])) {
      $authority=$parsed["host"];} else {
  	  $authority='';
    }
    if(isset($parsed["path"])) {
      $path=$parsed["path"];} else {
  	  $path='';
    }
    if(isset($parsed["query"])) {
      $query=$parsed["query"];} else {
    	$query='';
    }
    if(isset($parsed["fragment"])) {
      $fragment=$parsed["fragment"];} else {
    	$fragment='';
    }
  }


  function _resolve_uri_reference($base_uri,$reference_uri,&$buffer,$length ) {
	$base_buffer='';
	$reference_buffer='';
	$path_buffer='';

	$buffer = '';

	$this->_parse_uri($reference_uri,$reference_buffer,strlen( $reference_buffer ),$reference_scheme,$reference_authority,
		$reference_path,$reference_query,$reference_fragment );

	if( $reference_scheme == ''
		&& $reference_authority == ''
		&& $reference_path == ''
		&& $reference_query == '' )
	{
		$buffer=$base_uri;

		if( $reference_fragment != '' )
		{
			$buffer.= "#" ;
			$buffer.=$reference_fragment;
		}
	}
	else if( $reference_scheme != '' )
	{
		$buffer=$reference_uri;
	}
	else
	{
		$this->_parse_uri(
			$base_uri,
			$base_buffer,
			strlen( $base_buffer ),
			$base_scheme,
			$base_authority,
			$base_path,
			$base_query,
			$base_fragment );

		$result_scheme = $base_scheme;

		if( $reference_authority != '' )
		{
			$result_authority = $reference_authority;
		}
		else
		{
			$result_authority = $base_authority;

			if( $reference_path != '' 
				&& ( ($reference_path{0} == '/')  
					|| ($reference_path{0} ==  '\\')  ) )
			{
				$result_path = $reference_path;
			}
			else
			{
				$p = '';
				
				$result_path = $path_buffer;

				$path_buffer='';

				$p = strstr( $base_path,  '/'  );

				if( !$p )
				{
					$p = strstr( $base_path, '\\'  );
				}

				if( $p )
				{
					
					$path_buffer.=$base_path;
					
					//while( s <= p )
					//{
					//	*d++ = *s++;
					//}

					//*d++ = 0;
					
				}

				if( $reference_path != '' )
				{
					$path_buffer.=$reference_path;
				}

				{
					//remove all occurrences of "./" 
					//print($path_buffer);
					$path_buffer=preg_replace("/\/\.\//","/",$path_buffer);
					$path_buffer=preg_replace("/\/([^\/\.])*\/..$/","/",$path_buffer);
					while(preg_match("/\.\./",$path_buffer)) {
					  $path_buffer=preg_replace("/\/([^\/\.]*)\/..\//","/",$path_buffer);
					}
					$path_buffer=preg_replace("/\.$/","",$path_buffer);

				}

			}
		}
		
		// This replaces the C pointer assignament
		
		$result_path = $path_buffer;
		if( $result_scheme != '' )
		{
			$buffer=$result_scheme;
			$buffer.=":";
		}

		if( $result_authority != '' )
		{
			$buffer.="//";
			$buffer.=$result_authority;
		}

		if( $result_path != '' )
		{
			
			$buffer.=$result_path;
		}

		if( $reference_query != '' )
		{
			$buffer.="?";
			$buffer.=$reference_query;
		}

		if( $reference_fragment != '' )
		{
			$buffer.="#";
			$buffer.=$reference_fragment;
		}
	}
  }
  
  
}

}
?>