<?php
/* Average - from RDF
   With RNG validation and error-message handling.
   Failed validation does not stop processing !
   */

function average_R($doc, $nsRdf, $nsEpita){

    $start = $doc->documentElement;
	
	$k = 0; //number of students/marks
	$s = 0; //total
	$eleves = $start->getElementsByTagNameNS($nsRdf, "Description");
	foreach( $eleves as $eleve ){ // foreach works with a NodeList !
		$name = substr($eleve->getAttributeNS($nsRdf,"about"), 1); // suppress '#'
		$mark = $eleve->getElementsByTagNameNS($nsEpita, "mark")->item(0)->firstChild->wholeText;;
		
		echo "$name 's mark is $mark\n";
		$s += $mark;
		$k++;
	}
	if( $k == 0 ){
		die("empty data");
	}else{
		return $s/$k;
	}
}// average_R
	
function reading ($fichIn, $schmFich){
	$doc = new DOMDocument();
	$doc->load($fichIn);
	if( !$doc->schemaValidate($schmFich) ){
  		foreach( libxml_get_errors() as $error ){
     		echo "\t$error->message";
  		}
  		die("Invalid document\n");
	}
	$rdfUri = "http://www.w3.org/1999/02/22-rdf-syntax-ns#";
	$epitaUri = "http://epita/masters/international/";
	$moy = average_R($doc, $rdfUri, $epitaUri);
	echo "\nAverage : $moy\n";
}//reading

reading($argv[1], $argv[2]);
?>