added artefact_in_view function for strict artefact -> view checking

(checks parent cache)

htdocs/lib/mahara.php

@@ -1023,6 +1023,19 @@ function can_view_view($view_id, $user_id=null) {
     return false;
 }
 
+function artefact_in_view($artefact, $view) {
+    $prefix = get_config('dbprefix');
+    $sql = 'SELECT a.id 
+            FROM mh_view_artefact a WHERE view = ? AND artefact = ?
+            UNION
+            SELECT c.parent 
+            FROM mh_view_artefact top JOIN mh_artefact_parent_cache c
+              ON c.parent = top.artefact 
+            WHERE top.view = ? AND c.artefact = ?';
+
+    return record_exists_sql($sql, array($view, $artefact, $view, $artefact));
+}
+
 function get_dir_contents($directory) {
     $contents = array();
     $dirhandle = opendir($directory);