* We create an instance that has a reference to this
* session, but is otherwise identical to the reference
* mapping.
*/
public synchronized Mapping getMapping(String filename,IRSession session){
Mapping map = mappings.get(filename);
if(map != null)return map.clone(session);
if(map_paths.indexOf(filename)<0){
throw new RuntimeException("Bad Mapping File: "+filename+" For the rule set: "+name.stringValue());
}
map = Mapping.newMapping(rd, session, filename);
mappings.put(filename, map);
return map.clone(session);
}