*/
static class Lookup extends ROperator {
Lookup(){super("lookup");}
public void execute(DTState state) throws RulesException {
RName name = state.datapop().rNameValue();
IRObject value = state.find(name);
if(value == null){
throw new RulesException(
"undefined",
"Lookup",
"Could not find a value for "+name.stringValue()+" in the current context."
);
}
state.datapush(value);
}