@Override
public void checkUp() throws QueryException {
for (final Let c : copies) c.checkUp();
final Expr m = expr[0];
m.checkUp();
if (!m.isVacuous() && !m.has(Flag.UPD)) throw UPMODIFY.get(info);
checkNoUp(expr[1]);
}
/**
* Ensures that all specified expressions are vacuous or either updating or non-updating.
* Otherwise, throws an exception.
*
* @param exprs expressions to be checked
* @throws QueryException query exception
*/
void checkAllUp(final Expr... exprs) throws QueryException {
// updating state: 0 = initial state, 1 = updating, -1 = non-updating
int s = 0;
for (final Expr expr : exprs) {
expr.checkUp();
if (expr.isVacuous()) continue;
final boolean u = expr.has(Flag.UPD);
if (u && s == -1 || !u && s == 1) throw UPALL.get(info, description());
s = u ? 1 : -1;
}
}
/**
* Ensures that the specified expression performs no updates. Otherwise, throws an exception.
*
* @param expr expression (may be {@code null})
* @throws QueryException query exception
*/
protected void checkNoUp(final Expr expr) throws QueryException {
if (expr == null) return;
expr.checkUp();
if (expr.has(Flag.UPD)) throw UPNOT_X.get(info, description());
}