Ordering Rejectable Stacks in SGLR Parsing

Scannerless Generalised LR can parse context-free grammars extended with conjunction-with-negation, represented by reject rules. To handle reject rules correctly, Visser defines a specific ordering between states that can be reduced during parsing: first reduce non-rejectable states, then rejectable states. However, he remarks that in specific situations an ordering between rejectable states is required for correct parsing results, for example when encoding intersections with reject rules. The question of how to order rejectable states was left open. In this work, we present a solution that orders stacks topped by rejectable states.