Module analyzer 

Structs

AllowEmptyRuleAnalyzer

Analyze which rules can match the empty string. Returns the sorted list of nullable rule ids.

RuleRefGraphFinder

Build the inverted rule reference graph: graph[referee] is the sorted, deduplicated list of rules that reference referee.

UsedRulesAnalyzer

Collect every rule reachable from the root rule (transitive closure over rule refs, repeats and tag dispatches). Used for dead-code elimination. Returns the reachable rule ids in ascending order.