Struct EarleyDynamicMatchers 

pub struct EarleyDynamicMatchers { /* private fields */ }

The dynamic-Earley lexer built once at construction (the seam mirroring Lark’s EarleyRegexpMatcher.__init__): the per-terminal forward matchers + parallel terminal-priority vector. A zero-width / bad regexp raises the GrammarError here (construction), never mid-parse — every subsequent parse borrows this by reference (see super::EarleyLexerSource).