fn simulate_nfa()

in cli/src/generate/prepare_grammar/expand_tokens.rs [407:449]

• 40 lines of code
• 11 McCabe index (conditional complexity)

    fn simulate_nfa<'a>(grammar: &'a LexicalGrammar, s: &'a str) -> Option<(usize, &'a str)> {
        let start_states = grammar.variables.iter().map(|v| v.start_state).collect();
        let mut cursor = NfaCursor::new(&grammar.nfa, start_states);

        let mut result = None;
        let mut result_precedence = i32::MIN;
        let mut start_char = 0;
        let mut end_char = 0;
        for c in s.chars() {
            for (id, precedence) in cursor.completions() {
                if result.is_none() || result_precedence <= precedence {
                    result = Some((id, &s[start_char..end_char]));
                    result_precedence = precedence;
                }
            }
            if let Some(NfaTransition {
                states,
                is_separator,
                ..
            }) = cursor
                .transitions()
                .into_iter()
                .find(|t| t.characters.contains(c) && t.precedence >= result_precedence)
            {
                cursor.reset(states);
                end_char += c.len_utf8();
                if is_separator {
                    start_char = end_char;
                }
            } else {
                break;
            }
        }

        for (id, precedence) in cursor.completions() {
            if result.is_none() || result_precedence <= precedence {
                result = Some((id, &s[start_char..end_char]));
                result_precedence = precedence;
            }
        }

        result
    }