Function capture_parenthesized_token

src/email.rs:718–754

(line: &str, key: &str)

}

fn capture_parenthesized_token(line: &str, key: &str) -> Option<String> {
    let marker = format!("{key} ");
    let start = line.find(&marker)? + marker.len();
    let rest = line[start..].trim_start();
    if !rest.starts_with('(') {
        return None;
    }

    let mut depth = 0usize;
    let mut output = String::new();
    for ch in rest.chars() {
        match ch {
            '(' => {
                depth = depth.saturating_add(1);
                if depth > 1 {
                    output.push(ch);
                }
            }
            ')' => {
                if depth == 1 {
                    return Some(output);
                }
                if depth > 1 {
                    output.push(ch);
                }
                depth = depth.saturating_sub(1);
            }
            _ => {
                if depth >= 1 {
                    output.push(ch);
                }
            }
        }
    }

    None
}

fn parse_headers(literal: &[u8]) -> BTreeMap<String, String> {
    let mut headers: BTreeMap<String, String> = BTreeMap::new();