Function is_fstring_prefix

compiler/src/modules/lexer/tables.rs:126–135

(s: &[u8])

/* f-string prefix: f, F, fr, Fr, fR, FR, rf, rF, Rf, RF. */
#[inline]
pub fn is_fstring_prefix(s: &[u8]) -> bool {
    match s.len() {
        1 => matches!(s[0], b'f' | b'F'),
        2 => matches!(
            (s[0], s[1]),
            (b'f' | b'F', b'r' | b'R') | (b'r' | b'R', b'f' | b'F')
        ),
        _ => false,
    }
}

/* Regular string prefix: r, R, u, U. The b/B variants live in `is_bytes_prefix` to emit a distinct `Bytes` token. */
#[inline]