Function rustc_ap_rustc_lexer::unescape::unescape_str

pub fn unescape_str<F>(literal_text: &str, callback: &mut F) where
    F: FnMut(Range<usize>, Result<char, EscapeError>), 

Takes a contents of a string literal (without quotes) and produces a sequence of escaped characters or errors. Values are returned through invoking of the provided callback.