Macro ascii_case_insensitive_phf_map 

macro_rules! ascii_case_insensitive_phf_map {
    ($name: ident -> $ValueType: ty = { $( $key: tt => $value: expr ),+ }) => { ... };
    ($name: ident -> $ValueType: ty = { $( $key: tt => $value: expr, )+ }) => { ... };
}

Fast implementation of ascii_case_insensitive_map! using a phf map. See ascii_case_insensitive_map! above for docs