Macro array_alias_enum

macro_rules! array_alias_enum {
    (
    $(
      pub enum<$($generic_k:tt: $generic_v:tt),*> $name:ident {
        type Parent = $parent:ty;
        type Item = $item:ty;
        $(
          $key:ident => $target_arr:ident;
        )*
      }
    )+
  ) => { ... };
}