Macro encoder_function

macro_rules! encoder_function {
    ($eof:block,
     $body:block,
     $slf:ident,
     $src_consumed:ident,
     $source:ident,
     $dest:ident,
     $c:ident,
     $destination_handle:ident,
     $unread_handle:ident,
     $destination_check:ident,
     $name:ident,
     $input:ty,
     $source_struct:ident) => { ... };
}