Macro besl_struct_node 

macro_rules! besl_struct_node {
    (struct $name:ident { $($body:tt)* }) => { ... };
    (@fields $fields:ident [] ) => { ... };
    (@fields $fields:ident [$($field:tt)+] ) => { ... };
    (@fields $fields:ident [$($field:tt)*] , $($rest:tt)*) => { ... };
    (@fields $fields:ident [$($field:tt)*] $next:tt $($rest:tt)*) => { ... };
    (@emit $fields:ident []) => { ... };
    (@emit $fields:ident [$field:ident : $($field_type:tt)+]) => { ... };
}

Builds a BESL parser struct node from Rust-style struct syntax.