Macro helix::codegen

macro_rules! codegen {
    { [ $($ast:tt)* ] } => { ... };
    {
        type: top,
        classes: [ $($class:tt)* ],
        buffer: []
    } => { ... };
    {
        type: top,
        classes: [
            $($class:tt)*
        ],
        buffer: [
            {
                type: class,
                rust_name: $rust_name:tt,
                ruby_name: $ruby_name:tt,
                meta: { pub: $pub:tt, reopen: $reopen:tt },
                struct: $struct:tt,
                methods: [ $($method:tt)* ]
            }
            $($rest:tt)*
        ]
    } => { ... };
    {
        type: done,
        classes: [ $(
            {
                rust_name: $rust_name:tt,
                ruby_name: $ruby_name:tt,
                struct: { $($struct:tt)* },
                methods: [ $($method:tt)* ]
            }
        )* ]
    } => { ... };
}