Shared via Rust Playground

playground.rs

macro_rules! item {
    ( $i:item ) => ( #[derive(Debug)] $i )
}

macro_rules! vertex_struct {
    ( $name:ident { $( $n:ident : $t:ty ),* }) => ( item! { struct $name { $( $n: $t ),* } })
}

macro_rules! constant_struct {
    ( $name:ident $( $body:tt )* ) => ( item! { struct $name $( $body )* })
}

macro_rules! pipeline_struct {
    ( $name:ident $( $body:tt )* ) => ( item! { struct $name $( $body )* })
}

macro_rules! dispatch {
    ( vertex struct $name:ident $body:tt )
    => ( vertex_struct! { $name $body } );
    ( constant struct $name:ident $body:tt )
    => ( constant_struct! { $name $body } );
    ( pipeline struct $name:ident $body:tt )
    => ( pipeline_struct! { $name $body } );
}

macro_rules! defs {
    ( $( $modifier:tt struct $name:ident $body:tt )* ) 
    => ( $( dispatch! { $modifier struct $name $body } )* )
}

defs! {
    vertex struct Vtx { p: [f32; 2], c: [f32; 3] }
    pipeline struct Pipe { vbuf: Vtx }
}

fn main() {
    let pipe = Pipe { vbuf: Vtx { p: [ 1.5, 2.5 ], c: [ 0.0, 0.0, 0.0 ] } };
    println!("{:?}", pipe);
}