Defining pseudo custom attributes in a macro

request.rs

macro_rules! request {
    (
        @parsing $(#[$attrs:meta])*; #[get($uri:expr)] $(#[$rest_attrs:meta])*
        struct $Name:ident;
        $($rest:tt)*
    ) => {
        request! {
            @GET($uri)
            $(#[$attrs])*
            $(#[$rest_attrs])*
            struct $Name;
            $($rest)*
        }
    };
    (
        @parsing $(#[$attrs:meta])*; #[post($uri:expr)] $(#[$rest_attrs:meta])*
        struct $Name:ident;
        $($rest:tt)*
    ) => {
        request! {
            @POST($uri)
            $(#[$attrs])*
            $(#[$rest_attrs])*
            struct $Name;
            $($rest)*
        }
    };
    (@parsing $(#[$attrs:meta])*; #[$attr:meta] $($rest:tt)*) => {
        request! { @parsing $(#[$attrs])* #[$attr]; $($rest)* }
    };
    (@parsing $(#[$attrs:meta])*; struct $Name:ident { $($body:tt)* }) => {
        compile_error!("expected URI");
    };
    (
        @$method:ident($uri:expr)
        $(#[$attrs:meta])*
        struct $Name:ident;
        $($rest:tt)*
    ) => {
        $(#[$attrs])*
        struct $Name;

        impl $Name {
            fn method() -> &'static str {
                stringify!($method)
            }

            fn uri() -> &'static str {
                $uri
            }
        }

        request! { $($rest)* }
    };
    (@ $($arg:tt)*) => {
        compile_error!(concat!(
            "invalid macro invocation: foo! { @ ",
            stringify!($($arg)*),
        ));
    };
    ($($body:tt)+) => {
        request! { @parsing; $($body)* }
    };
    () => {};
}

request! {
    #[derive(Clone)]
    #[get("https://example.com/get")]
    struct Get;

    #[post("https://example.com/post")]
    struct Post;
}

fn main() {
    let _ = Get.clone();
    assert_eq!(Get::method(), "GET");
    assert_eq!(Get::uri(), "https://example.com/get");
    assert_eq!(Post::method(), "POST");
    assert_eq!(Post::uri(), "https://example.com/post");
}