Generate a struct with a proc macro

macro_struct.rs

/// The schema proc macro:
/// Example:
///
/// schema! {
///   Users {
///     id: "integer primary key not null"
///   }
/// }
#[proc_macro]
pub fn schema(s: TokenStream) -> TokenStream {
    match schema_macro(s.into()) {
        Ok(s) => s.to_token_stream().into(),
        Err(e) => e.to_compile_error().into(),
    }
}

/// Generates the structs for the schema macro
fn schema_macro(body: TokenStream2) -> Result<TokenStream2> {
    let table = syn::parse::<Table>(body.into())?;
    let name = table.name;
    let fields: Vec<TokenStream2> = table
        .field_values
        .iter()
        .map(|fv| match &fv.expr {
            Expr::Lit(ExprLit { lit, .. }) => match lit {
                syn::Lit::Str(s) => {
                    let member = &fv.member;
                    quote! { #[doc = #s] pub #member: &'static str }
                }
                _ => todo!(),
            },
            _ => todo!(),
        })
        .collect();

    Ok(quote! {
        #[derive(Clone, Default, Debug, Copy)]
        pub struct #name {
            #(#fields,)*
        }
    })
}