extern crate proc_macro;
use bevy_macro_utils::BevyManifest;
use quote::{quote, ToTokens};
use syn::*;
use uuid::Uuid;
pub fn type_uuid_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let ast: DeriveInput = syn::parse(input).unwrap();
let bevy_reflect_path: Path = BevyManifest::default().get_path("bevy_reflect");
let name = &ast.ident;
let (impl_generics, type_generics, _) = &ast.generics.split_for_impl();
assert!(
impl_generics.to_token_stream().is_empty() && type_generics.to_token_stream().is_empty(),
"#[derive(TypeUuid)] is not supported for generics.",
);
let mut uuid = None;
for attribute in ast.attrs.iter().filter_map(|attr| attr.parse_meta().ok()) {
let name_value = if let Meta::NameValue(name_value) = attribute {
name_value
} else {
continue;
};
if name_value
.path
.get_ident()
.map(|i| i != "uuid")
.unwrap_or(true)
{
continue;
}
let uuid_str = match name_value.lit {
Lit::Str(lit_str) => lit_str,
_ => panic!("`uuid` attribute must take the form `#[uuid = \"xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx\"`."),
};
uuid = Some(
Uuid::parse_str(&uuid_str.value())
.expect("Value specified to `#[uuid]` attribute is not a valid UUID."),
);
}
let uuid =
uuid.expect("No `#[uuid = \"xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx\"` attribute found.");
let bytes = uuid
.as_bytes()
.iter()
.map(|byte| format!("{:#X}", byte))
.map(|byte_str| syn::parse_str::<LitInt>(&byte_str).unwrap());
let gen = quote! {
impl #bevy_reflect_path::TypeUuid for #name {
const TYPE_UUID: #bevy_reflect_path::Uuid = #bevy_reflect_path::Uuid::from_bytes([
#( #bytes ),*
]);
}
};
gen.into()
}