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feat: Add derive macro for PrefabData
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,112 @@ | ||
| use proc_macro2::TokenStream; | ||
| use syn::{Data, DeriveInput, Ident, Meta, NestedMeta, Type}; | ||
|
|
||
| pub fn impl_event_reader(ast: &DeriveInput) -> TokenStream { | ||
| let event_name = &ast.ident; | ||
|
|
||
| let mut reader_name: Option<Ident> = None; | ||
| for meta in ast | ||
| .attrs | ||
| .iter() | ||
| .filter(|attr| attr.path.segments[0].ident == "reader") | ||
| .map(|attr| { | ||
| attr.interpret_meta() | ||
| .expect("reader attribute incorrectly defined") | ||
| }) { | ||
| match meta { | ||
| Meta::List(l) => { | ||
| for nested_meta in l.nested.iter() { | ||
| match *nested_meta { | ||
| NestedMeta::Meta(Meta::Word(ref word)) => { | ||
| reader_name = Some(word.clone()); | ||
| } | ||
| _ => panic!("reader attribute does not contain a single name"), | ||
| } | ||
| } | ||
| } | ||
| _ => (), | ||
| }; | ||
| } | ||
|
|
||
| let reader_name = reader_name.expect(&format!( | ||
| r#" | ||
| #[derive(EventReader)] requested for {}, but #[reader(SomeEventReader)] attribute is missing | ||
| Example usage: | ||
| #[derive(EventReader)] | ||
| #[reader(SomeEventReader)] | ||
| pub enum SomeEvent {{ | ||
| One(Event1), | ||
| Two(Event2), | ||
| }} | ||
| "#, | ||
| event_name | ||
| )); | ||
|
|
||
| let tys = collect_field_types(&ast.data); | ||
| let tys = &tys; | ||
| let names = collect_variant_names(&ast.data); | ||
| let names = &names; | ||
|
|
||
| let reads : Vec<_> = (0..tys.len()).map(|n| { | ||
| let variant = &names[n]; | ||
| quote! { | ||
| events.extend(data.#n.read(self.#n.as_mut().expect("ReaderId undefined, has setup been run?")).cloned().map(|e| #event_name::#variant(e))); | ||
| } | ||
| }).collect(); | ||
| let setups: Vec<_> = (0..tys.len()) | ||
| .map(|n| { | ||
| let ty = &tys[n]; | ||
| quote! { | ||
| self.#n = Some(res.fetch_mut::<EventChannel<#ty>>().register_reader()); | ||
| } | ||
| }).collect(); | ||
| quote! { | ||
| #[allow(missing_docs)] | ||
| #[derive(Default)] | ||
| pub struct #reader_name( | ||
| #(Option<ReaderId<#tys>>, )* | ||
| ); | ||
|
|
||
| impl<'a> EventReader<'a> for #reader_name { | ||
| type SystemData = ( | ||
| #(Read<'a, EventChannel<#tys>>),* | ||
| ); | ||
| type Event = #event_name; | ||
|
|
||
| fn read(&mut self, data: Self::SystemData, events: &mut Vec<#event_name>) { | ||
| #(#reads)* | ||
| } | ||
|
|
||
| fn setup(&mut self, res: &mut Resources) { | ||
| <Self::SystemData as SystemData<'a>>::setup(res); | ||
| #(#setups)* | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| fn collect_field_types(ast: &Data) -> Vec<Type> { | ||
| let variants = match *ast { | ||
| Data::Enum(ref variants) => &variants.variants, | ||
| _ => panic!("EventReader derive only support enums"), | ||
| }; | ||
| variants | ||
| .iter() | ||
| .map(|v| { | ||
| v.fields | ||
| .iter() | ||
| .next() | ||
| .expect("Event enum variant does not contain an inner event type") | ||
| .ty | ||
| .clone() | ||
| }).collect() | ||
| } | ||
|
|
||
| fn collect_variant_names(ast: &Data) -> Vec<Ident> { | ||
| let variants = match *ast { | ||
| Data::Enum(ref variants) => &variants.variants, | ||
| _ => panic!("EventReader derive only support enums"), | ||
| }; | ||
| variants.iter().map(|v| v.ident.clone()).collect() | ||
| } |
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