89cbc78d3d
# Objective Be consistent with `Resource`s and `Components` and have `Event` types be more self-documenting. Although not susceptible to accidentally using a function instead of a value due to `Event`s only being initialized by their type, much of the same reasoning for removing the blanket impl on `Resource` also applies here. * Not immediately obvious if a type is intended to be an event * Prevent invisible conflicts if the same third-party or primitive types are used as events * Allows for further extensions (e.g. opt-in warning for missed events) ## Solution Remove the blanket impl for the `Event` trait. Add a derive macro for it. --- ## Changelog - `Event` is no longer implemented for all applicable types. Add the `#[derive(Event)]` macro for events. ## Migration Guide * Add the `#[derive(Event)]` macro for events. Third-party types used as events should be wrapped in a newtype.
120 lines
3.6 KiB
Rust
120 lines
3.6 KiB
Rust
use proc_macro::TokenStream;
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use proc_macro2::{Span, TokenStream as TokenStream2};
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use quote::quote;
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use syn::{parse_macro_input, parse_quote, DeriveInput, Ident, LitStr, Path, Result};
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pub fn derive_event(input: TokenStream) -> TokenStream {
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let mut ast = parse_macro_input!(input as DeriveInput);
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let bevy_ecs_path: Path = crate::bevy_ecs_path();
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ast.generics
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.make_where_clause()
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.predicates
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.push(parse_quote! { Self: Send + Sync + 'static });
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let struct_name = &ast.ident;
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let (impl_generics, type_generics, where_clause) = &ast.generics.split_for_impl();
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TokenStream::from(quote! {
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impl #impl_generics #bevy_ecs_path::event::Event for #struct_name #type_generics #where_clause {
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}
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})
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}
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pub fn derive_resource(input: TokenStream) -> TokenStream {
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let mut ast = parse_macro_input!(input as DeriveInput);
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let bevy_ecs_path: Path = crate::bevy_ecs_path();
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ast.generics
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.make_where_clause()
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.predicates
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.push(parse_quote! { Self: Send + Sync + 'static });
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let struct_name = &ast.ident;
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let (impl_generics, type_generics, where_clause) = &ast.generics.split_for_impl();
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TokenStream::from(quote! {
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impl #impl_generics #bevy_ecs_path::system::Resource for #struct_name #type_generics #where_clause {
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}
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})
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}
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pub fn derive_component(input: TokenStream) -> TokenStream {
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let mut ast = parse_macro_input!(input as DeriveInput);
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let bevy_ecs_path: Path = crate::bevy_ecs_path();
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let attrs = match parse_component_attr(&ast) {
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Ok(attrs) => attrs,
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Err(e) => return e.into_compile_error().into(),
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};
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let storage = storage_path(&bevy_ecs_path, attrs.storage);
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ast.generics
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.make_where_clause()
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.predicates
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.push(parse_quote! { Self: Send + Sync + 'static });
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let struct_name = &ast.ident;
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let (impl_generics, type_generics, where_clause) = &ast.generics.split_for_impl();
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TokenStream::from(quote! {
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impl #impl_generics #bevy_ecs_path::component::Component for #struct_name #type_generics #where_clause {
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type Storage = #storage;
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}
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})
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}
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pub const COMPONENT: &str = "component";
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pub const STORAGE: &str = "storage";
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struct Attrs {
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storage: StorageTy,
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}
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#[derive(Clone, Copy)]
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enum StorageTy {
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Table,
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SparseSet,
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}
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// values for `storage` attribute
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const TABLE: &str = "Table";
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const SPARSE_SET: &str = "SparseSet";
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fn parse_component_attr(ast: &DeriveInput) -> Result<Attrs> {
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let mut attrs = Attrs {
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storage: StorageTy::Table,
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};
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for meta in ast.attrs.iter().filter(|a| a.path().is_ident(COMPONENT)) {
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meta.parse_nested_meta(|nested| {
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if nested.path.is_ident(STORAGE) {
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attrs.storage = match nested.value()?.parse::<LitStr>()?.value() {
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s if s == TABLE => StorageTy::Table,
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s if s == SPARSE_SET => StorageTy::SparseSet,
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s => {
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return Err(nested.error(format!(
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"Invalid storage type `{s}`, expected '{TABLE}' or '{SPARSE_SET}'.",
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)));
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}
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};
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Ok(())
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} else {
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Err(nested.error("Unsuported attribute"))
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}
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})?;
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}
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Ok(attrs)
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}
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fn storage_path(bevy_ecs_path: &Path, ty: StorageTy) -> TokenStream2 {
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let typename = match ty {
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StorageTy::Table => Ident::new("TableStorage", Span::call_site()),
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StorageTy::SparseSet => Ident::new("SparseStorage", Span::call_site()),
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};
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quote! { #bevy_ecs_path::component::#typename }
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}
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