a0a3d8798b
# Objective - Add an `ExtractResourcePlugin` for convenience and consistency ## Solution - Add an `ExtractResourcePlugin` similar to `ExtractComponentPlugin` but for ECS `Resource`s. The system that is executed simply clones the main world resource into a render world resource, if and only if the main world resource was either added or changed since the last execution of the system. - Add an `ExtractResource` trait with a `fn extract_resource(res: &Self) -> Self` function. This is used by the `ExtractResourcePlugin` to extract the resource - Add a derive macro for `ExtractResource` on a `Resource` with the `Clone` trait, that simply returns `res.clone()` - Use `ExtractResourcePlugin` wherever both possible and appropriate
27 lines
855 B
Rust
27 lines
855 B
Rust
use proc_macro::TokenStream;
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use quote::quote;
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use syn::{parse_macro_input, parse_quote, DeriveInput, Path};
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pub fn derive_extract_resource(input: TokenStream) -> TokenStream {
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let mut ast = parse_macro_input!(input as DeriveInput);
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let bevy_render_path: Path = crate::bevy_render_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: Clone });
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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_render_path::extract_resource::ExtractResource for #struct_name #type_generics #where_clause {
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type Source = Self;
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fn extract_resource(source: &Self::Source) -> Self {
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source.clone()
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}
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}
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})
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}
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