bevy/crates/bevy_derive/src/component_set.rs
2020-06-25 11:21:56 -07:00

50 lines
1.7 KiB
Rust

use crate::modules::{get_modules, get_path};
use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, Data, DataStruct, DeriveInput, Fields, Ident};
pub fn derive_component_set(input: TokenStream) -> TokenStream {
let ast = parse_macro_input!(input as DeriveInput);
let fields = match &ast.data {
Data::Struct(DataStruct {
fields: Fields::Named(fields),
..
}) => &fields.named,
_ => panic!("expected a struct with named fields"),
};
let modules = get_modules(&ast);
let bevy_app_path = get_path(&modules.bevy_app);
let legion_path = get_path(&modules.legion);
let component_fields = fields
.iter()
.map(|field| field.ident.as_ref().unwrap())
.collect::<Vec<&Ident>>();
let generics = ast.generics;
let (impl_generics, ty_generics, _where_clause) = generics.split_for_impl();
let struct_name = &ast.ident;
TokenStream::from(quote! {
impl #impl_generics #bevy_app_path::ComponentSet for #struct_name#ty_generics {
fn insert(self, world: &mut #legion_path::prelude::World) -> #legion_path::prelude::Entity {
*world.insert((),
vec![(
#(self.#component_fields,)*
)
]).first().unwrap()
}
fn insert_command_buffer(self, command_buffer: &mut #legion_path::prelude::CommandBuffer) -> #legion_path::prelude::Entity {
*command_buffer.insert((),
vec![(
#(self.#component_fields,)*
)
]).first().unwrap()
}
}
})
}