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use darling::FromMeta;
use proc_macro2::TokenStream;
use quote::{format_ident, quote};
use syn::{parse_quote, ItemFn};
use crate::util::ctxt::Ctxt;
#[derive(Debug, FromMeta)]
struct Args {
#[darling(default)]
pool_size: Option<usize>,
}
pub fn run(args: syn::AttributeArgs, f: syn::ItemFn) -> Result<TokenStream, TokenStream> {
let args = Args::from_list(&args).map_err(|e| e.write_errors())?;
let pool_size: usize = args.pool_size.unwrap_or(1);
let ctxt = Ctxt::new();
if f.sig.asyncness.is_none() {
ctxt.error_spanned_by(&f.sig, "task functions must be async");
}
if !f.sig.generics.params.is_empty() {
ctxt.error_spanned_by(&f.sig, "task functions must not be generic");
}
if pool_size < 1 {
ctxt.error_spanned_by(&f.sig, "pool_size must be 1 or greater");
}
let mut arg_names = Vec::new();
let mut fargs = f.sig.inputs.clone();
for arg in fargs.iter_mut() {
match arg {
syn::FnArg::Receiver(_) => {
ctxt.error_spanned_by(arg, "task functions must not have receiver arguments");
}
syn::FnArg::Typed(t) => match t.pat.as_mut() {
syn::Pat::Ident(id) => {
arg_names.push(id.ident.clone());
id.mutability = None;
}
_ => {
ctxt.error_spanned_by(arg, "pattern matching in task arguments is not yet supported");
}
},
}
}
ctxt.check()?;
let task_ident = f.sig.ident.clone();
let task_inner_ident = format_ident!("__{}_task", task_ident);
let mut task_inner = f;
let visibility = task_inner.vis.clone();
task_inner.vis = syn::Visibility::Inherited;
task_inner.sig.ident = task_inner_ident.clone();
let mut task_outer: ItemFn = parse_quote! {
#visibility fn #task_ident(#fargs) -> ::embassy_executor::SpawnToken<impl Sized> {
type Fut = impl ::core::future::Future + 'static;
static POOL: ::embassy_executor::raw::TaskPool<Fut, #pool_size> = ::embassy_executor::raw::TaskPool::new();
unsafe { POOL._spawn_async_fn(move || #task_inner_ident(#(#arg_names,)*)) }
}
};
task_outer.attrs.append(&mut task_inner.attrs.clone());
let result = quote! {
// This is the user's task function, renamed.
// We put it outside the #task_ident fn below, because otherwise
// the items defined there (such as POOL) would be in scope
// in the user's code.
#[doc(hidden)]
#task_inner
#task_outer
};
Ok(result)
}
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