98 lines
3.1 KiB
Rust
98 lines
3.1 KiB
Rust
use darling::FromMeta;
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use proc_macro2::TokenStream;
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use quote::{format_ident, quote};
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use crate::util::ctxt::Ctxt;
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use crate::util::path::ModulePrefix;
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#[derive(Debug, FromMeta)]
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struct Args {
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#[darling(default)]
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pool_size: Option<usize>,
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#[darling(default)]
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embassy_prefix: ModulePrefix,
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}
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pub fn run(args: syn::AttributeArgs, f: syn::ItemFn) -> Result<TokenStream, TokenStream> {
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let args = Args::from_list(&args).map_err(|e| e.write_errors())?;
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let embassy_prefix = args.embassy_prefix.append("embassy");
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let embassy_path = embassy_prefix.path();
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let pool_size: usize = args.pool_size.unwrap_or(1);
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let ctxt = Ctxt::new();
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if f.sig.asyncness.is_none() {
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ctxt.error_spanned_by(&f.sig, "task functions must be async");
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}
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if !f.sig.generics.params.is_empty() {
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ctxt.error_spanned_by(&f.sig, "task functions must not be generic");
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}
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if pool_size < 1 {
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ctxt.error_spanned_by(&f.sig, "pool_size must be 1 or greater");
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}
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let mut arg_names = Vec::new();
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let mut fargs = f.sig.inputs.clone();
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for arg in fargs.iter_mut() {
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match arg {
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syn::FnArg::Receiver(_) => {
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ctxt.error_spanned_by(arg, "task functions must not have receiver arguments");
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}
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syn::FnArg::Typed(t) => match t.pat.as_mut() {
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syn::Pat::Ident(id) => {
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arg_names.push(id.ident.clone());
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id.mutability = None;
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}
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_ => {
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ctxt.error_spanned_by(
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arg,
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"pattern matching in task arguments is not yet supported",
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);
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}
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},
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}
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}
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ctxt.check()?;
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let task_ident = f.sig.ident.clone();
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let task_inner_ident = format_ident!("__{}_task", task_ident);
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let mut task_inner = f;
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let visibility = task_inner.vis.clone();
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task_inner.vis = syn::Visibility::Inherited;
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task_inner.sig.ident = task_inner_ident.clone();
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let result = quote! {
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// This is the user's task function, renamed.
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// We put it outside the #task_ident fn below, because otherwise
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// the items defined there (such as POOL) would be in scope
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// in the user's code.
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#task_inner
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#visibility fn #task_ident(#fargs) -> #embassy_path::executor::SpawnToken<impl ::core::future::Future + 'static> {
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use ::core::future::Future;
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use #embassy_path::executor::SpawnToken;
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use #embassy_path::executor::raw::TaskPool;
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type Fut = impl Future + 'static;
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static POOL: TaskPool<Fut, #pool_size> = TaskPool::new();
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// Opaque type laundering, to obscure its origin!
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// Workaround for "opaque type's hidden type cannot be another opaque type from the same scope"
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// https://github.com/rust-lang/rust/issues/96406
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fn launder_tait(token: SpawnToken<impl Future+'static>) -> SpawnToken<impl Future+'static> {
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token
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}
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launder_tait(POOL.spawn(move || #task_inner_ident(#(#arg_names,)*)))
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}
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};
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Ok(result)
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}
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