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|
use darling::export::NestedMeta;
use darling::FromMeta;
use proc_macro2::{Span, TokenStream};
use quote::{format_ident, quote};
use syn::{parse_quote, Expr, ExprLit, ItemFn, Lit, LitInt, ReturnType, Type};
use crate::util::ctxt::Ctxt;
#[derive(Debug, FromMeta)]
struct Args {
#[darling(default)]
pool_size: Option<syn::Expr>,
}
pub fn run(args: &[NestedMeta], f: syn::ItemFn) -> Result<TokenStream, TokenStream> {
let args = Args::from_list(args).map_err(|e| e.write_errors())?;
let pool_size = args.pool_size.unwrap_or(Expr::Lit(ExprLit {
attrs: vec![],
lit: Lit::Int(LitInt::new("1", Span::call_site())),
}));
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 !f.sig.generics.where_clause.is_none() {
ctxt.error_spanned_by(&f.sig, "task functions must not have `where` clauses");
}
if !f.sig.abi.is_none() {
ctxt.error_spanned_by(&f.sig, "task functions must not have an ABI qualifier");
}
if !f.sig.variadic.is_none() {
ctxt.error_spanned_by(&f.sig, "task functions must not be variadic");
}
match &f.sig.output {
ReturnType::Default => {}
ReturnType::Type(_, ty) => match &**ty {
Type::Tuple(tuple) if tuple.elems.is_empty() => {}
Type::Never(_) => {}
_ => ctxt.error_spanned_by(
&f.sig,
"task functions must either not return a value, return `()` or return `!`",
),
},
}
let mut args = 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) => {
id.mutability = None;
args.push((id.clone(), t.attrs.clone()));
}
_ => {
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();
// assemble the original input arguments,
// including any attributes that may have
// been applied previously
let mut full_args = Vec::new();
for (arg, cfgs) in args {
full_args.push(quote!(
#(#cfgs)*
#arg
));
}
#[cfg(feature = "nightly")]
let mut task_outer: ItemFn = parse_quote! {
#visibility fn #task_ident(#fargs) -> ::embassy_executor::SpawnToken<impl Sized> {
trait Task {
type Fut: core::future::Future + 'static;
fn construct(#fargs) -> Self::Fut;
}
struct ThisTask;
impl Task for ThisTask {
type Fut = impl core::future::Future + 'static;
fn construct(#fargs) -> Self::Fut {
#task_inner_ident(#(#full_args,)*)
}
}
const POOL_SIZE: usize = #pool_size;
static POOL: ::embassy_executor::raw::TaskPool<<ThisTask as Task>::Fut, POOL_SIZE> = ::embassy_executor::raw::TaskPool::new();
unsafe { POOL._spawn_async_fn(move || ThisTask::construct(#(#full_args,)*)) }
}
};
#[cfg(not(feature = "nightly"))]
let mut task_outer: ItemFn = parse_quote! {
#visibility fn #task_ident(#fargs) -> ::embassy_executor::SpawnToken<impl Sized> {
const POOL_SIZE: usize = #pool_size;
static POOL: ::embassy_executor::_export::TaskPoolRef = ::embassy_executor::_export::TaskPoolRef::new();
unsafe { POOL.get::<_, POOL_SIZE>()._spawn_async_fn(move || #task_inner_ident(#(#full_args,)*)) }
}
};
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)
}
|
