macros: cleanup, make work in stable.

embassy-macros/src/macros/task.rs

@@ -0,0 +1,90 @@
+use darling::FromMeta;
+use proc_macro2::TokenStream;
+use quote::{format_ident, quote};
+
+use crate::util::ctxt::Ctxt;
+use crate::util::path::ModulePrefix;
+
+#[derive(Debug, FromMeta)]
+struct Args {
+    #[darling(default)]
+    pool_size: Option<usize>,
+    #[darling(default)]
+    send: bool,
+    #[darling(default)]
+    embassy_prefix: ModulePrefix,
+}
+
+pub fn run(args: syn::AttributeArgs, mut f: syn::ItemFn) -> Result<TokenStream, TokenStream> {
+    let args = Args::from_list(&args).map_err(|e| e.write_errors())?;
+
+    let embassy_prefix = args.embassy_prefix.append("embassy");
+    let embassy_path = embassy_prefix.path();
+
+    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: syn::punctuated::Punctuated<syn::Ident, syn::Token![,]> =
+        syn::punctuated::Punctuated::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(i) => {
+                    arg_names.push(i.ident.clone());
+                    i.mutability = None;
+                }
+                _ => {
+                    ctxt.error_spanned_by(
+                        arg,
+                        "pattern matching in task arguments is not yet supporteds",
+                    );
+                }
+            },
+        }
+    }
+
+    ctxt.check()?;
+
+    let name = f.sig.ident.clone();
+
+    let visibility = &f.vis;
+    f.sig.ident = format_ident!("task");
+    let impl_ty = if args.send {
+        quote!(impl ::core::future::Future + Send + 'static)
+    } else {
+        quote!(impl ::core::future::Future + 'static)
+    };
+
+    let attrs = &f.attrs;
+
+    let result = quote! {
+        #(#attrs)*
+        #visibility fn #name(#fargs) -> #embassy_path::executor::SpawnToken<#impl_ty> {
+            use #embassy_path::executor::raw::TaskStorage;
+            #f
+            type F = #impl_ty;
+            #[allow(clippy::declare_interior_mutable_const)]
+            const NEW_TASK: TaskStorage<F> = TaskStorage::new();
+            static POOL: [TaskStorage<F>; #pool_size] = [NEW_TASK; #pool_size];
+            unsafe { TaskStorage::spawn_pool(&POOL, move || task(#arg_names)) }
+        }
+    };
+
+    Ok(result)
+}