diff --git a/embassy-macros/README.md b/embassy-macros/README.md new file mode 100644 index 000000000..d1d6f4cc4 --- /dev/null +++ b/embassy-macros/README.md @@ -0,0 +1,21 @@ +# embassy-macros + +An [Embassy](https://embassy.dev) project. + +Macros for creating the main entry point and tasks that can be spawned by `embassy-executor`. + +NOTE: The macros are re-exported by the `embassy-executor` crate which should be used instead of adding a direct dependency on the `embassy-macros` crate. + +## Minimum supported Rust version (MSRV) + +The `task` and `main` macros require the type alias impl trait (TAIT) nightly feature in order to compile. + +## License + +This work is licensed under either of + +- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or + ) +- MIT license ([LICENSE-MIT](LICENSE-MIT) or ) + +at your option. diff --git a/embassy-macros/src/lib.rs b/embassy-macros/src/lib.rs index ec8498f9f..f5df2a269 100644 --- a/embassy-macros/src/lib.rs +++ b/embassy-macros/src/lib.rs @@ -1,3 +1,4 @@ +#![doc = include_str!("../README.md")] extern crate proc_macro; use proc_macro::TokenStream; @@ -6,6 +7,36 @@ mod macros; mod util; use macros::*; +/// Declares an async task that can be run by `embassy-executor`. The optional `pool_size` parameter can be used to specify how +/// many concurrent tasks can be spawned (default is 1) for the function. +/// +/// +/// The following restrictions apply: +/// +/// * The function must be declared `async`. +/// * The function must not use generics. +/// * The optional `pool_size` attribute must be 1 or greater. +/// +/// +/// ## Examples +/// +/// Declaring a task taking no arguments: +/// +/// ``` rust +/// #[embassy_executor::task] +/// async fn mytask() { +/// // Function body +/// } +/// ``` +/// +/// Declaring a task with a given pool size: +/// +/// ``` rust +/// #[embassy_executor::task(pool_size = 4)] +/// async fn mytask() { +/// // Function body +/// } +/// ``` #[proc_macro_attribute] pub fn task(args: TokenStream, item: TokenStream) -> TokenStream { let args = syn::parse_macro_input!(args as syn::AttributeArgs); @@ -14,6 +45,24 @@ pub fn task(args: TokenStream, item: TokenStream) -> TokenStream { task::run(args, f).unwrap_or_else(|x| x).into() } +/// Creates a new `executor` instance and declares an application entry point spawning the corresponding function body as an async task. +/// +/// The following restrictions apply: +/// +/// * The function must accept exactly 1 parameter, an `embassy_executor::Spawner` handle that it can use to spawn additional tasks. +/// * The function must be declared `async`. +/// * The function must not use generics. +/// * Only a single `main` task may be declared. +/// +/// ## Examples +/// Spawning a task: +/// +/// ``` rust +/// #[embassy_executor::main] +/// async fn main(_s: embassy_executor::Spawner) { +/// // Function body +/// } +/// ``` #[proc_macro_attribute] pub fn main(args: TokenStream, item: TokenStream) -> TokenStream { let args = syn::parse_macro_input!(args as syn::AttributeArgs);