#![doc(html_root_url = "https://docs.rs/tokio-macros/0.2.1")]
#![warn(
missing_debug_implementations,
missing_docs,
rust_2018_idioms,
unreachable_pub
)]
#![deny(intra_doc_link_resolution_failure)]
#![doc(test(
no_crate_inject,
attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables))
))]
//! Macros for use with Tokio
extern crate proc_macro;
use proc_macro::TokenStream;
use quote::quote;
enum Runtime {
Basic,
Threaded,
Auto,
}
/// Marks async function to be executed by selected runtime.
///
/// ## Options:
///
/// - `basic_scheduler` - All tasks are executed on the current thread.
/// - `threaded_scheduler` - Uses the multi-threaded scheduler. Used by default.
///
/// ## Function arguments:
///
/// Arguments are allowed for any functions aside from `main` which is special
///
/// ## Usage
///
/// ### Using default
///
/// ```rust
/// #[tokio::main]
/// async fn main() {
/// println!("Hello world");
/// }
/// ```
///
/// ### Select runtime
///
/// ```rust
/// #[tokio::main(basic_scheduler)]
/// async fn main() {
/// println!("Hello world");
/// }
/// ```
#[proc_macro_attribute]
#[cfg(not(test))] // Work around for rust-lang/rust#62127
pub fn main(args: TokenStream, item: TokenStream) -> TokenStream {
let input = syn::parse_macro_input!(item as syn::ItemFn);
let args = syn::parse_macro_input!(args as syn::AttributeArgs);
let ret = &input.sig.output;
let name = &input.sig.ident;
let inputs = &input.sig.inputs;
let body = &input.block;
let attrs = &input.attrs;
let vis = input.vis;
if input.sig.asyncness.is_none() {
let msg = "the async keyword is missing from the function declaration";
return syn::Error::new_spanned(input.sig.fn_token, msg)
.to_compile_error()
.into();
} else if name == "main" && !inputs.is_empty() {
let msg = "the main function cannot accept arguments";
return syn::Error::new_spanned(&input.sig.inputs, msg)
.to_compile_error()
.into();
}
let mut runtime = Runtime::Auto;
for arg in args {
if let syn::NestedMeta::Meta(syn::Meta::Path(path)) = arg {
let ident = path.get_ident();
if ident.is_none() {
let msg = "Must have specified ident";
return syn::Error::new_spanned(path, msg).to_compile_error().into();
}
match ident.unwrap().to_string().to_lowercase().as_str() {
"threaded_scheduler" => runtime = Runtime::Threaded,
"basic_scheduler" => runtime = Runtime::Basic,
name => {
let msg = format!("Unknown attribute {} is specified; expected `basic_scheduler` or `threaded_scheduler`", name);
return syn::Error::new_spanned(path, msg).to_compile_error().into();
}
}
}
}
let result = match runtime {
Runtime::Threaded | Runtime::Auto => quote! {
#(#attrs)*
#vis fn #name(#inputs) #ret {
tokio::runtime::Runtime::new().unwrap().block_on(async { #body })
}
},
Runtime::Basic => quote! {
#(#attrs)*
#vis fn #name(#inputs) #ret {
tokio::runtime::Builder::new()
.basic_scheduler()
.enable_all()
.build()
.unwrap()
.block_on(async { #body })
}
},
};
result.into()
}
/// Marks async function to be executed by runtime, suitable to test enviornment
///
/// ## Options:
///
/// - `basic_scheduler` - All tasks are executed on the current thread. Used by default.
/// - `threaded_scheduler` - Use multi-threaded scheduler.
///
/// ## Usage
///
/// ### Select runtime
///
/// ```no_run
/// #[tokio::test(threaded_scheduler)]
/// async fn my_test() {
/// assert!(true);
/// }
/// ```
///
/// ### Using default
///
/// ```no_run
/// #[tokio::test]
/// async fn my_test() {
/// assert!(true);
/// }
/// ```
#[proc_macro_attribute]
pub fn test(args: TokenStream, item: TokenStream) -> TokenStream {
let input = syn::parse_macro_input!(item as syn::ItemFn);
let args = syn::parse_macro_input!(args as syn::AttributeArgs);
let ret = &input.sig.output;
let name = &input.sig.ident;
let body = &input.block;
let attrs = &input.attrs;
let vis = input.vis;
for attr in attrs {
if attr.path.is_ident("test") {
let msg = "second test attribute is supplied";
return syn::Error::new_spanned(&attr, msg)
.to_compile_error()
.into();
}
}
if input.sig.asyncness.is_none() {
let msg = "the async keyword is missing from the function declaration";
return syn::Error::new_spanned(&input.sig.fn_token, msg)
.to_compile_error()
.into();
} else if !input.sig.inputs.is_empty() {
let msg = "the test function cannot accept arguments";
return syn::Error::new_spanned(&input.sig.inputs, msg)
.to_compile_error()
.into();
}
let mut runtime = Runtime::Auto;
for arg in args {
if let syn::NestedMeta::Meta(syn::Meta::Path(path)) = arg {
let ident = path.get_ident();
if ident.is_none() {
let msg = "Must have specified ident";
return syn::Error::new_spanned(path, msg).to_compile_error().into();
}
match ident.unwrap().to_string().to_lowercase().as_str() {
"threaded_scheduler" => runtime = Runtime::Threaded,
"basic_scheduler" => runtime = Runtime::Basic,
name => {
let msg = format!("Unknown attribute {} is specified; expected `basic_scheduler` or `threaded_scheduler`", name);
return syn::Error::new_spanned(path, msg).to_compile_error().into();
}
}
}
}
let result = match runtime {
Runtime::Threaded => quote! {
#[test]
#(#attrs)*
#vis fn #name() #ret {
tokio::runtime::Runtime::new().unwrap().block_on(async { #body })
}
},
Runtime::Basic | Runtime::Auto => quote! {
#[test]
#(#attrs)*
#vis fn #name() #ret {
tokio::runtime::Builder::new()
.basic_scheduler()
.enable_all()
.build()
.unwrap()
.block_on(async { #body })
}
},
};
result.into()
}