#![doc(html_root_url = "https://docs.rs/tokio-macros/0.2.0-alpha.5")]
#![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;
/// Marks async function to be executed by selected runtime.
///
/// ## Options:
///
/// - `single_thread` - Uses `current_thread`.
/// - `multi_thread` - Uses multi-threaded runtime. Used by default.
///
/// ## Usage
///
/// ### Select runtime
///
/// ```rust
/// #[tokio::main(single_thread)]
/// async fn main() {
/// println!("Hello world");
/// }
/// ```
/// ### Using default
///
/// ```rust
/// #[tokio::main]
/// 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 {
enum RuntimeType {
Single,
Multi,
Auto,
}
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;
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 main function cannot accept arguments";
return syn::Error::new_spanned(&input.sig.inputs, msg)
.to_compile_error()
.into();
}
let mut runtime = RuntimeType::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() {
"multi_thread" => runtime = RuntimeType::Multi,
"single_thread" => runtime = RuntimeType::Single,
name => {
let msg = format!("Unknown attribute {} is specified", name);
return syn::Error::new_spanned(path, msg).to_compile_error().into();
}
}
}
}
let result = match runtime {
RuntimeType::Multi => quote! {
#(#attrs)*
fn #name() #ret {
let mut rt = tokio::runtime::Runtime::new().unwrap();
rt.block_on(async { #body })
}
},
RuntimeType::Single => quote! {
#(#attrs)*
fn #name() #ret {
let mut rt = tokio::runtime::current_thread::Runtime::new().unwrap();
rt.block_on(async { #body })
}
},
RuntimeType::Auto => quote! {
#(#attrs)*
fn #name() #ret {
let mut rt = tokio::runtime::__main::Runtime::new().unwrap();
rt.block_on(async { #body })
}
},
};
result.into()
}
/// Marks async function to be executed by runtime, suitable to test enviornment
///
/// Uses `current_thread` runtime.
///
/// # Examples
///
/// ```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 _ = syn::parse_macro_input!(args as syn::parse::Nothing);
let ret = &input.sig.output;
let name = &input.sig.ident;
let body = &input.block;
let attrs = &input.attrs;
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 result = quote! {
#[test]
#(#attrs)*
fn #name() #ret {
let mut rt = tokio::runtime::current_thread::Runtime::new().unwrap();
rt.block_on(async { #body })
}
};
result.into()
}