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#![doc(html_root_url = "https://docs.rs/tokio-macros/0.2.0-alpha.1")]
#![warn(missing_debug_implementations, unreachable_pub, rust_2018_idioms)]
#![doc(test(no_crate_inject, attr(deny(rust_2018_idioms))))]
//! Macros for use with Tokio
extern crate proc_macro;
use proc_macro::TokenStream;
use quote::{quote, quote_spanned};
use syn::spanned::Spanned;
/// 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
///#![feature(async_await)]
///
/// #[tokio::main(single_thread)]
/// async fn main() {
/// println!("Hello world");
/// }
/// ```
/// ### Using default
///
/// ```rust
///#![feature(async_await)]
///
/// #[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,
}
let input = syn::parse_macro_input!(item as syn::ItemFn);
let args = syn::parse_macro_input!(args as syn::AttributeArgs);
let ret = &input.decl.output;
let name = &input.ident;
let body = &input.block;
let attrs = &input.attrs;
if input.asyncness.is_none() {
let tokens = quote_spanned! { input.span() =>
compile_error!("the async keyword is missing from the function declaration");
};
return TokenStream::from(tokens);
} else if !input.decl.inputs.is_empty() {
let tokens = quote_spanned! { input.span() =>
compile_error!("the main function cannot accept arguments");
};
return TokenStream::from(tokens);
}
let mut runtime = RuntimeType::Multi;
for arg in args {
if let syn::NestedMeta::Meta(syn::Meta::Word(ident)) = arg {
match ident.to_string().to_lowercase().as_str() {
"multi_thread" => runtime = RuntimeType::Multi,
"single_thread" => runtime = RuntimeType::Single,
name => panic!("Unknown attribute {} is specified", name),
}
}
}
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 })
}
},
};
result.into()
}
/// Marks async function to be executed by runtime, suitable to test enviornment
///
/// Uses `current_thread` runtime.
///
/// # Examples
///
/// ```no_run
/// #![feature(async_await)]
///
/// #[tokio::test]
/// async fn my_test() {
/// assert!(true);
/// }
/// ```
#[proc_macro_attribute]
pub fn test(_attr: TokenStream, item: TokenStream) -> TokenStream {
let input = syn::parse_macro_input!(item as syn::ItemFn);
let ret = &input.decl.output;
let name = &input.ident;
let body = &input.block;
let attrs = &input.attrs;
for attr in attrs {
if attr.path.is_ident("test") {
let tokens = quote_spanned! { input.span() =>
compile_error!("second test attribute is supplied");
};
return TokenStream::from(tokens);
}
}
if input.asyncness.is_none() {
let tokens = quote_spanned! { input.span() =>
compile_error!("the async keyword is missing from the function declaration");
};
return TokenStream::from(tokens);
} else if !input.decl.inputs.is_empty() {
let tokens = quote_spanned! { input.span() =>
compile_error!("the test function cannot accept arguments");
};
return TokenStream::from(tokens);
}
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()
}
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