1use proc_macro2::Span;
2use syn::parse::{Error, Parse, ParseStream, Result};
3use syn::Token;
4
5#[derive(Copy, Clone)]
6pub struct Args {
7 pub local: bool,
8}
9
10mod kw {
11 syn::custom_keyword!(Send);
12}
13
14impl Parse for Args {
15 fn parse(input: ParseStream) -> Result<Self> {
16 match try_parse(input) {
17 Ok(args: Args) if input.is_empty() => Ok(args),
18 _ => Err(error()),
19 }
20 }
21}
22
23fn try_parse(input: ParseStream) -> Result<Args> {
24 if input.peek(Token![?]) {
25 input.parse::<Token![?]>()?;
26 input.parse::<kw::Send>()?;
27 Ok(Args { local: true })
28 } else {
29 Ok(Args { local: false })
30 }
31}
32
33fn error() -> Error {
34 let msg: &'static str = "expected #[async_trait] or #[async_trait(?Send)]";
35 Error::new(Span::call_site(), message:msg)
36}
37