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use proc_macro2::Span;
use syn::parse::{Error, Parse, ParseStream, Result};
use syn::Token;
#[derive(Copy, Clone)]
pub struct Args {
pub local: bool,
}
mod kw {
syn::custom_keyword!(Send);
}
impl Parse for Args {
fn parse(input: ParseStream) -> Result<Self> {
match try_parse(input) {
Ok(args) if input.is_empty() => Ok(args),
_ => Err(error()),
}
}
}
fn try_parse(input: ParseStream) -> Result<Args> {
if input.peek(Token![?]) {
input.parse::<Token![?]>()?;
input.parse::<kw::Send>()?;
Ok(Args { local: true })
} else {
Ok(Args { local: false })
}
}
fn error() -> Error {
let msg = "expected #[async_trait] or #[async_trait(?Send)]";
Error::new(Span::call_site(), msg)
}