trait_async/
parse.rs

1use proc_macro2::Span;
2use syn::parse::{Error, Parse, ParseStream, Result};
3use syn::{Attribute, ItemImpl, ItemTrait, Token};
4
5pub struct Nothing;
6
7impl Parse for Nothing {
8    fn parse(_input: ParseStream) -> Result<Self> {
9        Ok(Nothing)
10    }
11}
12
13pub enum Item {
14    Trait(ItemTrait),
15    Impl(ItemImpl),
16}
17
18impl Parse for Item {
19    fn parse(input: ParseStream) -> Result<Self> {
20        let attrs = input.call(Attribute::parse_outer)?;
21        let mut lookahead = input.lookahead1();
22        if lookahead.peek(Token![unsafe]) {
23            let ahead = input.fork();
24            ahead.parse::<Token![unsafe]>()?;
25            lookahead = ahead.lookahead1();
26        }
27        if lookahead.peek(Token![pub]) || lookahead.peek(Token![trait]) {
28            let mut item: ItemTrait = input.parse()?;
29            item.attrs = attrs;
30            Ok(Item::Trait(item))
31        } else if lookahead.peek(Token![impl]) {
32            let mut item: ItemImpl = input.parse()?;
33            if item.trait_.is_none() {
34                return Err(Error::new(Span::call_site(), "expected a trait impl"));
35            }
36            item.attrs = attrs;
37            Ok(Item::Impl(item))
38        } else {
39            Err(lookahead.error())
40        }
41    }
42}
trait_async/parse.rs

trait_async/
parse.rs
