1 // SPDX-License-Identifier: Apache-2.0 OR MIT
2
3 #[cfg(not(kernel))]
4 use proc_macro2 as proc_macro;
5
6 use proc_macro::{TokenStream, TokenTree};
7
pinned_drop(_args: TokenStream, input: TokenStream) -> TokenStream8 pub(crate) fn pinned_drop(_args: TokenStream, input: TokenStream) -> TokenStream {
9 let mut toks = input.into_iter().collect::<Vec<_>>();
10 assert!(!toks.is_empty());
11 // Ensure that we have an `impl` item.
12 assert!(matches!(&toks[0], TokenTree::Ident(i) if i.to_string() == "impl"));
13 // Ensure that we are implementing `PinnedDrop`.
14 let mut nesting: usize = 0;
15 let mut pinned_drop_idx = None;
16 for (i, tt) in toks.iter().enumerate() {
17 match tt {
18 TokenTree::Punct(p) if p.as_char() == '<' => {
19 nesting += 1;
20 }
21 TokenTree::Punct(p) if p.as_char() == '>' => {
22 nesting = nesting.checked_sub(1).unwrap();
23 continue;
24 }
25 _ => {}
26 }
27 if i >= 1 && nesting == 0 {
28 // Found the end of the generics, this should be `PinnedDrop`.
29 assert!(
30 matches!(tt, TokenTree::Ident(i) if i.to_string() == "PinnedDrop"),
31 "expected 'PinnedDrop', found: '{tt:?}'"
32 );
33 pinned_drop_idx = Some(i);
34 break;
35 }
36 }
37 let idx = pinned_drop_idx
38 .unwrap_or_else(|| panic!("Expected an `impl` block implementing `PinnedDrop`."));
39 // Fully qualify the `PinnedDrop`, as to avoid any tampering.
40 toks.splice(idx..idx, quote!(::pin_init::));
41 // Take the `{}` body and call the declarative macro.
42 if let Some(TokenTree::Group(last)) = toks.pop() {
43 let last = last.stream();
44 quote!(::pin_init::__pinned_drop! {
45 @impl_sig(#(#toks)*),
46 @impl_body(#last),
47 })
48 } else {
49 TokenStream::from_iter(toks)
50 }
51 }
52