pin_init_internal/
pinned_drop.rs

1// SPDX-License-Identifier: Apache-2.0 OR MIT
2
3#[cfg(not(kernel))]
4use proc_macro2 as proc_macro;
5
6use proc_macro::{TokenStream, TokenTree};
7
8pub(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}
pin_init_internal/pinned_drop.rs

pin_init_internal/
pinned_drop.rs
