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-rw-r--r--rust/macros/pinned_drop.rs49
1 files changed, 49 insertions, 0 deletions
diff --git a/rust/macros/pinned_drop.rs b/rust/macros/pinned_drop.rs
new file mode 100644
index 000000000000..88fb72b20660
--- /dev/null
+++ b/rust/macros/pinned_drop.rs
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use proc_macro::{TokenStream, TokenTree};
+
+pub(crate) fn pinned_drop(_args: TokenStream, input: TokenStream) -> TokenStream {
+ let mut toks = input.into_iter().collect::<Vec<_>>();
+ assert!(!toks.is_empty());
+ // Ensure that we have an `impl` item.
+ assert!(matches!(&toks[0], TokenTree::Ident(i) if i.to_string() == "impl"));
+ // Ensure that we are implementing `PinnedDrop`.
+ let mut nesting: usize = 0;
+ let mut pinned_drop_idx = None;
+ for (i, tt) in toks.iter().enumerate() {
+ match tt {
+ TokenTree::Punct(p) if p.as_char() == '<' => {
+ nesting += 1;
+ }
+ TokenTree::Punct(p) if p.as_char() == '>' => {
+ nesting = nesting.checked_sub(1).unwrap();
+ continue;
+ }
+ _ => {}
+ }
+ if i >= 1 && nesting == 0 {
+ // Found the end of the generics, this should be `PinnedDrop`.
+ assert!(
+ matches!(tt, TokenTree::Ident(i) if i.to_string() == "PinnedDrop"),
+ "expected 'PinnedDrop', found: '{:?}'",
+ tt
+ );
+ pinned_drop_idx = Some(i);
+ break;
+ }
+ }
+ let idx = pinned_drop_idx
+ .unwrap_or_else(|| panic!("Expected an `impl` block implementing `PinnedDrop`."));
+ // Fully qualify the `PinnedDrop`, as to avoid any tampering.
+ toks.splice(idx..idx, quote!(::kernel::init::));
+ // Take the `{}` body and call the declarative macro.
+ if let Some(TokenTree::Group(last)) = toks.pop() {
+ let last = last.stream();
+ quote!(::kernel::__pinned_drop! {
+ @impl_sig(#(#toks)*),
+ @impl_body(#last),
+ })
+ } else {
+ TokenStream::from_iter(toks)
+ }
+}