// 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) } }