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-rw-r--r--rust/macros/zeroable.rs72
1 files changed, 72 insertions, 0 deletions
diff --git a/rust/macros/zeroable.rs b/rust/macros/zeroable.rs
new file mode 100644
index 0000000000..0d605c46ab
--- /dev/null
+++ b/rust/macros/zeroable.rs
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use crate::helpers::{parse_generics, Generics};
+use proc_macro::{TokenStream, TokenTree};
+
+pub(crate) fn derive(input: TokenStream) -> TokenStream {
+ let (
+ Generics {
+ impl_generics,
+ ty_generics,
+ },
+ mut rest,
+ ) = parse_generics(input);
+ // This should be the body of the struct `{...}`.
+ let last = rest.pop();
+ // Now we insert `Zeroable` as a bound for every generic parameter in `impl_generics`.
+ let mut new_impl_generics = Vec::with_capacity(impl_generics.len());
+ // Are we inside of a generic where we want to add `Zeroable`?
+ let mut in_generic = !impl_generics.is_empty();
+ // Have we already inserted `Zeroable`?
+ let mut inserted = false;
+ // Level of `<>` nestings.
+ let mut nested = 0;
+ for tt in impl_generics {
+ match &tt {
+ // If we find a `,`, then we have finished a generic/constant/lifetime parameter.
+ TokenTree::Punct(p) if nested == 0 && p.as_char() == ',' => {
+ if in_generic && !inserted {
+ new_impl_generics.extend(quote! { : ::kernel::init::Zeroable });
+ }
+ in_generic = true;
+ inserted = false;
+ new_impl_generics.push(tt);
+ }
+ // If we find `'`, then we are entering a lifetime.
+ TokenTree::Punct(p) if nested == 0 && p.as_char() == '\'' => {
+ in_generic = false;
+ new_impl_generics.push(tt);
+ }
+ TokenTree::Punct(p) if nested == 0 && p.as_char() == ':' => {
+ new_impl_generics.push(tt);
+ if in_generic {
+ new_impl_generics.extend(quote! { ::kernel::init::Zeroable + });
+ inserted = true;
+ }
+ }
+ TokenTree::Punct(p) if p.as_char() == '<' => {
+ nested += 1;
+ new_impl_generics.push(tt);
+ }
+ TokenTree::Punct(p) if p.as_char() == '>' => {
+ assert!(nested > 0);
+ nested -= 1;
+ new_impl_generics.push(tt);
+ }
+ _ => new_impl_generics.push(tt),
+ }
+ }
+ assert_eq!(nested, 0);
+ if in_generic && !inserted {
+ new_impl_generics.extend(quote! { : ::kernel::init::Zeroable });
+ }
+ quote! {
+ ::kernel::__derive_zeroable!(
+ parse_input:
+ @sig(#(#rest)*),
+ @impl_generics(#(#new_impl_generics)*),
+ @ty_generics(#(#ty_generics)*),
+ @body(#last),
+ );
+ }
+}