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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
commit26a029d407be480d791972afb5975cf62c9360a6 (patch)
treef435a8308119effd964b339f76abb83a57c29483 /servo/components/to_shmem_derive/to_shmem.rs
parentInitial commit. (diff)
downloadfirefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz
firefox-26a029d407be480d791972afb5975cf62c9360a6.zip
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'servo/components/to_shmem_derive/to_shmem.rs')
-rw-r--r--servo/components/to_shmem_derive/to_shmem.rs78
1 files changed, 78 insertions, 0 deletions
diff --git a/servo/components/to_shmem_derive/to_shmem.rs b/servo/components/to_shmem_derive/to_shmem.rs
new file mode 100644
index 0000000000..157730c5a5
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+++ b/servo/components/to_shmem_derive/to_shmem.rs
@@ -0,0 +1,78 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use derive_common::cg;
+use proc_macro2::TokenStream;
+use syn;
+use synstructure::{BindStyle, Structure};
+
+pub fn derive(mut input: syn::DeriveInput) -> TokenStream {
+ let mut where_clause = input.generics.where_clause.take();
+ let attrs = cg::parse_input_attrs::<ShmemInputAttrs>(&input);
+ if !attrs.no_bounds {
+ for param in input.generics.type_params() {
+ cg::add_predicate(&mut where_clause, parse_quote!(#param: ::to_shmem::ToShmem));
+ }
+ }
+ for variant in Structure::new(&input).variants() {
+ for binding in variant.bindings() {
+ let attrs = cg::parse_field_attrs::<ShmemFieldAttrs>(&binding.ast());
+ if attrs.field_bound {
+ let ty = &binding.ast().ty;
+ cg::add_predicate(&mut where_clause, parse_quote!(#ty: ::to_shmem::ToShmem))
+ }
+ }
+ }
+
+ input.generics.where_clause = where_clause;
+
+ // Do all of the `to_shmem()?` calls before the `ManuallyDrop::into_inner()`
+ // calls, so that we don't drop a value in the shared memory buffer if one
+ // of the `to_shmem`s fails.
+ let match_body = cg::fmap2_match(
+ &input,
+ BindStyle::Ref,
+ |binding| {
+ quote! {
+ ::to_shmem::ToShmem::to_shmem(#binding, builder)?
+ }
+ },
+ |binding| {
+ Some(quote! {
+ ::std::mem::ManuallyDrop::into_inner(#binding)
+ })
+ },
+ );
+
+ let name = &input.ident;
+ let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
+
+ quote! {
+ impl #impl_generics ::to_shmem::ToShmem for #name #ty_generics #where_clause {
+ #[allow(unused_variables, unreachable_code)]
+ fn to_shmem(
+ &self,
+ builder: &mut ::to_shmem::SharedMemoryBuilder,
+ ) -> ::to_shmem::Result<Self> {
+ Ok(::std::mem::ManuallyDrop::new(
+ match *self {
+ #match_body
+ }
+ ))
+ }
+ }
+ }
+}
+
+#[derive(Default, FromDeriveInput)]
+#[darling(attributes(shmem), default)]
+pub struct ShmemInputAttrs {
+ pub no_bounds: bool,
+}
+
+#[derive(Default, FromField)]
+#[darling(attributes(shmem), default)]
+pub struct ShmemFieldAttrs {
+ pub field_bound: bool,
+}