129 lines
3.9 KiB
Rust
129 lines
3.9 KiB
Rust
use proc_macro2::{self, Ident};
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use quote::quote;
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use syn::{self, parse_quote};
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struct Attributes {
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ignore: bool,
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project: Option<Ident>,
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}
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fn parse_attributes(field: &syn::Field) -> Attributes {
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let mut attrs = Attributes { ignore: false, project: None };
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for attr in &field.attrs {
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let meta = &attr.meta;
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if !meta.path().is_ident("stable_hasher") {
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continue;
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}
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let mut any_attr = false;
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let _ = attr.parse_nested_meta(|nested| {
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if nested.path.is_ident("ignore") {
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attrs.ignore = true;
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any_attr = true;
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}
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if nested.path.is_ident("project") {
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let _ = nested.parse_nested_meta(|meta| {
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if attrs.project.is_none() {
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attrs.project = meta.path.get_ident().cloned();
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}
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any_attr = true;
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Ok(())
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});
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}
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Ok(())
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});
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if !any_attr {
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panic!("error parsing stable_hasher");
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}
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}
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attrs
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}
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pub fn hash_stable_generic_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
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let generic: syn::GenericParam = parse_quote!(__CTX);
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s.add_bounds(synstructure::AddBounds::Generics);
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s.add_impl_generic(generic);
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s.add_where_predicate(parse_quote! { __CTX: crate::HashStableContext });
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let body = s.each(|bi| {
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let attrs = parse_attributes(bi.ast());
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if attrs.ignore {
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quote! {}
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} else if let Some(project) = attrs.project {
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quote! {
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(&#bi.#project).hash_stable(__hcx, __hasher);
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}
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} else {
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quote! {
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#bi.hash_stable(__hcx, __hasher);
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}
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}
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});
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let discriminant = match s.ast().data {
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syn::Data::Enum(_) => quote! {
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::std::mem::discriminant(self).hash_stable(__hcx, __hasher);
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},
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syn::Data::Struct(_) => quote! {},
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syn::Data::Union(_) => panic!("cannot derive on union"),
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};
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s.bound_impl(
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quote!(::rustc_data_structures::stable_hasher::HashStable<__CTX>),
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quote! {
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#[inline]
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fn hash_stable(
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&self,
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__hcx: &mut __CTX,
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__hasher: &mut ::rustc_data_structures::stable_hasher::StableHasher) {
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#discriminant
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match *self { #body }
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}
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},
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)
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}
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pub fn hash_stable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
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let generic: syn::GenericParam = parse_quote!('__ctx);
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s.add_bounds(synstructure::AddBounds::Generics);
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s.add_impl_generic(generic);
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let body = s.each(|bi| {
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let attrs = parse_attributes(bi.ast());
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if attrs.ignore {
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quote! {}
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} else if let Some(project) = attrs.project {
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quote! {
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(&#bi.#project).hash_stable(__hcx, __hasher);
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}
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} else {
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quote! {
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#bi.hash_stable(__hcx, __hasher);
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}
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}
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});
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let discriminant = match s.ast().data {
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syn::Data::Enum(_) => quote! {
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::std::mem::discriminant(self).hash_stable(__hcx, __hasher);
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},
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syn::Data::Struct(_) => quote! {},
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syn::Data::Union(_) => panic!("cannot derive on union"),
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};
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s.bound_impl(
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quote!(
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::rustc_data_structures::stable_hasher::HashStable<
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::rustc_query_system::ich::StableHashingContext<'__ctx>,
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>
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),
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quote! {
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#[inline]
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fn hash_stable(
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&self,
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__hcx: &mut ::rustc_query_system::ich::StableHashingContext<'__ctx>,
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__hasher: &mut ::rustc_data_structures::stable_hasher::StableHasher) {
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#discriminant
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match *self { #body }
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}
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},
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)
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}
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