File size: 2,309 Bytes
1e92f2d | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 | use proc_macro::TokenStream;
use proc_macro2::TokenStream as TokenStream2;
use quote::quote;
use syn::{Data, DeriveInput, FieldsNamed, FieldsUnnamed, parse_macro_input};
use turbo_tasks_macros_shared::{generate_exhaustive_destructuring, match_expansion};
/// This macro generates the implementation of the `DeterministicHash` trait for
/// a given type.
///
/// This requires that every contained value also implement `DeterministicHash`.
pub fn derive_deterministic_hash(input: TokenStream) -> TokenStream {
let derive_input = parse_macro_input!(input as DeriveInput);
let ident = &derive_input.ident;
let match_hash = match_expansion(&derive_input, &hash_named, &hash_unnamed, &hash_unit);
let discriminant = match derive_input.data {
Data::Enum(_) => {
quote! {
turbo_tasks_hash::DeterministicHash::deterministic_hash(&std::mem::discriminant(self), __state__);
}
}
_ => quote! {},
};
quote! {
impl turbo_tasks_hash::DeterministicHash for #ident {
fn deterministic_hash<H: turbo_tasks_hash::DeterministicHasher>(&self, __state__: &mut H) {
#discriminant
#match_hash
}
}
}
.into()
}
/// Hashes a struct or enum variant with named fields (e.g. `struct Foo {
/// bar: u32 }`, `Foo::Bar { baz: u32 }`).
fn hash_named(_ident: TokenStream2, fields: &FieldsNamed) -> (TokenStream2, TokenStream2) {
let (captures, fields_idents) = generate_exhaustive_destructuring(fields.named.iter());
(
captures,
quote! {
{#(
#fields_idents.deterministic_hash(__state__);
)*}
},
)
}
/// Hashes a struct or enum variant with unnamed fields (e.g. `struct
/// Foo(u32)`, `Foo::Bar(u32)`).
fn hash_unnamed(_ident: TokenStream2, fields: &FieldsUnnamed) -> (TokenStream2, TokenStream2) {
let (captures, fields_idents) = generate_exhaustive_destructuring(fields.unnamed.iter());
(
captures,
quote! {
{#(
#fields_idents.deterministic_hash(__state__);
)*}
},
)
}
/// Hashes a unit struct or enum variant (e.g. `struct Foo;`, `Foo::Bar`).
fn hash_unit(_ident: TokenStream2) -> TokenStream2 {
quote! { { } }
}
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