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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/style_derive/compute_squared_distance.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/style_derive/compute_squared_distance.rs')
-rw-r--r--servo/components/style_derive/compute_squared_distance.rs125
1 files changed, 125 insertions, 0 deletions
diff --git a/servo/components/style_derive/compute_squared_distance.rs b/servo/components/style_derive/compute_squared_distance.rs
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+++ b/servo/components/style_derive/compute_squared_distance.rs
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+/* 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 crate::animate::{AnimationFieldAttrs, AnimationInputAttrs, AnimationVariantAttrs};
+use derive_common::cg;
+use proc_macro2::TokenStream;
+use quote::TokenStreamExt;
+use syn::{DeriveInput, WhereClause};
+use synstructure;
+
+pub fn derive(mut input: DeriveInput) -> TokenStream {
+ let animation_input_attrs = cg::parse_input_attrs::<AnimationInputAttrs>(&input);
+ let no_bound = animation_input_attrs.no_bound.unwrap_or_default();
+ let mut where_clause = input.generics.where_clause.take();
+ for param in input.generics.type_params() {
+ if !no_bound.iter().any(|name| name.is_ident(&param.ident)) {
+ cg::add_predicate(
+ &mut where_clause,
+ parse_quote!(#param: crate::values::distance::ComputeSquaredDistance),
+ );
+ }
+ }
+
+ let (mut match_body, needs_catchall_branch) = {
+ let s = synstructure::Structure::new(&input);
+ let needs_catchall_branch = s.variants().len() > 1;
+
+ let match_body = s.variants().iter().fold(quote!(), |body, variant| {
+ let arm = derive_variant_arm(variant, &mut where_clause);
+ quote! { #body #arm }
+ });
+
+ (match_body, needs_catchall_branch)
+ };
+
+ input.generics.where_clause = where_clause;
+
+ if needs_catchall_branch {
+ // This ideally shouldn't be needed, but see:
+ // https://github.com/rust-lang/rust/issues/68867
+ match_body.append_all(quote! { _ => unsafe { debug_unreachable!() } });
+ }
+
+ let name = &input.ident;
+ let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
+
+ quote! {
+ impl #impl_generics crate::values::distance::ComputeSquaredDistance for #name #ty_generics #where_clause {
+ #[allow(unused_variables, unused_imports)]
+ #[inline]
+ fn compute_squared_distance(
+ &self,
+ other: &Self,
+ ) -> Result<crate::values::distance::SquaredDistance, ()> {
+ if std::mem::discriminant(self) != std::mem::discriminant(other) {
+ return Err(());
+ }
+ match (self, other) {
+ #match_body
+ }
+ }
+ }
+ }
+}
+
+fn derive_variant_arm(
+ variant: &synstructure::VariantInfo,
+ mut where_clause: &mut Option<WhereClause>,
+) -> TokenStream {
+ let variant_attrs = cg::parse_variant_attrs_from_ast::<AnimationVariantAttrs>(&variant.ast());
+ let (this_pattern, this_info) = cg::ref_pattern(&variant, "this");
+ let (other_pattern, other_info) = cg::ref_pattern(&variant, "other");
+
+ if variant_attrs.error {
+ return quote! {
+ (&#this_pattern, &#other_pattern) => Err(()),
+ };
+ }
+
+ let sum = if this_info.is_empty() {
+ quote! { crate::values::distance::SquaredDistance::from_sqrt(0.) }
+ } else {
+ let mut sum = quote!();
+ sum.append_separated(this_info.iter().zip(&other_info).map(|(this, other)| {
+ let field_attrs = cg::parse_field_attrs::<DistanceFieldAttrs>(&this.ast());
+ if field_attrs.field_bound {
+ let ty = &this.ast().ty;
+ cg::add_predicate(
+ &mut where_clause,
+ parse_quote!(#ty: crate::values::distance::ComputeSquaredDistance),
+ );
+ }
+
+ let animation_field_attrs =
+ cg::parse_field_attrs::<AnimationFieldAttrs>(&this.ast());
+
+ if animation_field_attrs.constant {
+ quote! {
+ {
+ if #this != #other {
+ return Err(());
+ }
+ crate::values::distance::SquaredDistance::from_sqrt(0.)
+ }
+ }
+ } else {
+ quote! {
+ crate::values::distance::ComputeSquaredDistance::compute_squared_distance(#this, #other)?
+ }
+ }
+ }), quote!(+));
+ sum
+ };
+
+ return quote! {
+ (&#this_pattern, &#other_pattern) => Ok(#sum),
+ };
+}
+
+#[derive(Default, FromField)]
+#[darling(attributes(distance), default)]
+struct DistanceFieldAttrs {
+ field_bound: bool,
+}