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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
commit | 26a029d407be480d791972afb5975cf62c9360a6 (patch) | |
tree | f435a8308119effd964b339f76abb83a57c29483 /servo/components/style_derive/compute_squared_distance.rs | |
parent | Initial commit. (diff) | |
download | firefox-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.rs | 125 |
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 new file mode 100644 index 0000000000..022ab115ee --- /dev/null +++ b/servo/components/style_derive/compute_squared_distance.rs @@ -0,0 +1,125 @@ +/* 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(¶m.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, +} |