forked from mirrors/gecko-dev
68b65ee807
Most of types just derive it using proc_macro directly. Some of value types need manual impl. In my current plan, this new trait will be used in bug 1434130 to expose values as well. MozReview-Commit-ID: LI7fy45VkRw --HG-- extra : rebase_source : a765e43b0c615e5f47bddb90ba6fa24bfc06959e extra : source : 60812c1b190d90602bc6d49477fe1f558a53cd51
108 lines
3.8 KiB
Rust
108 lines
3.8 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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use animate::{AnimationInputAttrs, AnimationVariantAttrs};
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use cg;
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use quote::Tokens;
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use syn::{DeriveInput, Path};
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use synstructure;
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pub fn derive(mut input: DeriveInput) -> Tokens {
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let animation_input_attrs = cg::parse_input_attrs::<AnimationInputAttrs>(&input);
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let no_bound = animation_input_attrs.no_bound.unwrap_or_default();
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let mut where_clause = input.generics.where_clause.take();
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for param in input.generics.type_params() {
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if !no_bound.contains(¶m.ident) {
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cg::add_predicate(
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&mut where_clause,
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parse_quote!(#param: ::values::distance::ComputeSquaredDistance),
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);
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}
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}
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let (mut match_body, append_error_clause) = {
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let s = synstructure::Structure::new(&input);
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let mut append_error_clause = s.variants().len() > 1;
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let match_body = s.variants().iter().fold(quote!(), |body, variant| {
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let attrs = cg::parse_variant_attrs_from_ast::<AnimationVariantAttrs>(&variant.ast());
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if attrs.error {
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append_error_clause = true;
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return body;
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}
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let (this_pattern, this_info) = cg::ref_pattern(&variant, "this");
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let (other_pattern, other_info) = cg::ref_pattern(&variant, "other");
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let sum = if this_info.is_empty() {
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quote! { ::values::distance::SquaredDistance::from_sqrt(0.) }
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} else {
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let mut sum = quote!();
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sum.append_separated(this_info.iter().zip(&other_info).map(|(this, other)| {
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let field_attrs = cg::parse_field_attrs::<DistanceFieldAttrs>(&this.ast());
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if field_attrs.field_bound {
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let ty = &this.ast().ty;
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cg::add_predicate(
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&mut where_clause,
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parse_quote!(#ty: ::values::distance::ComputeSquaredDistance),
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);
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}
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quote! {
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::values::distance::ComputeSquaredDistance::compute_squared_distance(#this, #other)?
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}
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}), quote!(+));
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sum
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};
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quote! {
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#body
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(&#this_pattern, &#other_pattern) => {
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Ok(#sum)
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}
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}
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});
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(match_body, append_error_clause)
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};
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input.generics.where_clause = where_clause;
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if append_error_clause {
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let input_attrs = cg::parse_input_attrs::<DistanceInputAttrs>(&input);
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if let Some(fallback) = input_attrs.fallback {
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match_body.append_all(quote! {
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(this, other) => #fallback(this, other)
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});
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} else {
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match_body.append_all(quote! { _ => Err(()) });
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}
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}
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let name = &input.ident;
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let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
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quote! {
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impl #impl_generics ::values::distance::ComputeSquaredDistance for #name #ty_generics #where_clause {
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#[allow(unused_variables, unused_imports)]
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#[inline]
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fn compute_squared_distance(
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&self,
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other: &Self,
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) -> Result<::values::distance::SquaredDistance, ()> {
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match (self, other) {
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#match_body
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}
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}
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}
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}
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}
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#[darling(attributes(distance), default)]
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#[derive(Default, FromDeriveInput)]
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struct DistanceInputAttrs {
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fallback: Option<Path>,
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}
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#[darling(attributes(distance), default)]
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#[derive(Default, FromField)]
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struct DistanceFieldAttrs {
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field_bound: bool,
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}
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