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7c50db26c0
Source-Repo: https://github.com/servo/servo Source-Revision: a266e96d28b7960b4fb0b236c3e8e93cf70f09b0 --HG-- extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear extra : subtree_revision : 9e09cb393bbddd26e1714c54fd176de8d64168f5
79 lines
2.7 KiB
Rust
79 lines
2.7 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::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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pub fn derive(input: DeriveInput) -> Tokens {
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let name = &input.ident;
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let trait_path = &["values", "distance", "ComputeSquaredDistance"];
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let (impl_generics, ty_generics, mut where_clause) =
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cg::trait_parts(&input, trait_path);
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let input_attrs = cg::parse_input_attrs::<DistanceInputAttrs>(&input);
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let variants = cg::variants(&input);
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let mut match_body = quote!();
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let mut append_error_clause = variants.len() > 1;
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match_body.append_all(variants.iter().map(|variant| {
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let attrs = cg::parse_variant_attrs::<AnimationVariantAttrs>(variant);
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if attrs.error {
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append_error_clause = true;
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return None;
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}
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let name = cg::variant_ctor(&input, variant);
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let (this_pattern, this_info) = cg::ref_pattern(&name, &variant, "this");
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let (other_pattern, other_info) = cg::ref_pattern(&name, &variant, "other");
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let sum = if this_info.is_empty() {
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quote! { ::values::distance::SquaredDistance::Value(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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where_clause.add_trait_bound(&this.field.ty);
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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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}), "+");
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sum
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};
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Some(quote! {
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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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if append_error_clause {
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if let Some(fallback) = input_attrs.fallback {
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match_body.append(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(quote! { _ => Err(()) });
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}
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}
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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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