mirror of
https://github.com/servo/servo.git
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112 lines
3.9 KiB
Rust
112 lines
3.9 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 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(input: DeriveInput) -> Tokens {
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let name = &input.ident;
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let trait_path = parse_quote!(values::animated::Animate);
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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::<AnimateInputAttrs>(&input);
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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 mut match_body = s.variants().iter().fold(quote!(), |body, variant| {
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let variant_attrs = cg::parse_variant_attrs::<AnimationVariantAttrs>(&variant.ast());
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if variant_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 (result_value, result_info) = cg::value(&variant, "result");
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let mut computations = quote!();
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let iter = result_info.iter().zip(this_info.iter().zip(&other_info));
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computations.append_all(iter.map(|(result, (this, other))| {
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let field_attrs = cg::parse_field_attrs::<AnimationFieldAttrs>(&result.ast());
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if field_attrs.constant {
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if cg::is_parameterized(&result.ast().ty, &where_clause.params, None) {
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where_clause.add_predicate(cg::where_predicate(
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result.ast().ty.clone(),
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&parse_quote!(std::cmp::PartialEq),
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None,
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));
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where_clause.add_predicate(cg::where_predicate(
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result.ast().ty.clone(),
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&parse_quote!(std::clone::Clone),
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None,
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));
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}
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quote! {
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if #this != #other {
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return Err(());
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}
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let #result = ::std::clone::Clone::clone(#this);
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}
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} else {
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where_clause.add_trait_bound(&result.ast().ty);
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quote! {
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let #result =
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::values::animated::Animate::animate(#this, #other, procedure)?;
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}
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}
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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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#computations
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Ok(#result_value)
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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_all(quote! {
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(this, other) => #fallback(this, other, procedure)
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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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quote! {
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impl #impl_generics ::values::animated::Animate 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 animate(
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&self,
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other: &Self,
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procedure: ::values::animated::Procedure,
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) -> Result<Self, ()> {
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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(animate), default)]
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#[derive(Default, FromDeriveInput)]
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struct AnimateInputAttrs {
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fallback: Option<Path>,
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}
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#[darling(attributes(animation), default)]
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#[derive(Default, FromVariant)]
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pub struct AnimationVariantAttrs {
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pub error: bool,
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}
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#[darling(attributes(animation), default)]
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#[derive(Default, FromField)]
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pub struct AnimationFieldAttrs {
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pub constant: bool,
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}
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