зеркало из https://github.com/mozilla/gecko-dev.git
130 строки
4.1 KiB
Rust
130 строки
4.1 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 darling::util::IdentList;
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use quote::Tokens;
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use syn::{DeriveInput, Path};
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use synstructure::{Structure, VariantInfo};
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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::animated::Animate),
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);
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}
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}
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input.generics.where_clause = where_clause;
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let s = 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 arm = match derive_variant_arm(variant) {
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Ok(arm) => arm,
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Err(()) => {
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append_error_clause = true;
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return body;
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}
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};
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quote! { #body #arm }
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});
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if append_error_clause {
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let input_attrs = cg::parse_input_attrs::<AnimateInputAttrs>(&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, 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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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::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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fn derive_variant_arm(variant: &VariantInfo) -> Result<Tokens, ()> {
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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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return Err(());
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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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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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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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Ok(quote! {
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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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#[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, FromDeriveInput)]
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pub struct AnimationInputAttrs {
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pub no_bound: Option<IdentList>,
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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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// Only here because of structs, where the struct definition acts as a
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// variant itself.
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pub no_bound: Option<IdentList>,
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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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