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/* 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;
use synstructure;
pub fn derive(mut input: syn::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::animated::ToAnimatedZero),
);
}
}
let to_body = synstructure::Structure::new(&input).each_variant(|variant| {
let attrs = cg::parse_variant_attrs_from_ast::<AnimationVariantAttrs>(&variant.ast());
if attrs.error {
return Some(quote! { Err(()) });
}
let (mapped, mapped_bindings) = cg::value(variant, "mapped");
let bindings_pairs = variant.bindings().iter().zip(mapped_bindings);
let mut computations = quote!();
computations.append_all(bindings_pairs.map(|(binding, mapped_binding)| {
let field_attrs = cg::parse_field_attrs::<AnimationFieldAttrs>(&binding.ast());
if field_attrs.constant {
quote! {
let #mapped_binding = std::clone::Clone::clone(#binding);
}
} else {
quote! {
let #mapped_binding =
crate::values::animated::ToAnimatedZero::to_animated_zero(#binding)?;
}
}
}));
computations.append_all(quote! { Ok(#mapped) });
Some(computations)
});
input.generics.where_clause = where_clause;
let name = &input.ident;
let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
quote! {
impl #impl_generics crate::values::animated::ToAnimatedZero for #name #ty_generics #where_clause {
#[allow(unused_variables)]
#[inline]
fn to_animated_zero(&self) -> Result<Self, ()> {
match *self {
#to_body
}
}
}
}
}
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