servo/components/style_derive/to_animated_value.rs

/* 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 proc_macro2::TokenStream;
use syn::DeriveInput;
use synstructure::BindStyle;
use to_computed_value;

pub fn derive(input: DeriveInput) -> TokenStream {
    let trait_impl = |from_body, to_body| {
        quote! {
             #[inline]
             fn from_animated_value(animated: Self::AnimatedValue) -> Self {
                 match animated {
                     #from_body
                 }
             }

             #[inline]
             fn to_animated_value(self) -> Self::AnimatedValue {
                 match self {
                     #to_body
                 }
             }
        }
    };

    // TODO(emilio): Consider optimizing away non-generic cases as well?
    let non_generic_implementation = || None;

    to_computed_value::derive_to_value(
        input,
        parse_quote!(crate::values::animated::ToAnimatedValue),
        parse_quote!(AnimatedValue),
        BindStyle::Move,
        |_| false,
        |binding| quote!(crate::values::animated::ToAnimatedValue::from_animated_value(#binding)),
        |binding| quote!(crate::values::animated::ToAnimatedValue::to_animated_value(#binding)),
        trait_impl,
        non_generic_implementation,
    )
}