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Implement #[animate(fallback)] for #[derive(Animate)]

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This allows us to derive the Animate trait, providing a fallback function
for when the 2 values aren't similar.
This commit is contained in:
Anthony Ramine 2017-08-26 16:25:28 +02:00
parent 3751fe9fdc
commit 4a4bf89575
7 changed files with 99 additions and 121 deletions
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35
components/style_derive/animate.rs
View file

@ -3,21 +3,22 @@
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use cg;
use quote;
use syn;
use quote::Tokens;
use syn::{DeriveInput, Path};
pub fn derive(input: syn::DeriveInput) -> quote::Tokens {
pub fn derive(input: DeriveInput) -> Tokens {
let name = &input.ident;
let trait_path = &["values", "animated", "Animate"];
let (impl_generics, ty_generics, mut where_clause) =
cg::trait_parts(&input, trait_path);
let input_attrs = cg::parse_input_attrs::<AnimateInputAttrs>(&input);
let variants = cg::variants(&input);
let mut match_body = quote!();
let mut append_error_clause = variants.len() > 1;
match_body.append_all(variants.iter().flat_map(|variant| {
let attrs = cg::parse_variant_attrs::<AnimateAttrs>(variant);
if attrs.error {
let variant_attrs = cg::parse_variant_attrs::<AnimationVariantAttrs>(variant);
if variant_attrs.error {
append_error_clause = true;
return None;
}
@ -28,7 +29,7 @@ pub fn derive(input: syn::DeriveInput) -> quote::Tokens {
let mut computations = quote!();
let iter = result_info.iter().zip(this_info.iter().zip(&other_info));
computations.append_all(iter.map(|(result, (this, other))| {
let field_attrs = cg::parse_field_attrs::<AnimateFieldAttrs>(&result.field);
let field_attrs = cg::parse_field_attrs::<AnimationFieldAttrs>(&result.field);
if field_attrs.constant {
if cg::is_parameterized(&result.field.ty, where_clause.params, None) {
where_clause.inner.predicates.push(cg::where_predicate(
@ -65,7 +66,13 @@ pub fn derive(input: syn::DeriveInput) -> quote::Tokens {
}));
if append_error_clause {
match_body = quote! { #match_body, _ => Err(()), };
if let Some(fallback) = input_attrs.fallback {
match_body.append(quote! {
(this, other) => #fallback(this, other, procedure)
});
} else {
match_body.append(quote! { _ => Err(()) });
}
}
quote! {
@ -85,14 +92,20 @@ pub fn derive(input: syn::DeriveInput) -> quote::Tokens {
}
}
#[derive(Default, FromVariant)]
#[darling(attributes(animate), default)]
#[derive(Default, FromDeriveInput)]
struct AnimateInputAttrs {
fallback: Option<Path>,
}
#[darling(attributes(animation), default)]
pub struct AnimateAttrs {
#[derive(Default, FromVariant)]
pub struct AnimationVariantAttrs {
pub error: bool,
}
#[derive(Default, FromField)]
#[darling(attributes(animation), default)]
pub struct AnimateFieldAttrs {
#[derive(Default, FromField)]
pub struct AnimationFieldAttrs {
pub constant: bool,
}