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7fe7b2ffb1
Most of types just derive it using proc_macro directly. Some of value types need manual impl. In my current plan, this new trait will be used in bug 1434130 to expose values as well. Bug: 1455576 Reviewed-by: emilio MozReview-Commit-ID: LI7fy45VkRw
68 lines
2.4 KiB
Rust
68 lines
2.4 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::{Data, DeriveInput, Fields};
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use to_css::{CssFieldAttrs, CssInputAttrs, CssVariantAttrs};
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pub fn derive(mut input: DeriveInput) -> Tokens {
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let attrs = cg::parse_input_attrs::<CssInputAttrs>(&input);
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let mut types_value = quote!(0);
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// If the whole value is wrapped in a function, value types of its
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// fields should not be propagated.
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if attrs.function.is_none() {
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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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cg::add_predicate(
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&mut where_clause,
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parse_quote!(#param: ::style_traits::SpecifiedValueInfo),
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);
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}
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input.generics.where_clause = where_clause;
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match input.data {
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Data::Enum(ref e) => {
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for v in e.variants.iter() {
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let attrs = cg::parse_variant_attrs::<CssVariantAttrs>(&v);
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if attrs.function.is_none() {
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derive_struct_fields(&v.fields, &mut types_value);
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}
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}
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}
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Data::Struct(ref s) => {
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derive_struct_fields(&s.fields, &mut types_value)
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}
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Data::Union(_) => unreachable!("union is not supported"),
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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 ::style_traits::SpecifiedValueInfo for #name #ty_generics
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#where_clause
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{
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const SUPPORTED_TYPES: u8 = #types_value;
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}
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}
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}
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fn derive_struct_fields(fields: &Fields, supports_body: &mut Tokens) {
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let fields = match *fields {
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Fields::Unit => return,
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Fields::Named(ref fields) => fields.named.iter(),
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Fields::Unnamed(ref fields) => fields.unnamed.iter(),
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};
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supports_body.append_all(fields.map(|field| {
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let attrs = cg::parse_field_attrs::<CssFieldAttrs>(field);
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if attrs.skip {
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return quote!();
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}
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let ty = &field.ty;
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quote! {
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| <#ty as ::style_traits::SpecifiedValueInfo>::SUPPORTED_TYPES
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}
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}));
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}
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