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Opt into field bounds when deriving ToCss, instead of opting out

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This commit is contained in:
Anthony Ramine 2018-03-08 11:07:57 +01:00
parent 8133f788cf
commit 859002a81f
8 changed files with 89 additions and 67 deletions
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57
components/style_derive/to_css.rs
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@ -2,28 +2,41 @@
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use cg::{self, WhereClause};
use cg;
use darling::util::Override;
use quote::{ToTokens, Tokens};
use syn::{self, Data, Path};
use syn::{self, Data, GenericParam, Path, WhereClause};
use synstructure::{BindingInfo, Structure, VariantInfo};
pub fn derive(input: syn::DeriveInput) -> Tokens {
let name = &input.ident;
let trait_path = parse_quote!(::style_traits::ToCss);
let (impl_generics, ty_generics, mut where_clause) =
cg::trait_parts(&input, &trait_path);
pub fn derive(mut input: syn::DeriveInput) -> Tokens {
let mut where_clause = input.generics.where_clause.take();
for param in &input.generics.params {
let param = match *param {
GenericParam::Type(ref param) => param,
_ => continue,
};
cg::add_predicate(
&mut where_clause,
parse_quote!(#param: ::style_traits::ToCss),
);
}
let input_attrs = cg::parse_input_attrs::<CssInputAttrs>(&input);
if let Data::Enum(_) = input.data {
assert!(input_attrs.function.is_none(), "#[css(function)] is not allowed on enums");
assert!(!input_attrs.comma, "#[css(comma)] is not allowed on enums");
}
let s = Structure::new(&input);
let match_body = s.each_variant(|variant| {
derive_variant_arm(variant, &mut where_clause)
});
let match_body = {
let s = Structure::new(&input);
s.each_variant(|variant| {
derive_variant_arm(variant, &mut where_clause)
})
};
input.generics.where_clause = where_clause;
let name = &input.ident;
let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
let mut impls = quote! {
impl #impl_generics ::style_traits::ToCss for #name #ty_generics #where_clause {
@ -34,7 +47,7 @@ pub fn derive(input: syn::DeriveInput) -> Tokens {
dest: &mut ::style_traits::CssWriter<W>,
) -> ::std::fmt::Result
where
W: ::std::fmt::Write
W: ::std::fmt::Write,
{
match *self {
#match_body
@ -61,7 +74,7 @@ pub fn derive(input: syn::DeriveInput) -> Tokens {
fn derive_variant_arm(
variant: &VariantInfo,
where_clause: &mut WhereClause,
generics: &mut Option<WhereClause>,
) -> Tokens {
let bindings = variant.bindings();
let identifier = cg::to_css_identifier(variant.ast().ident.as_ref());
@ -83,7 +96,7 @@ fn derive_variant_arm(
::std::fmt::Write::write_str(dest, #keyword)
}
} else if !bindings.is_empty() {
derive_variant_fields_expr(bindings, where_clause, separator)
derive_variant_fields_expr(bindings, generics, separator)
} else {
quote! {
::std::fmt::Write::write_str(dest, #identifier)
@ -109,7 +122,7 @@ fn derive_variant_arm(
fn derive_variant_fields_expr(
bindings: &[BindingInfo],
where_clause: &mut WhereClause,
where_clause: &mut Option<WhereClause>,
separator: &str,
) -> Tokens {
let mut iter = bindings.iter().filter_map(|binding| {
@ -125,8 +138,9 @@ fn derive_variant_fields_expr(
None => return quote! { Ok(()) },
};
if !attrs.iterable && iter.peek().is_none() {
if !attrs.ignore_bound {
where_clause.add_trait_bound(&first.ast().ty);
if attrs.field_bound {
let ty = &first.ast().ty;
cg::add_predicate(where_clause, parse_quote!(#ty: ::style_traits::ToCss));
}
let mut expr = quote! { ::style_traits::ToCss::to_css(#first, dest) };
if let Some(condition) = attrs.skip_if {
@ -154,7 +168,7 @@ fn derive_variant_fields_expr(
fn derive_single_field_expr(
field: &BindingInfo,
attrs: CssFieldAttrs,
where_clause: &mut WhereClause,
where_clause: &mut Option<WhereClause>,
) -> Tokens {
let mut expr = if attrs.iterable {
if let Some(if_empty) = attrs.if_empty {
@ -177,8 +191,9 @@ fn derive_single_field_expr(
}
}
} else {
if !attrs.ignore_bound {
where_clause.add_trait_bound(&field.ast().ty);
if attrs.field_bound {
let ty = &field.ast().ty;
cg::add_predicate(where_clause, parse_quote!(#ty: ::style_traits::ToCss));
}
quote! { writer.item(#field)?; }
};
@ -218,7 +233,7 @@ pub struct CssVariantAttrs {
#[derive(Default, FromField)]
struct CssFieldAttrs {
if_empty: Option<String>,
ignore_bound: bool,
field_bound: bool,
iterable: bool,
skip: bool,
skip_if: Option<Path>,