Bug 1288572: Introduce css(parse_condition). r?xidorn
This will allow us to add a pref for this, and to parse it only on chrome easily.
MozReview-Commit-ID: L1rsyc2A2hu
--- a/servo/components/style_derive/parse.rs
+++ b/servo/components/style_derive/parse.rs
@@ -7,16 +7,17 @@ use quote::Tokens;
use syn::DeriveInput;
use synstructure;
use to_css::CssVariantAttrs;
pub fn derive(input: DeriveInput) -> Tokens {
let name = &input.ident;
let s = synstructure::Structure::new(&input);
+ let mut saw_condition = false;
let match_body = s.variants().iter().fold(quote!(), |match_body, variant| {
let bindings = variant.bindings();
assert!(
bindings.is_empty(),
"Parse is only supported for single-variant enums for now"
);
let variant_attrs = cg::parse_variant_attrs_from_ast::<CssVariantAttrs>(&variant.ast());
@@ -24,49 +25,80 @@ pub fn derive(input: DeriveInput) -> Tok
return match_body;
}
let identifier = cg::to_css_identifier(
&variant_attrs.keyword.unwrap_or(variant.ast().ident.as_ref().into()),
);
let ident = &variant.ast().ident;
+ saw_condition |= variant_attrs.parse_condition.is_some();
+ let condition = match variant_attrs.parse_condition {
+ Some(ref p) => quote! { if #p(context) },
+ None => quote! { },
+ };
+
let mut body = quote! {
#match_body
- #identifier => Ok(#name::#ident),
+ #identifier #condition => Ok(#name::#ident),
};
-
let aliases = match variant_attrs.aliases {
Some(aliases) => aliases,
None => return body,
};
for alias in aliases.split(",") {
body = quote! {
#body
- #alias => Ok(#name::#ident),
+ #alias #condition => Ok(#name::#ident),
};
}
body
});
+ let context_ident = if saw_condition {
+ quote! { context }
+ } else {
+ quote! { _ }
+ };
+
+ let parse_body = if saw_condition {
+ quote! {
+ let location = input.current_source_location();
+ let ident = input.expect_ident()?;
+ match_ignore_ascii_case! { &ident,
+ #match_body
+ _ => Err(location.new_unexpected_token_error(
+ ::cssparser::Token::Ident(ident.clone())
+ ))
+ }
+ }
+ } else {
+ quote! { Self::parse(input) }
+ };
+
+
let parse_trait_impl = quote! {
impl ::parser::Parse for #name {
#[inline]
fn parse<'i, 't>(
- _: &::parser::ParserContext,
+ #context_ident: &::parser::ParserContext,
input: &mut ::cssparser::Parser<'i, 't>,
) -> Result<Self, ::style_traits::ParseError<'i>> {
- Self::parse(input)
+ #parse_body
}
}
};
+ if saw_condition {
+ return parse_trait_impl;
+ }
+
// TODO(emilio): It'd be nice to get rid of these, but that makes the
// conversion harder...
let methods_impl = quote! {
impl #name {
/// Parse this keyword.
#[inline]
pub fn parse<'i, 't>(
input: &mut ::cssparser::Parser<'i, 't>,
--- a/servo/components/style_derive/to_css.rs
+++ b/servo/components/style_derive/to_css.rs
@@ -230,16 +230,17 @@ pub struct CssInputAttrs {
#[darling(attributes(css), default)]
#[derive(Default, FromVariant)]
pub struct CssVariantAttrs {
pub function: Option<Override<String>>,
pub comma: bool,
pub dimension: bool,
pub keyword: Option<String>,
pub aliases: Option<String>,
+ pub parse_condition: Option<Path>,
pub skip: bool,
}
#[darling(attributes(css), default)]
#[derive(Default, FromField)]
pub struct CssFieldAttrs {
pub if_empty: Option<String>,
pub field_bound: bool,