Introduce #[css(skip)]

components/style/font_face.rs

@@ -48,24 +48,16 @@ impl OneOrMoreSeparated for Source {
 /// `url()` function.
 ///
 /// <https://drafts.csswg.org/css-fonts/#src-desc>
-#[derive(Clone, Debug, Eq, PartialEq)]
 #[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
+#[derive(Clone, Debug, Eq, PartialEq, ToCss)]
 pub struct UrlSource {
     /// The specified url.
     pub url: SpecifiedUrl,
     /// The format hints specified with the `format()` function.
+    #[css(skip)]
     pub format_hints: Vec<String>,
 }
 
-impl ToCss for UrlSource {
-    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
-    where
-        W: Write,
-    {
-        self.url.to_css(dest)
-    }
-}
-
 /// A font-display value for a @font-face rule.
 /// The font-display descriptor determines how a font face is displayed based
 /// on whether and when it is downloaded and ready to use.

components/style/gecko/url.rs

@@ -12,12 +12,12 @@ use gecko_bindings::sugar::refptr::RefPtr;
 use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
 use parser::ParserContext;
 use servo_arc::{Arc, RawOffsetArc};
-use std::fmt::{self, Write};
 use std::mem;
-use style_traits::{CssWriter, ToCss, ParseError};
+use style_traits::ParseError;
 
 /// A specified url() value for gecko. Gecko does not eagerly resolve SpecifiedUrls.
-#[derive(Clone, Debug, PartialEq)]
+#[css(function = "url")]
+#[derive(Clone, Debug, PartialEq, ToCss)]
 pub struct SpecifiedUrl {
     /// The URL in unresolved string form.
     ///
@@ -26,10 +26,12 @@ pub struct SpecifiedUrl {
     serialization: Arc<String>,
 
     /// The URL extra data.
+    #[css(skip)]
     pub extra_data: RefPtr<URLExtraData>,
 
     /// Cache ImageValue, if any, so that we can reuse it while rematching a
     /// a property with this specified url value.
+    #[css(skip)]
     pub image_value: Option<RefPtr<ImageValue>>,
 }
 trivial_to_computed_value!(SpecifiedUrl);
@@ -133,17 +135,6 @@ impl SpecifiedUrl {
     }
 }
 
-impl ToCss for SpecifiedUrl {
-    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
-    where
-        W: Write,
-    {
-        dest.write_str("url(")?;
-        self.serialization.to_css(dest)?;
-        dest.write_str(")")
-    }
-}
-
 impl MallocSizeOf for SpecifiedUrl {
     fn size_of(&self, _ops: &mut MallocSizeOfOps) -> usize {
         use gecko_bindings::bindings::Gecko_ImageValue_SizeOfIncludingThis;

components/style/properties/properties.mako.rs

@@ -1707,59 +1707,35 @@ impl PropertyId {
 
 /// A declaration using a CSS-wide keyword.
 #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-#[derive(Clone, PartialEq)]
+#[derive(Clone, PartialEq, ToCss)]
 pub struct WideKeywordDeclaration {
+    #[css(skip)]
     id: LonghandId,
     keyword: CSSWideKeyword,
 }
 
-impl ToCss for WideKeywordDeclaration {
-    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
-    where
-        W: fmt::Write,
-    {
-        self.keyword.to_css(dest)
-    }
-}
-
 /// An unparsed declaration that contains `var()` functions.
 #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-#[derive(Clone, PartialEq)]
+#[derive(Clone, PartialEq, ToCss)]
 pub struct VariableDeclaration {
+    #[css(skip)]
     id: LonghandId,
     #[cfg_attr(feature = "gecko", ignore_malloc_size_of = "XXX: how to handle this?")]
     value: Arc<UnparsedValue>,
 }
 
-impl ToCss for VariableDeclaration {
-    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
-    where
-        W: fmt::Write,
-    {
-        self.value.to_css(dest)
-    }
-}
-
 /// A custom property declaration with the property name and the declared value.
 #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-#[derive(Clone, PartialEq)]
+#[derive(Clone, PartialEq, ToCss)]
 pub struct CustomDeclaration {
     /// The name of the custom property.
+    #[css(skip)]
     pub name: ::custom_properties::Name,
     /// The value of the custom property.
     #[cfg_attr(feature = "gecko", ignore_malloc_size_of = "XXX: how to handle this?")]
     pub value: DeclaredValueOwned<Arc<::custom_properties::SpecifiedValue>>,
 }
 
-impl ToCss for CustomDeclaration {
-    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
-    where
-        W: fmt::Write,
-    {
-        self.value.to_css(dest)
-    }
-}
-
 impl fmt::Debug for PropertyDeclaration {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         self.id().to_css(&mut CssWriter::new(f))?;

components/style/values/computed/font.rs

@@ -40,13 +40,14 @@ pub use values::specified::font::{XTextZoom, XLang, MozScriptSizeMultiplier, Fon
 #[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
 pub struct FontWeight(pub u16);
 
-#[derive(Animate, ComputeSquaredDistance, MallocSizeOf, ToAnimatedZero)]
-#[derive(Clone, Copy, Debug, PartialEq)]
+#[derive(Animate, Clone, ComputeSquaredDistance, Copy, Debug, MallocSizeOf)]
+#[derive(PartialEq, ToAnimatedZero, ToCss)]
 /// The computed value of font-size
 pub struct FontSize {
     /// The size.
     pub size: NonNegativeLength,
     /// If derived from a keyword, the keyword and additional transformations applied to it
+    #[css(skip)]
     pub keyword_info: Option<KeywordInfo>,
 }
 
@@ -159,12 +160,6 @@ impl FontSize {
     }
 }
 
-impl ToCss for FontSize {
-    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result where W: fmt::Write {
-        self.size.to_css(dest)
-    }
-}
-
 /// XXXManishearth it might be better to
 /// animate this as computed, however this complicates
 /// clamping and might not be the right thing to do.

components/style/values/specified/font.rs

@@ -2015,9 +2015,9 @@ impl Parse for VariationValue<Number> {
 }
 
 
-#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToComputedValue)]
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToComputedValue, ToCss)]
 /// text-zoom. Enable if true, disable if false
-pub struct XTextZoom(pub bool);
+pub struct XTextZoom(#[css(skip)] pub bool);
 
 impl Parse for XTextZoom {
     fn parse<'i, 't>(_: &ParserContext, input: &mut Parser<'i, 't>) -> Result<XTextZoom, ParseError<'i>> {
@@ -2026,18 +2026,9 @@ impl Parse for XTextZoom {
     }
 }
 
-impl ToCss for XTextZoom {
-    fn to_css<W>(&self, _: &mut CssWriter<W>) -> fmt::Result
-    where
-        W: Write,
-    {
-        Ok(())
-    }
-}
-
-#[derive(Clone, Debug, MallocSizeOf, PartialEq, ToComputedValue)]
+#[derive(Clone, Debug, MallocSizeOf, PartialEq, ToComputedValue, ToCss)]
 /// Internal property that reflects the lang attribute
-pub struct XLang(pub Atom);
+pub struct XLang(#[css(skip)] pub Atom);
 
 impl XLang {
     #[inline]
@@ -2057,15 +2048,6 @@ impl Parse for XLang {
     }
 }
 
-impl ToCss for XLang {
-    fn to_css<W>(&self, _: &mut CssWriter<W>) -> fmt::Result
-    where
-        W: Write,
-    {
-        Ok(())
-    }
-}
-
 #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
 #[derive(Clone, Copy, Debug, PartialEq, ToCss)]
 /// Specifies the minimum font size allowed due to changes in scriptlevel.

components/style/values/specified/table.rs

@@ -6,12 +6,11 @@
 
 use cssparser::Parser;
 use parser::{Parse, ParserContext};
-use std::fmt;
-use style_traits::{CssWriter, ToCss, StyleParseErrorKind, ParseError};
+use style_traits::{StyleParseErrorKind, ParseError};
 
-#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToComputedValue)]
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToComputedValue, ToCss)]
 /// span. for `<col span>` pres attr
-pub struct XSpan(pub i32);
+pub struct XSpan(#[css(skip)] pub i32);
 
 impl Parse for XSpan {
     // never parse it, only set via presentation attribute
@@ -19,9 +18,3 @@ impl Parse for XSpan {
         Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError))
     }
 }
-
-impl ToCss for XSpan {
-    fn to_css<W>(&self, _: &mut CssWriter<W>) -> fmt::Result where W: fmt::Write {
-        Ok(())
-    }
-}

components/style_derive/to_css.rs

@@ -53,6 +53,9 @@ pub fn derive(input: syn::DeriveInput) -> Tokens {
             } else {
                 for binding in bindings {
                     let attrs = cg::parse_field_attrs::<CssFieldAttrs>(&binding.ast());
+                    if attrs.skip {
+                        continue;
+                    }
                     if !attrs.ignore_bound {
                         where_clause.add_trait_bound(&binding.ast().ty);
                     }
@@ -152,4 +155,5 @@ pub struct CssVariantAttrs {
 #[derive(Default, FromField)]
 struct CssFieldAttrs {
     ignore_bound: bool,
+    skip: bool,
 }

components/style_traits/values.rs

@@ -26,10 +26,12 @@ use std::fmt::{self, Write};
 ///   serialised like unit variants and its fields are surrounded by parentheses;
 /// * if `#[css(iterable)]` is found on a function variant, that variant needs
 ///   to have a single member, and that member needs to be iterable. The
-///   iterable will be serialized as the arguments for the function.
+///   iterable will be serialized as the arguments for the function;
 /// * if `#[css(dimension)]` is found on a variant, that variant needs
 ///   to have a single member. The variant would be serialized as a CSS
-///   dimension token, like: <member><identifier>.
+///   dimension token, like: <member><identifier>;
+/// * if `#[css(skip)]` is found on a field, the `ToCss` call for that field
+///   is skipped;
 /// * finally, one can put `#[css(derive_debug)]` on the whole type, to
 ///   implement `Debug` by a single call to `ToCss::to_css`.
 pub trait ToCss {