style: Move represents_keyword to the css attributes.

Bug: 1457635
Reviewed-by: xidorn
MozReview-Commit-ID: 21yuU4h34AQ

8 files changed, 24 insertions, 69 deletions

diff --git a/components/style/values/generics/border.rs b/components/style/values/generics/border.rs
index 6230a1cf36a..c25560ed0f1 100644
--- a/components/style/values/generics/border.rs
+++ b/components/style/values/generics/border.rs
@@ -23,12 +23,13 @@ pub enum BorderImageSideWidth<LengthOrPercentage, Number> {
 
 /// A generic value for the `border-image-slice` property.
 #[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo,
-         ToComputedValue)]
+         ToComputedValue, ToCss)]
 pub struct BorderImageSlice<NumberOrPercentage> {
     /// The offsets.
+    #[css(field_bound)]
     pub offsets: Rect<NumberOrPercentage>,
     /// Whether to fill the middle part.
-    #[value_info(represents_keyword)]
+    #[css(represents_keyword)]
     pub fill: bool,
 }
 
@@ -86,22 +87,6 @@ where
     }
 }
 
-impl<N> ToCss for BorderImageSlice<N>
-where
-    N: PartialEq + ToCss,
-{
-    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
-    where
-        W: Write,
-    {
-        self.offsets.to_css(dest)?;
-        if self.fill {
-            dest.write_str(" fill")?;
-        }
-        Ok(())
-    }
-}
-
 impl<L> BorderRadius<L> {
     /// Returns a new `BorderRadius<L>`.
     #[inline]
diff --git a/components/style/values/generics/effects.rs b/components/style/values/generics/effects.rs
index 7a76cdeb7bc..e5ee10fcada 100644
--- a/components/style/values/generics/effects.rs
+++ b/components/style/values/generics/effects.rs
@@ -4,14 +4,12 @@
 
 //! Generic types for CSS values related to effects.
 
-use std::fmt::{self, Write};
-use style_traits::values::{CssWriter, SequenceWriter, ToCss};
 #[cfg(feature = "gecko")]
 use values::specified::url::SpecifiedUrl;
 
 /// A generic value for a single `box-shadow`.
 #[derive(Animate, Clone, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo,
-         ToAnimatedValue, ToAnimatedZero)]
+         ToAnimatedValue, ToAnimatedZero, ToCss)]
 pub struct BoxShadow<Color, SizeLength, BlurShapeLength, ShapeLength> {
     /// The base shadow.
     pub base: SimpleShadow<Color, SizeLength, BlurShapeLength>,
@@ -19,7 +17,7 @@ pub struct BoxShadow<Color, SizeLength, BlurShapeLength, ShapeLength> {
     pub spread: ShapeLength,
     /// Whether this is an inset box shadow.
     #[animation(constant)]
-    #[value_info(represents_keyword)]
+    #[css(represents_keyword)]
     pub inset: bool,
 }
 
@@ -80,27 +78,3 @@ pub struct SimpleShadow<Color, SizeLength, ShapeLength> {
     /// Blur radius.
     pub blur: ShapeLength,
 }
-
-impl<Color, SizeLength, BlurShapeLength, ShapeLength> ToCss
-    for BoxShadow<Color, SizeLength, BlurShapeLength, ShapeLength>
-where
-    Color: ToCss,
-    SizeLength: ToCss,
-    BlurShapeLength: ToCss,
-    ShapeLength: ToCss,
-{
-    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
-    where
-        W: Write,
-    {
-        {
-            let mut writer = SequenceWriter::new(&mut *dest, " ");
-            writer.item(&self.base)?;
-            writer.item(&self.spread)?;
-        }
-        if self.inset {
-            dest.write_str(" inset")?;
-        }
-        Ok(())
-    }
-}
diff --git a/components/style/values/specified/font.rs b/components/style/values/specified/font.rs
index 8ec4354ab7a..266d7c52c09 100644
--- a/components/style/values/specified/font.rs
+++ b/components/style/values/specified/font.rs
@@ -1947,11 +1947,11 @@ pub struct FontSynthesis {
     /// If a `font-weight` is requested that the font family does not contain,
     /// the user agent may synthesize the requested weight from the weights
     /// that do exist in the font family.
-    #[value_info(represents_keyword)]
+    #[css(represents_keyword)]
     pub weight: bool,
     /// If a font-style is requested that the font family does not contain,
     /// the user agent may synthesize the requested style from the normal face in the font family.
-    #[value_info(represents_keyword)]
+    #[css(represents_keyword)]
     pub style: bool,
 }
 
diff --git a/components/style/values/specified/position.rs b/components/style/values/specified/position.rs
index 0f2669f0a02..17a5db17bcb 100644
--- a/components/style/values/specified/position.rs
+++ b/components/style/values/specified/position.rs
@@ -424,14 +424,14 @@ pub enum AutoFlow {
 }
 
 #[derive(Clone, Copy, Debug, Eq, MallocSizeOf, PartialEq, SpecifiedValueInfo,
-         ToComputedValue)]
+         ToComputedValue, ToCss)]
 /// Controls how the auto-placement algorithm works
 /// specifying exactly how auto-placed items get flowed into the grid
 pub struct GridAutoFlow {
     /// Specifiy how auto-placement algorithm fills each `row` or `column` in turn
     pub autoflow: AutoFlow,
     /// Specify use `dense` packing algorithm or not
-    #[value_info(represents_keyword)]
+    #[css(represents_keyword)]
     pub dense: bool,
 }
 
@@ -446,20 +446,6 @@ impl GridAutoFlow {
     }
 }
 
-impl ToCss for GridAutoFlow {
-    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
-    where
-        W: Write,
-    {
-        self.autoflow.to_css(dest)?;
-
-        if self.dense {
-            dest.write_str(" dense")?;
-        }
-        Ok(())
-    }
-}
-
 impl Parse for GridAutoFlow {
     /// [ row | column ] || dense
     fn parse<'i, 't>(
diff --git a/components/style_derive/specified_value_info.rs b/components/style_derive/specified_value_info.rs
index 11ad7a0d1b4..7aae081641d 100644
--- a/components/style_derive/specified_value_info.rs
+++ b/components/style_derive/specified_value_info.rs
@@ -140,13 +140,13 @@ fn derive_struct_fields<'a>(
                 values.push(value.to_string());
             }
         }
-        if info_attrs.represents_keyword {
+        let css_attrs = cg::parse_field_attrs::<CssFieldAttrs>(field);
+        if css_attrs.represents_keyword {
             let ident = field.ident.as_ref()
                 .expect("only named field should use represents_keyword");
             values.push(cg::to_css_identifier(ident.as_ref()));
             return None;
         }
-        let css_attrs = cg::parse_field_attrs::<CssFieldAttrs>(field);
         if let Some(if_empty) = css_attrs.if_empty {
             values.push(if_empty);
         }
@@ -176,6 +176,5 @@ struct ValueInfoVariantAttrs {
 #[darling(attributes(value_info), default)]
 #[derive(Default, FromField)]
 struct ValueInfoFieldAttrs {
-    represents_keyword: bool,
     other_values: Option<String>,
 }
diff --git a/components/style_derive/to_css.rs b/components/style_derive/to_css.rs
index 722107da0cd..7ac7d3a1ae7 100644
--- a/components/style_derive/to_css.rs
+++ b/components/style_derive/to_css.rs
@@ -189,6 +189,15 @@ fn derive_single_field_expr(
                 writer.item(&item)?;
             }
         }
+    } else if attrs.represents_keyword {
+        let ident =
+            field.ast().ident.as_ref().expect("Unnamed field with represents_keyword?");
+        let ident = cg::to_css_identifier(ident.as_ref());
+        quote! {
+            if *#field {
+                writer.raw_item(#ident)?;
+            }
+        }
     } else {
         if attrs.field_bound {
             let ty = &field.ast().ty;
@@ -236,5 +245,6 @@ pub struct CssFieldAttrs {
     pub field_bound: bool,
     pub iterable: bool,
     pub skip: bool,
+    pub represents_keyword: bool,
     pub skip_if: Option<Path>,
 }
diff --git a/components/style_traits/specified_value_info.rs b/components/style_traits/specified_value_info.rs
index 28e1eef25e6..d9f4578b1a8 100644
--- a/components/style_traits/specified_value_info.rs
+++ b/components/style_traits/specified_value_info.rs
@@ -56,8 +56,6 @@ pub type KeywordsCollectFn<'a> = &'a mut FnMut(&[&'static str]);
 /// * `#[value_info(starts_with_keyword)]` can be used on variants to
 ///   add the name of a non-unit variant (serialized like `ToCss`) into
 ///   `collect_completion_keywords`.
-/// * `#[value_info(represents_keyword)]` can be used on fields into
-///   `collect_completion_keywords`.
 pub trait SpecifiedValueInfo {
     /// Supported CssTypes by the given value type.
     ///
diff --git a/components/style_traits/values.rs b/components/style_traits/values.rs
index 481eb1aff6d..9a618067fd7 100644
--- a/components/style_traits/values.rs
+++ b/components/style_traits/values.rs
@@ -37,6 +37,9 @@ use std::fmt::{self, Write};
 /// * if `#[css(skip_if = "function")]` is found on a field, the `ToCss` call
 ///   for that field is skipped if `function` returns true. This function is
 ///   provided the field as an argument;
+/// * `#[css(represents_keyword)]` can be used on bool fields in order to
+///   serialize the field name if the field is true, or nothing otherwise.  It
+///   also collects those keywords for `SpecifiedValueInfo`.
 /// * 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 {