Make Rect<T> a struct tuple

It makes no sense to have named fields in some cases, notably to reuse
Rect<T> in BorderRadius<T>.

components/layout/display_list_builder.rs

@@ -1424,10 +1424,10 @@ impl FragmentDisplayListBuilding for Fragment {
                             details: BorderDetails::Image(ImageBorder {
                                 image: webrender_image,
                                 fill: border_style_struct.border_image_slice.fill,
-                                slice: SideOffsets2D::new(corners.top.resolve(webrender_image.height),
-                                                          corners.right.resolve(webrender_image.width),
-                                                          corners.bottom.resolve(webrender_image.height),
-                                                          corners.left.resolve(webrender_image.width)),
+                                slice: SideOffsets2D::new(corners.0.resolve(webrender_image.height),
+                                                          corners.1.resolve(webrender_image.width),
+                                                          corners.2.resolve(webrender_image.height),
+                                                          corners.3.resolve(webrender_image.width)),
                                 // TODO(gw): Support border-image-outset
                                 outset: SideOffsets2D::zero(),
                                 repeat_horizontal: convert_repeat_mode(border_style_struct.border_image_repeat.0),

components/style/properties/gecko.mako.rs

@@ -964,7 +964,7 @@ fn static_assert() {
 
     pub fn set_border_image_outset(&mut self, v: longhands::border_image_outset::computed_value::T) {
         % for side in SIDES:
-        v.${side.ident}.to_gecko_style_coord(&mut self.gecko.mBorderImageOutset.data_at_mut(${side.index}));
+        v.${side.index}.to_gecko_style_coord(&mut self.gecko.mBorderImageOutset.data_at_mut(${side.index}));
         % endfor
     }
 
@@ -1001,7 +1001,7 @@ fn static_assert() {
         use values::generics::border::BorderImageWidthSide;
 
         % for side in SIDES:
-        match v.${side.ident} {
+        match v.${side.index} {
             BorderImageWidthSide::Auto => {
                 self.gecko.mBorderImageWidth.data_at_mut(${side.index}).set_value(CoordDataValue::Auto)
             },
@@ -1026,7 +1026,7 @@ fn static_assert() {
         use gecko_bindings::structs::{NS_STYLE_BORDER_IMAGE_SLICE_NOFILL, NS_STYLE_BORDER_IMAGE_SLICE_FILL};
 
         % for side in SIDES:
-        v.offsets.${side.ident}.to_gecko_style_coord(&mut self.gecko.mBorderImageSlice.data_at_mut(${side.index}));
+        v.offsets.${side.index}.to_gecko_style_coord(&mut self.gecko.mBorderImageSlice.data_at_mut(${side.index}));
         % endfor
 
         let fill = if v.fill {

components/style/properties/helpers.mako.rs

@@ -901,8 +901,8 @@
             % endif
             })?;
             Ok(expanded! {
-                % for side in ["top", "right", "bottom", "left"]:
-                    ${to_rust_ident(sub_property_pattern % side)}: rect.${side},
+                % for index, side in enumerate(["top", "right", "bottom", "left"]):
+                    ${to_rust_ident(sub_property_pattern % side)}: rect.${index},
                 % endfor
             })
         }

components/style/properties/shorthand/border.mako.rs

@@ -25,20 +25,19 @@ ${helpers.four_sides_shorthand("border-style", "border-%s-style",
             BorderWidth::parse_quirky(context, i, AllowQuirks::Yes)
         })?;
         Ok(expanded! {
-            % for side in PHYSICAL_SIDES:
-                ${to_rust_ident('border-%s-width' % side)}: rect.${side},
-            % endfor
+            border_top_width: rect.0,
+            border_right_width: rect.1,
+            border_bottom_width: rect.2,
+            border_left_width: rect.3,
         })
     }
 
     impl<'a> ToCss for LonghandsToSerialize<'a>  {
         fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-            let rect = Rect {
-                % for side in PHYSICAL_SIDES:
-                ${side}: &self.border_${side}_width,
-                % endfor
-            };
-            rect.to_css(dest)
+            % for side in PHYSICAL_SIDES:
+            let ${side} = &self.border_${side}_width;
+            % endfor
+            Rect::new(top, right, bottom, left).to_css(dest)
         }
     }
 </%helpers:shorthand>

components/style/values/generics/rect.rs

@@ -9,29 +9,16 @@ use parser::{Parse, ParserContext};
 use std::fmt;
 use style_traits::ToCss;
 
-/// A CSS value made of four sides: top, right, bottom, and left.
+/// A CSS value made of four components, where its `ToCss` impl will try to
+/// serialize as few components as possible, like for example in `border-width`.
 #[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq, ToComputedValue)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-pub struct Rect<T> {
-    /// Top
-    pub top: T,
-    /// Right.
-    pub right: T,
-    /// Bottom.
-    pub bottom: T,
-    /// Left.
-    pub left: T,
-}
+pub struct Rect<T>(pub T, pub T, pub T, pub T);
 
 impl<T> Rect<T> {
     /// Returns a new `Rect<T>` value.
-    pub fn new(top: T, right: T, bottom: T, left: T) -> Self {
-        Rect {
-            top: top,
-            right: right,
-            bottom: bottom,
-            left: left,
-        }
+    pub fn new(first: T, second: T, third: T, fourth: T) -> Self {
+        Rect(first, second, third, fourth)
     }
 }
 
@@ -46,21 +33,21 @@ impl<T> Rect<T>
         -> Result<Self, ()>
         where Parse: Fn(&ParserContext, &mut Parser) -> Result<T, ()>
     {
-        let top = parse(context, input)?;
-        let right = if let Ok(right) = input.try(|i| parse(context, i)) { right } else {
-            // <top>
-            return Ok(Self::new(top.clone(), top.clone(), top.clone(), top));
+        let first = parse(context, input)?;
+        let second = if let Ok(second) = input.try(|i| parse(context, i)) { second } else {
+            // <first>
+            return Ok(Self::new(first.clone(), first.clone(), first.clone(), first));
         };
-        let bottom = if let Ok(bottom) = input.try(|i| parse(context, i)) { bottom } else {
-            // <top> <right>
-            return Ok(Self::new(top.clone(), right.clone(), top, right));
+        let third = if let Ok(third) = input.try(|i| parse(context, i)) { third } else {
+            // <first> <second>
+            return Ok(Self::new(first.clone(), second.clone(), first, second));
         };
-        let left = if let Ok(left) = input.try(|i| parse(context, i)) { left } else {
-            // <top> <right> <bottom>
-            return Ok(Self::new(top, right.clone(), bottom, right));
+        let fourth = if let Ok(fourth) = input.try(|i| parse(context, i)) { fourth } else {
+            // <first> <second> <third>
+            return Ok(Self::new(first, second.clone(), third, second));
         };
-        // <top> <right> <bottom> <left>
-        Ok(Self::new(top, right, bottom, left))
+        // <first> <second> <third> <fourth>
+        Ok(Self::new(first, second, third, fourth))
     }
 }
 
@@ -88,23 +75,23 @@ impl<T> ToCss for Rect<T>
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result
         where W: fmt::Write,
     {
-        self.top.to_css(dest)?;
-        let same_vertical = self.top == self.bottom;
-        let same_horizontal = self.right == self.left;
-        if same_vertical && same_horizontal && self.top == self.right {
+        self.0.to_css(dest)?;
+        let same_vertical = self.0 == self.2;
+        let same_horizontal = self.1 == self.3;
+        if same_vertical && same_horizontal && self.0 == self.1 {
             return Ok(());
         }
         dest.write_str(" ")?;
-        self.right.to_css(dest)?;
+        self.1.to_css(dest)?;
         if same_vertical && same_horizontal {
             return Ok(());
         }
         dest.write_str(" ")?;
-        self.bottom.to_css(dest)?;
+        self.2.to_css(dest)?;
         if same_horizontal {
             return Ok(());
         }
         dest.write_str(" ")?;
-        self.left.to_css(dest)
+        self.3.to_css(dest)
     }
 }