Derive HasViewportPercentage 🍷

Cargo.lock

@@ -605,7 +605,7 @@ name = "deny_public_fields"
 version = "0.0.1"
 dependencies = [
  "syn 0.11.11 (registry+https://github.com/rust-lang/crates.io-index)",
- "synstructure 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "synstructure 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1146,7 +1146,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "quote 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 0.11.11 (registry+https://github.com/rust-lang/crates.io-index)",
- "synstructure 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "synstructure 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1346,7 +1346,7 @@ version = "0.0.1"
 dependencies = [
  "quote 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 0.11.11 (registry+https://github.com/rust-lang/crates.io-index)",
- "synstructure 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "synstructure 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -2859,6 +2859,7 @@ dependencies = [
  "servo_config 0.0.1",
  "servo_url 0.0.1",
  "smallvec 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "style_derive 0.0.1",
  "style_traits 0.0.1",
  "time 0.1.37 (registry+https://github.com/rust-lang/crates.io-index)",
  "toml 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2866,6 +2867,15 @@ dependencies = [
  "walkdir 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "style_derive"
+version = "0.0.1"
+dependencies = [
+ "quote 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.11.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "synstructure 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "style_tests"
 version = "0.0.1"
@@ -2945,7 +2955,7 @@ dependencies = [
 
 [[package]]
 name = "synstructure"
-version = "0.5.0"
+version = "0.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "quote 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3650,7 +3660,7 @@ dependencies = [
 "checksum swapper 0.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "3ca610b32bb8bfc5e7f705480c3a1edfeb70b6582495d343872c8bee0dcf758c"
 "checksum syn 0.11.11 (registry+https://github.com/rust-lang/crates.io-index)" = "d3b891b9015c88c576343b9b3e41c2c11a51c219ef067b264bd9c8aa9b441dad"
 "checksum synom 0.11.3 (registry+https://github.com/rust-lang/crates.io-index)" = "a393066ed9010ebaed60b9eafa373d4b1baac186dd7e008555b0f702b51945b6"
-"checksum synstructure 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5ccc9780bf1aa601943988c2876ab22413c01ad1739689aa6af18d0aa0b3f38b"
+"checksum synstructure 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)" = "cf318c34a2f8381a4f3d4db2c91b45bca2b1cd8cbe56caced900647be164800c"
 "checksum syntex 0.58.1 (registry+https://github.com/rust-lang/crates.io-index)" = "a8f5e3aaa79319573d19938ea38d068056b826db9883a5d47f86c1cecc688f0e"
 "checksum syntex_errors 0.58.1 (registry+https://github.com/rust-lang/crates.io-index)" = "867cc5c2d7140ae7eaad2ae9e8bf39cb18a67ca651b7834f88d46ca98faadb9c"
 "checksum syntex_pos 0.58.1 (registry+https://github.com/rust-lang/crates.io-index)" = "13ad4762fe52abc9f4008e85c4fb1b1fe3aa91ccb99ff4826a439c7c598e1047"

components/style/Cargo.toml

@@ -58,6 +58,7 @@ serde_derive = {version = "0.9", optional = true}
 servo_atoms = {path = "../atoms", optional = true}
 servo_config = {path = "../config", optional = true}
 smallvec = "0.3.3"
+style_derive = {path = "../style_derive"}
 style_traits = {path = "../style_traits"}
 servo_url = {path = "../url", optional = true}
 time = "0.1"

components/style/lib.rs

@@ -78,6 +78,8 @@ extern crate selectors;
 #[cfg(feature = "servo")] extern crate servo_url;
 extern crate smallvec;
 #[macro_use]
+extern crate style_derive;
+#[macro_use]
 extern crate style_traits;
 extern crate time;
 #[allow(unused_extern_crates)]

components/style/macros.rs

@@ -38,19 +38,6 @@ macro_rules! define_numbered_css_keyword_enum {
     }
 }
 
-/// A macro used to implement HasViewportPercentage trait
-/// for a given type that may never contain viewport units.
-macro_rules! no_viewport_percentage {
-    ($name: ident) => {
-        impl $crate::values::HasViewportPercentage for $name {
-            #[inline]
-            fn has_viewport_percentage(&self) -> bool {
-                false
-            }
-        }
-    };
-}
-
 /// A macro for implementing `ComputedValueAsSpecified`, `Parse`
 /// and `HasViewportPercentage` traits for the enums defined
 /// using `define_css_keyword_enum` macro.

components/style/properties/helpers.mako.rs

@@ -81,13 +81,6 @@
             use values::HasViewportPercentage;
             use style_traits::ToCss;
 
-            impl HasViewportPercentage for SpecifiedValue {
-                fn has_viewport_percentage(&self) -> bool {
-                    let &SpecifiedValue(ref vec) = self;
-                    vec.iter().any(|ref x| x.has_viewport_percentage())
-                }
-            }
-
             pub mod single_value {
                 use cssparser::Parser;
                 use parser::{Parse, ParserContext};
@@ -168,7 +161,7 @@
             }
 
             /// The specified value of ${name}.
-            #[derive(Debug, Clone, PartialEq)]
+            #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
             #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
             pub struct SpecifiedValue(pub Vec<single_value::SpecifiedValue>);
 

components/style/properties/longhand/background.mako.rs

@@ -236,13 +236,7 @@ ${helpers.single_keyword("background-origin",
         }
     }
 
-    impl HasViewportPercentage for ExplicitSize {
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
-        fn has_viewport_percentage(&self) -> bool {
-            return self.width.has_viewport_percentage() || self.height.has_viewport_percentage();
-        }
-    }
-
-    #[derive(Clone, PartialEq, Debug)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     #[allow(missing_docs)]
     pub struct ExplicitSize {
@@ -266,16 +260,7 @@ ${helpers.single_keyword("background-origin",
         }
     }
 
-    impl HasViewportPercentage for SpecifiedValue {
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
-        fn has_viewport_percentage(&self) -> bool {
-            match *self {
-                SpecifiedValue::Explicit(ref explicit_size) => explicit_size.has_viewport_percentage(),
-                _ => false
-            }
-        }
-    }
-
-    #[derive(Clone, PartialEq, Debug)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         Explicit(ExplicitSize),

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

@@ -208,17 +208,6 @@ ${helpers.predefined_type("border-image-source", "ImageLayer",
     use values::HasViewportPercentage;
     use values::specified::{LengthOrNumber, Number};
 
-    impl HasViewportPercentage for SpecifiedValue {
-        fn has_viewport_percentage(&self) -> bool {
-            let mut viewport_percentage = false;
-            for value in self.0.iter() {
-                let vp = value.has_viewport_percentage();
-                viewport_percentage = vp || viewport_percentage;
-            }
-            viewport_percentage
-        }
-    }
-
     pub mod computed_value {
         use values::computed::LengthOrNumber;
         #[derive(Debug, Clone, PartialEq)]
@@ -227,7 +216,7 @@ ${helpers.predefined_type("border-image-source", "ImageLayer",
                      pub LengthOrNumber, pub LengthOrNumber);
     }
 
-    #[derive(Debug, Clone, PartialEq)]
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue(pub Vec<LengthOrNumber>);
 
@@ -402,20 +391,6 @@ ${helpers.predefined_type("border-image-source", "ImageLayer",
     use values::HasViewportPercentage;
     use values::specified::{LengthOrPercentage, Number};
 
-    impl HasViewportPercentage for SpecifiedValue {
-        fn has_viewport_percentage(&self) -> bool {
-            let mut viewport_percentage = false;
-            for value in self.0.clone() {
-                let vp = match value {
-                    SingleSpecifiedValue::LengthOrPercentage(len) => len.has_viewport_percentage(),
-                    _ => false,
-                };
-                viewport_percentage = vp || viewport_percentage;
-            }
-            viewport_percentage
-        }
-    }
-
     pub mod computed_value {
         use values::computed::{LengthOrPercentage, Number};
         #[derive(Debug, Clone, PartialEq)]
@@ -432,7 +407,7 @@ ${helpers.predefined_type("border-image-source", "ImageLayer",
         }
     }
 
-    #[derive(Debug, Clone, PartialEq)]
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue(pub Vec<SingleSpecifiedValue>);
 
@@ -458,7 +433,7 @@ ${helpers.predefined_type("border-image-source", "ImageLayer",
         }
     }
 
-    #[derive(Debug, Clone, PartialEq)]
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SingleSpecifiedValue {
         LengthOrPercentage(LengthOrPercentage),

components/style/properties/longhand/box.mako.rs

@@ -274,18 +274,9 @@ ${helpers.single_keyword("position", "static absolute relative fixed",
 
     ${helpers.gecko_keyword_conversion(vertical_align.keyword)}
 
-    impl HasViewportPercentage for SpecifiedValue {
-        fn has_viewport_percentage(&self) -> bool {
-            match *self {
-                SpecifiedValue::LengthOrPercentage(ref length) => length.has_viewport_percentage(),
-                _ => false
-            }
-        }
-    }
-
     /// The `vertical-align` value.
     #[allow(non_camel_case_types)]
-    #[derive(Debug, Clone, PartialEq)]
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         % for keyword in vertical_align_keywords:
@@ -1048,15 +1039,6 @@ ${helpers.single_keyword("animation-fill-mode",
     use values::HasViewportPercentage;
     use values::specified::LengthOrPercentage;
 
-    impl HasViewportPercentage for SpecifiedValue {
-        fn has_viewport_percentage(&self) -> bool {
-            match *self {
-                SpecifiedValue::Repeat(ref length) => length.has_viewport_percentage(),
-                _ => false
-            }
-        }
-    }
-
     pub mod computed_value {
         use values::computed::LengthOrPercentage;
 
@@ -1065,7 +1047,7 @@ ${helpers.single_keyword("animation-fill-mode",
         pub struct T(pub Option<LengthOrPercentage>);
     }
 
-    #[derive(Debug, Clone, PartialEq)]
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         None,
@@ -1253,7 +1235,7 @@ ${helpers.predefined_type("scroll-snap-coordinate",
     /// Multiple transform functions compose a transformation.
     ///
     /// Some transformations can be expressed by other more general functions.
-    #[derive(Clone, Debug, PartialEq)]
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedOperation {
         /// Represents a 2D 2x3 matrix.
@@ -1328,41 +1310,6 @@ ${helpers.predefined_type("scroll-snap-coordinate",
         }
     }
 
-    impl HasViewportPercentage for SpecifiedOperation {
-        fn has_viewport_percentage(&self) -> bool {
-            match *self {
-                SpecifiedOperation::Translate(ref l1, None) |
-                SpecifiedOperation::TranslateX(ref l1) |
-                SpecifiedOperation::TranslateY(ref l1)  => {
-                    l1.has_viewport_percentage()
-                }
-                SpecifiedOperation::TranslateZ(ref l1) => {
-                    l1.has_viewport_percentage()
-                }
-                SpecifiedOperation::Translate(ref l1, Some(ref l2)) => {
-                    l1.has_viewport_percentage() ||
-                    l2.has_viewport_percentage()
-                }
-                SpecifiedOperation::Translate3D(ref l1, ref l2, ref l3) => {
-                    l1.has_viewport_percentage() ||
-                    l2.has_viewport_percentage() ||
-                    l3.has_viewport_percentage()
-                },
-                SpecifiedOperation::Perspective(ref length) => length.has_viewport_percentage(),
-                SpecifiedOperation::PrefixedMatrix{ ref e, ref f, .. } => {
-                    e.has_viewport_percentage() ||
-                    f.has_viewport_percentage()
-                },
-                SpecifiedOperation::PrefixedMatrix3D{ ref m41, ref m42, ref m43, .. } => {
-                    m41.has_viewport_percentage() ||
-                    m42.has_viewport_percentage() ||
-                    m43.has_viewport_percentage()
-                },
-                _ => false
-            }
-        }
-    }
-
     impl ToCss for SpecifiedOperation {
         fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
             use self::SpecifiedOperation::*;
@@ -1422,14 +1369,7 @@ ${helpers.predefined_type("scroll-snap-coordinate",
         }
     }
 
-    impl HasViewportPercentage for SpecifiedValue {
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
-        fn has_viewport_percentage(&self) -> bool {
-            let &SpecifiedValue(ref specified_ops) = self;
-            specified_ops.iter().any(|ref x| x.has_viewport_percentage())
-        }
-    }
-
-    #[derive(Clone, Debug, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue(Vec<SpecifiedOperation>);
 
@@ -2223,15 +2163,7 @@ ${helpers.single_keyword("transform-style",
         }
     }
 
-    impl HasViewportPercentage for SpecifiedValue {
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
-        fn has_viewport_percentage(&self) -> bool {
-            self.horizontal.has_viewport_percentage() ||
-            self.vertical.has_viewport_percentage() ||
-            self.depth.has_viewport_percentage()
-        }
-    }
-
-    #[derive(Clone, Debug, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue {
         horizontal: LengthOrPercentage,

components/style/properties/longhand/effects.mako.rs

@@ -98,13 +98,7 @@ ${helpers.predefined_type("clip",
     use values::specified::{Angle, CSSColor, Length, Shadow};
     use values::specified::url::SpecifiedUrl;
 
-    impl HasViewportPercentage for SpecifiedValue {
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
-        fn has_viewport_percentage(&self) -> bool {
-            self.0.iter().any(|ref x| x.has_viewport_percentage())
-        }
-    }
-
-    #[derive(Debug, Clone, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue(pub Vec<SpecifiedFilter>);
 

components/style/properties/longhand/font.mako.rs

@@ -2108,7 +2108,6 @@ ${helpers.single_keyword_system("font-variant-position",
     pub use self::computed_value::T as SpecifiedValue;
 
     impl ComputedValueAsSpecified for SpecifiedValue {}
-    no_viewport_percentage!(SpecifiedValue);
 
     pub mod computed_value {
         pub type T = f32;
@@ -2235,7 +2234,7 @@ ${helpers.single_keyword("-moz-math-variant",
     use values::computed::ComputedValueAsSpecified;
     use values::specified::length::{AU_PER_PT, FontBaseSize, NoCalcLength};
 
-    #[derive(Clone, PartialEq, Debug)]
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
     pub struct SpecifiedValue(pub NoCalcLength);
 
     pub mod computed_value {
@@ -2273,12 +2272,6 @@ ${helpers.single_keyword("-moz-math-variant",
         }
     }
 
-    impl HasViewportPercentage for SpecifiedValue {
-        fn has_viewport_percentage(&self) -> bool {
-            self.0.has_viewport_percentage()
-        }
-    }
-
     #[inline]
     pub fn get_initial_value() -> computed_value::T {
         Au((NS_MATHML_DEFAULT_SCRIPT_MIN_SIZE_PT as f32 * AU_PER_PT) as i32)

components/style/properties/longhand/inherited_table.mako.rs

@@ -65,14 +65,7 @@ ${helpers.single_keyword("caption-side", "top bottom",
         }
     }
 
-    impl HasViewportPercentage for SpecifiedValue {
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
-        fn has_viewport_percentage(&self) -> bool {
-            self.horizontal.has_viewport_percentage() ||
-            self.vertical.as_ref().map_or(false, |v| v.has_viewport_percentage())
-        }
-    }
-
-    #[derive(Clone, Debug, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue {
         pub horizontal: Length,

components/style/properties/longhand/inherited_text.mako.rs

@@ -12,16 +12,7 @@
     use style_traits::ToCss;
     use values::HasViewportPercentage;
 
-    impl HasViewportPercentage for SpecifiedValue {
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
-        fn has_viewport_percentage(&self) -> bool {
-            match *self {
-                SpecifiedValue::LengthOrPercentage(ref length) => length.has_viewport_percentage(),
-                _ => false
-            }
-        }
-    }
-
-    #[derive(Debug, Clone, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         Normal,
@@ -415,16 +406,7 @@ ${helpers.single_keyword("text-align-last",
     use values::HasViewportPercentage;
     use values::specified::AllowQuirks;
 
-    impl HasViewportPercentage for SpecifiedValue {
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
-        fn has_viewport_percentage(&self) -> bool {
-            match *self {
-                SpecifiedValue::Specified(ref length) => length.has_viewport_percentage(),
-                _ => false
-            }
-        }
-    }
-
-    #[derive(Debug, Clone, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         Normal,
@@ -501,16 +483,7 @@ ${helpers.single_keyword("text-align-last",
     use values::HasViewportPercentage;
     use values::specified::AllowQuirks;
 
-    impl HasViewportPercentage for SpecifiedValue {
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
-        fn has_viewport_percentage(&self) -> bool {
-            match *self {
-                SpecifiedValue::Specified(ref length) => length.has_viewport_percentage(),
-                _ => false
-            }
-        }
-    }
-
-    #[derive(Debug, Clone, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         Normal,
@@ -722,26 +695,11 @@ ${helpers.single_keyword("text-align-last",
     use values::specified::Shadow;
     use values::HasViewportPercentage;
 
-    impl HasViewportPercentage for SpecifiedValue {
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
-        fn has_viewport_percentage(&self) -> bool {
-            let &SpecifiedValue(ref vec) = self;
-            vec.iter().any(|ref x| x.has_viewport_percentage())
-        }
-    }
-
-    #[derive(Clone, PartialEq, Debug)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue(Vec<SpecifiedTextShadow>);
 
-    impl HasViewportPercentage for SpecifiedTextShadow {
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
-        fn has_viewport_percentage(&self) -> bool {
-            self.offset_x.has_viewport_percentage() ||
-            self.offset_y.has_viewport_percentage() ||
-            self.blur_radius.has_viewport_percentage()
-        }
-    }
-
-    #[derive(Clone, PartialEq, Debug)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedTextShadow {
         pub offset_x: specified::Length,

components/style/properties/longhand/outline.mako.rs

@@ -81,16 +81,10 @@ ${helpers.predefined_type("outline-color", "CSSColor", "computed::CSSColor::Curr
         specified::parse_border_width(context, input).map(SpecifiedValue)
     }
 
-    impl HasViewportPercentage for SpecifiedValue {
+    #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
-        fn has_viewport_percentage(&self) -> bool {
-            let &SpecifiedValue(ref length) = self;
-            length.has_viewport_percentage()
-        }
-    }
-
-    #[derive(Debug, Clone, PartialEq)]
     #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue(pub specified::Length);
+
     pub mod computed_value {
         use app_units::Au;
         pub type T = Au;

components/style/properties/longhand/position.mako.rs

@@ -181,17 +181,11 @@ ${helpers.predefined_type("flex-basis",
                 use values::HasViewportPercentage;
                 use values::specified::{AllowQuirks, ${MinMax}Length};
 
-                impl HasViewportPercentage for SpecifiedValue {
-                    fn has_viewport_percentage(&self) -> bool {
-                        self.0.has_viewport_percentage()
-                    }
-                }
-
                 pub mod computed_value {
                     pub type T = ::values::computed::${MinMax}Length;
                 }
 
-                #[derive(PartialEq, Clone, Debug)]
+                #[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
                 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
                 pub struct SpecifiedValue(${MinMax}Length);
 

components/style/values/computed/mod.rs

@@ -175,7 +175,7 @@ impl<T> ToComputedValue for T
 }
 
 /// A computed `<angle>` value.
-#[derive(Clone, PartialEq, PartialOrd, Copy, Debug)]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
 pub enum Angle {
     /// An angle with degree unit

components/style/values/generics/image.rs

@@ -32,7 +32,7 @@ pub enum Image<Gradient, ImageRect> {
 
 /// A CSS gradient.
 /// https://drafts.csswg.org/css-images/#gradients
-#[derive(Clone, PartialEq, Debug)]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct Gradient<LineDirection, Length, LengthOrPercentage, Position, Color> {
     /// Gradients can be linear or radial.
@@ -45,7 +45,7 @@ pub struct Gradient<LineDirection, Length, LengthOrPercentage, Position, Color>
     pub compat_mode: CompatMode,
 }
 
-#[derive(Clone, Copy, PartialEq, Debug)]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 /// Whether we used the modern notation or the compatibility `-webkit` prefix.
 pub enum CompatMode {
@@ -56,7 +56,7 @@ pub enum CompatMode {
 }
 
 /// A gradient kind.
-#[derive(Clone, Copy, Debug, PartialEq)]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum GradientKind<LineDirection, Length, LengthOrPercentage, Position> {
     /// A linear gradient.
@@ -66,7 +66,7 @@ pub enum GradientKind<LineDirection, Length, LengthOrPercentage, Position> {
 }
 
 /// A radial gradient's ending shape.
-#[derive(Clone, Copy, PartialEq, Debug)]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum EndingShape<Length, LengthOrPercentage> {
     /// A circular gradient.
@@ -76,7 +76,7 @@ pub enum EndingShape<Length, LengthOrPercentage> {
 }
 
 /// A circle shape.
-#[derive(Clone, Copy, PartialEq, Debug)]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum Circle<Length> {
     /// A circle radius.
@@ -86,7 +86,7 @@ pub enum Circle<Length> {
 }
 
 /// An ellipse shape.
-#[derive(Clone, Copy, PartialEq, Debug)]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum Ellipse<LengthOrPercentage> {
     /// An ellipse pair of radii.
@@ -104,10 +104,11 @@ define_css_keyword_enum!(ShapeExtent:
     "contain" => Contain,
     "cover" => Cover
 );
+no_viewport_percentage!(ShapeExtent);
 
 /// A gradient item.
 /// https://drafts.csswg.org/css-images-4/#color-stop-syntax
-#[derive(Clone, Copy, PartialEq, Debug)]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum GradientItem<Color, LengthOrPercentage> {
     /// A color stop.
@@ -118,7 +119,7 @@ pub enum GradientItem<Color, LengthOrPercentage> {
 
 /// A color stop.
 /// https://drafts.csswg.org/css-images/#typedef-color-stop-list
-#[derive(Clone, Copy, PartialEq)]
+#[derive(Clone, Copy, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct ColorStop<Color, LengthOrPercentage> {
     /// The color of this stop.
@@ -281,17 +282,6 @@ impl<D, L, LoP, P, C> ToCss for Gradient<D, L, LoP, P, C>
     }
 }
 
-impl<D, L, LoP, P, C> HasViewportPercentage for Gradient<D, L, LoP, P, C>
-    where L: HasViewportPercentage,
-          LoP: HasViewportPercentage,
-          P: HasViewportPercentage,
-{
-    fn has_viewport_percentage(&self) -> bool {
-        self.kind.has_viewport_percentage() ||
-        self.items.iter().any(|i| i.has_viewport_percentage())
-    }
-}
-
 impl<D, L, LoP, P, C> ToComputedValue for Gradient<D, L, LoP, P, C>
     where D: ToComputedValue,
           L: ToComputedValue,
@@ -333,21 +323,6 @@ impl<D, L, LoP, P> GradientKind<D, L, LoP, P> {
     }
 }
 
-impl<D, L, LoP, P> HasViewportPercentage for GradientKind<D, L, LoP, P>
-    where L: HasViewportPercentage,
-          LoP: HasViewportPercentage,
-          P: HasViewportPercentage
-{
-    fn has_viewport_percentage(&self) -> bool {
-        match *self {
-            GradientKind::Linear(_) => false,
-            GradientKind::Radial(ref shape, ref position) => {
-                shape.has_viewport_percentage() || position.has_viewport_percentage()
-            },
-        }
-    }
-}
-
 impl<D, L, LoP, P> ToComputedValue for GradientKind<D, L, LoP, P>
     where D: ToComputedValue,
           L: ToComputedValue,
@@ -423,22 +398,6 @@ impl<L, LoP> ToCss for EndingShape<L, LoP>
     }
 }
 
-impl<L, LoP> HasViewportPercentage for EndingShape<L, LoP>
-    where L: HasViewportPercentage, LoP: HasViewportPercentage,
-{
-    fn has_viewport_percentage(&self) -> bool {
-        match *self {
-            EndingShape::Circle(Circle::Radius(ref length)) => {
-                length.has_viewport_percentage()
-            },
-            EndingShape::Ellipse(Ellipse::Radii(ref x, ref y)) => {
-                x.has_viewport_percentage() || y.has_viewport_percentage()
-            },
-            _ => false,
-        }
-    }
-}
-
 impl<L, LoP> ToComputedValue for EndingShape<L, LoP>
     where L: ToComputedValue, LoP: ToComputedValue,
 {
@@ -497,17 +456,6 @@ impl<C, L> ToCss for GradientItem<C, L>
     }
 }
 
-impl<C, L> HasViewportPercentage for GradientItem<C, L>
-    where L: HasViewportPercentage,
-{
-    fn has_viewport_percentage(&self) -> bool {
-        match *self {
-            GradientItem::ColorStop(ref stop) => stop.has_viewport_percentage(),
-            GradientItem::InterpolationHint(ref hint) => hint.has_viewport_percentage(),
-        }
-    }
-}
-
 impl<C, L> ToComputedValue for GradientItem<C, L>
     where C: ToComputedValue, L: ToComputedValue,
 {
@@ -562,14 +510,6 @@ impl<C, L> ToCss for ColorStop<C, L>
     }
 }
 
-impl<C, L> HasViewportPercentage for ColorStop<C, L>
-    where L: HasViewportPercentage,
-{
-    fn has_viewport_percentage(&self) -> bool {
-        self.position.as_ref().map_or(false, HasViewportPercentage::has_viewport_percentage)
-    }
-}
-
 impl<C, L> ToComputedValue for ColorStop<C, L>
     where C: ToComputedValue, L: ToComputedValue,
 {

components/style/values/generics/position.rs

@@ -5,10 +5,9 @@
 //! Generic types for CSS handling of specified and computed values of
 //! [`position`](https://drafts.csswg.org/css-backgrounds-3/#position)
 
-use values::HasViewportPercentage;
 use values::computed::{Context, ToComputedValue};
 
-#[derive(Clone, Copy, Debug, PartialEq)]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 /// A generic type for representing a CSS [position](https://drafts.csswg.org/css-values/#position).
 pub struct Position<H, V> {
@@ -28,13 +27,6 @@ impl<H, V> Position<H, V> {
     }
 }
 
-impl<H: HasViewportPercentage, V: HasViewportPercentage> HasViewportPercentage for Position<H, V> {
-    #[inline]
-    fn has_viewport_percentage(&self) -> bool {
-        self.horizontal.has_viewport_percentage() || self.vertical.has_viewport_percentage()
-    }
-}
-
 impl<H: ToComputedValue, V: ToComputedValue> ToComputedValue for Position<H, V> {
     type ComputedValue = Position<<H as ToComputedValue>::ComputedValue,
                                   <V as ToComputedValue>::ComputedValue>;

components/style/values/mod.rs

@@ -16,6 +16,7 @@ use std::borrow::Cow;
 use std::fmt::{self, Debug};
 use std::hash;
 use style_traits::ToCss;
+pub use style_traits::HasViewportPercentage;
 
 pub mod computed;
 pub mod generics;
@@ -30,24 +31,11 @@ pub type CSSInteger = i32;
 /// The default font size.
 pub const FONT_MEDIUM_PX: i32 = 16;
 
-/// A trait used to query whether this value has viewport units.
-pub trait HasViewportPercentage {
-    /// Returns true if this value has viewport units.
-    fn has_viewport_percentage(&self) -> bool;
-}
-
-impl<T: HasViewportPercentage> HasViewportPercentage for Box<T> {
-    #[inline]
-    fn has_viewport_percentage(&self) -> bool {
-        (**self).has_viewport_percentage()
-    }
-}
-
 define_keyword_type!(None_, "none");
 define_keyword_type!(Auto, "auto");
 define_keyword_type!(Normal, "normal");
 
-#[derive(Clone, PartialEq, Copy)]
+#[derive(Clone, Copy, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 /// A struct representing one of two kinds of values.
 pub enum Either<A, B> {
@@ -75,15 +63,6 @@ impl<A: ToCss, B: ToCss> ToCss for Either<A, B> {
     }
 }
 
-impl<A: HasViewportPercentage, B: HasViewportPercentage> HasViewportPercentage for Either<A, B> {
-    fn has_viewport_percentage(&self) -> bool {
-        match *self {
-            Either::First(ref v) => v.has_viewport_percentage(),
-            Either::Second(ref v) => v.has_viewport_percentage(),
-        }
-    }
-}
-
 impl<A: Parse, B: Parse> Parse for Either<A, B> {
     fn parse(context: &ParserContext, input: &mut Parser) -> Result<Either<A, B>, ()> {
         if let Ok(v) = input.try(|i| A::parse(context, i)) {
@@ -209,3 +188,4 @@ define_css_keyword_enum!(ExtremumLength:
                          "-moz-min-content" => MinContent,
                          "-moz-fit-content" => FitContent,
                          "-moz-available" => FillAvailable);
+no_viewport_percentage!(ExtremumLength);

components/style/values/specified/grid.rs

@@ -221,7 +221,7 @@ impl<L: ToComputedValue> ToComputedValue for TrackBreadth<L> {
     }
 }
 
-#[derive(Clone, PartialEq, Debug)]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 /// A `<track-size>` type for explicit grid track sizing. Like `<track-breadth>`, this is
 /// generic only to avoid code bloat. It only takes `<length-percentage>`
@@ -321,17 +321,6 @@ impl<L: ToCss> ToCss for TrackSize<L> {
     }
 }
 
-impl HasViewportPercentage for TrackSize<LengthOrPercentage> {
-    #[inline]
-    fn has_viewport_percentage(&self) -> bool {
-        match *self {
-            TrackSize::Breadth(ref b) => b.has_viewport_percentage(),
-            TrackSize::MinMax(ref inf_b, ref b) => inf_b.has_viewport_percentage() || b.has_viewport_percentage(),
-            TrackSize::FitContent(ref lop) => lop.has_viewport_percentage(),
-        }
-    }
-}
-
 impl<L: ToComputedValue> ToComputedValue for TrackSize<L> {
     type ComputedValue = TrackSize<L::ComputedValue>;
 

components/style/values/specified/image.rs

@@ -54,7 +54,7 @@ pub type GradientKind = GenericGradientKind<
 >;
 
 /// A specified gradient line direction.
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum LineDirection {
     /// An angular direction.

components/style/values/specified/length.rs

@@ -531,7 +531,7 @@ impl NoCalcLength {
 /// This is commonly used for the `<length>` values.
 ///
 /// https://drafts.csswg.org/css-values/#lengths
-#[derive(Clone, PartialEq, Debug)]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum Length {
     /// The internal length type that cannot parse `calc`
@@ -549,15 +549,6 @@ impl From<NoCalcLength> for Length {
     }
 }
 
-impl HasViewportPercentage for Length {
-    fn has_viewport_percentage(&self) -> bool {
-        match *self {
-            Length::NoCalc(ref inner) => inner.has_viewport_percentage(),
-            Length::Calc(ref calc) => calc.has_viewport_percentage(),
-        }
-    }
-}
-
 impl ToCss for Length {
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
         match *self {
@@ -713,7 +704,7 @@ impl<T: Parse> Either<Length, T> {
 /// As of today, only `-moz-image-rect` supports percentages without length.
 /// This is not a regression, and that's a non-standard extension anyway, so I'm
 /// not implementing it for now.
-#[derive(Clone, PartialEq, Copy, Debug)]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct Percentage(pub CSSFloat);
 
@@ -754,7 +745,7 @@ impl Parse for Percentage {
 impl ComputedValueAsSpecified for Percentage {}
 
 /// A length or a percentage value.
-#[derive(Clone, PartialEq, Debug)]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[allow(missing_docs)]
 pub enum LengthOrPercentage {
@@ -786,16 +777,6 @@ impl From<Percentage> for LengthOrPercentage {
     }
 }
 
-impl HasViewportPercentage for LengthOrPercentage {
-    fn has_viewport_percentage(&self) -> bool {
-        match *self {
-            LengthOrPercentage::Length(ref length) => length.has_viewport_percentage(),
-            LengthOrPercentage::Calc(ref calc) => calc.has_viewport_percentage(),
-            _ => false
-        }
-    }
-}
-
 impl ToCss for LengthOrPercentage {
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
         match *self {
@@ -914,7 +895,7 @@ impl LengthOrPercentage {
 }
 
 /// Either a `<length>`, a `<percentage>`, or the `auto` keyword.
-#[derive(Clone, PartialEq, Debug)]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[allow(missing_docs)]
 pub enum LengthOrPercentageOrAuto {
@@ -938,16 +919,6 @@ impl From<Percentage> for LengthOrPercentageOrAuto {
     }
 }
 
-impl HasViewportPercentage for LengthOrPercentageOrAuto {
-    fn has_viewport_percentage(&self) -> bool {
-        match *self {
-            LengthOrPercentageOrAuto::Length(ref length) => length.has_viewport_percentage(),
-            LengthOrPercentageOrAuto::Calc(ref calc) => calc.has_viewport_percentage(),
-            _ => false
-        }
-    }
-}
-
 impl ToCss for LengthOrPercentageOrAuto {
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
         match *self {
@@ -1036,7 +1007,7 @@ impl LengthOrPercentageOrAuto {
 }
 
 /// Either a `<length>`, a `<percentage>`, or the `none` keyword.
-#[derive(Clone, PartialEq, Debug)]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[allow(missing_docs)]
 pub enum LengthOrPercentageOrNone {
@@ -1046,16 +1017,6 @@ pub enum LengthOrPercentageOrNone {
     None,
 }
 
-impl HasViewportPercentage for LengthOrPercentageOrNone {
-    fn has_viewport_percentage(&self) -> bool {
-        match *self {
-            LengthOrPercentageOrNone::Length(ref length) => length.has_viewport_percentage(),
-            LengthOrPercentageOrNone::Calc(ref calc) => calc.has_viewport_percentage(),
-            _ => false
-        }
-    }
-}
-
 impl ToCss for LengthOrPercentageOrNone {
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
         match *self {
@@ -1133,7 +1094,7 @@ pub type LengthOrAuto = Either<Length, Auto>;
 
 /// Either a `<length>` or a `<percentage>` or the `auto` keyword or the
 /// `content` keyword.
-#[derive(Clone, PartialEq, Debug)]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum LengthOrPercentageOrAutoOrContent {
     /// A `<length>`.
@@ -1185,16 +1146,6 @@ impl LengthOrPercentageOrAutoOrContent {
     }
 }
 
-impl HasViewportPercentage for LengthOrPercentageOrAutoOrContent {
-    fn has_viewport_percentage(&self) -> bool {
-        match *self {
-            LengthOrPercentageOrAutoOrContent::Length(ref length) => length.has_viewport_percentage(),
-            LengthOrPercentageOrAutoOrContent::Calc(ref calc) => calc.has_viewport_percentage(),
-            _ => false
-        }
-    }
-}
-
 impl ToCss for LengthOrPercentageOrAutoOrContent {
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
         match *self {
@@ -1227,7 +1178,7 @@ impl LengthOrNumber {
 /// A value suitable for a `min-width` or `min-height` property.
 /// Unlike `max-width` or `max-height` properties, a MinLength can be
 /// `auto`, and cannot be `none`.
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[allow(missing_docs)]
 pub enum MinLength {
@@ -1236,15 +1187,6 @@ pub enum MinLength {
     ExtremumLength(ExtremumLength),
 }
 
-impl HasViewportPercentage for MinLength {
-    fn has_viewport_percentage(&self) -> bool {
-        match *self {
-            MinLength::LengthOrPercentage(ref lop) => lop.has_viewport_percentage(),
-            _ => false
-        }
-    }
-}
-
 impl ToCss for MinLength {
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
         match *self {
@@ -1277,7 +1219,7 @@ impl MinLength {
 }
 
 /// A value suitable for a `max-width` or `max-height` property.
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[allow(missing_docs)]
 pub enum MaxLength {
@@ -1286,14 +1228,6 @@ pub enum MaxLength {
     ExtremumLength(ExtremumLength),
 }
 
-impl HasViewportPercentage for MaxLength {
-    fn has_viewport_percentage(&self) -> bool {
-        match *self {
-            MaxLength::LengthOrPercentage(ref lop) => lop.has_viewport_percentage(),
-            _ => false
-        }
-    }
-}
 
 impl ToCss for MaxLength {
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {

components/style/values/specified/mod.rs

@@ -21,7 +21,7 @@ use std::fmt;
 use std::io::Write;
 use style_traits::ToCss;
 use style_traits::values::specified::AllowedNumericType;
-use super::{Auto, CSSFloat, CSSInteger, HasViewportPercentage, Either, None_};
+use super::{Auto, CSSFloat, CSSInteger, Either, None_};
 use super::computed::{self, Context};
 use super::computed::{Shadow as ComputedShadow, ToComputedValue};
 use super::generics::BorderRadiusSize as GenericBorderRadiusSize;
@@ -76,8 +76,6 @@ impl ComputedValueAsSpecified for SpecifiedUrl {}
 no_viewport_percentage!(SpecifiedUrl);
 }
 
-no_viewport_percentage!(i32);  // For PropertyDeclaration::Order
-
 #[derive(Clone, PartialEq, Debug)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[allow(missing_docs)]
@@ -289,7 +287,7 @@ impl Parse for BorderRadiusSize {
     }
 }
 
-#[derive(Clone, PartialEq, Copy, Debug)]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
 /// An angle consisting of a value and a unit.
 ///
@@ -455,7 +453,7 @@ pub fn parse_border_width(context: &ParserContext, input: &mut Parser) -> Result
     })
 }
 
-#[derive(Clone, PartialEq, Debug)]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[allow(missing_docs)]
 pub enum BorderWidth {
@@ -507,15 +505,6 @@ impl ToCss for BorderWidth {
     }
 }
 
-impl HasViewportPercentage for BorderWidth {
-    fn has_viewport_percentage(&self) -> bool {
-        match *self {
-            BorderWidth::Thin | BorderWidth::Medium | BorderWidth::Thick => false,
-            BorderWidth::Width(ref length) => length.has_viewport_percentage()
-        }
-    }
-}
-
 impl ToComputedValue for BorderWidth {
     type ComputedValue = Au;
 
@@ -950,7 +939,7 @@ pub type TrackList = GenericTrackList<TrackSizeOrRepeat>;
 /// `<track-list> | none`
 pub type TrackListOrNone = Either<TrackList, None_>;
 
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[allow(missing_docs)]
 pub struct Shadow {
@@ -962,15 +951,6 @@ pub struct Shadow {
     pub inset: bool,
 }
 
-impl HasViewportPercentage for Shadow {
-    fn has_viewport_percentage(&self) -> bool {
-        self.offset_x.has_viewport_percentage() ||
-        self.offset_y.has_viewport_percentage() ||
-        self.blur_radius.has_viewport_percentage() ||
-        self.spread_radius.has_viewport_percentage()
-    }
-}
-
 impl ToComputedValue for Shadow {
     type ComputedValue = ComputedShadow;
 
@@ -1230,16 +1210,7 @@ impl LengthOrPercentageOrNumber {
     }
 }
 
-impl HasViewportPercentage for ClipRect {
+#[derive(Clone, Debug, HasViewportPercentage, PartialEq)]
-    fn has_viewport_percentage(&self) -> bool {
-        self.top.as_ref().map_or(false, |x| x.has_viewport_percentage()) ||
-        self.right.as_ref().map_or(false, |x| x.has_viewport_percentage()) ||
-        self.bottom.as_ref().map_or(false, |x| x.has_viewport_percentage()) ||
-        self.left.as_ref().map_or(false, |x| x.has_viewport_percentage())
-    }
-}
-
-#[derive(Clone, Debug, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 /// rect(<top>, <left>, <bottom>, <right>) used by clip and image-region
 pub struct ClipRect {

components/style_derive/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "style_derive"
+version = "0.0.1"
+authors = ["The Servo Project Developers"]
+license = "MPL-2.0"
+publish = false
+
+[lib]
+path = "lib.rs"
+proc-macro = true
+
+[dependencies]
+quote = "0.3"
+syn = "0.11"
+synstructure = "0.5.2"

components/style_derive/has_viewport_percentage.rs

@@ -0,0 +1,56 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * 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 quote;
+use syn;
+use synstructure;
+
+pub fn derive(input: syn::DeriveInput) -> quote::Tokens {
+    let name = &input.ident;
+    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
+    let mut where_clause = where_clause.clone();
+    for param in &input.generics.ty_params {
+        where_clause.predicates.push(where_predicate(syn::Ty::Path(None, param.ident.clone().into())))
+    }
+
+    let style = synstructure::BindStyle::Ref.into();
+    let match_body = synstructure::each_variant(&input, &style, |bindings, _| {
+        let (first, rest) = match bindings.split_first() {
+            None => return Some(quote!(false)),
+            Some(pair) => pair,
+        };
+        let mut expr = quote!(::style_traits::HasViewportPercentage::has_viewport_percentage(#first));
+        for binding in rest {
+            where_clause.predicates.push(where_predicate(binding.field.ty.clone()));
+            expr = quote!(#expr || ::style_traits::HasViewportPercentage::has_viewport_percentage(#binding));
+        }
+        Some(expr)
+    });
+
+    quote! {
+        impl #impl_generics ::style_traits::HasViewportPercentage for #name #ty_generics #where_clause {
+            #[allow(unused_variables, unused_imports)]
+            #[inline]
+            fn has_viewport_percentage(&self) -> bool {
+                match *self {
+                    #match_body
+                }
+            }
+        }
+    }
+}
+
+fn where_predicate(ty: syn::Ty) -> syn::WherePredicate {
+    syn::WherePredicate::BoundPredicate(syn::WhereBoundPredicate {
+        bound_lifetimes: vec![],
+        bounded_ty: ty,
+        bounds: vec![syn::TyParamBound::Trait(
+            syn::PolyTraitRef {
+                bound_lifetimes: vec![],
+                trait_ref: syn::parse_path("::style_traits::HasViewportPercentage").unwrap(),
+            },
+            syn::TraitBoundModifier::None
+        )],
+    })
+}

components/style_derive/lib.rs

@@ -0,0 +1,18 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * 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/. */
+
+extern crate proc_macro;
+#[macro_use] extern crate quote;
+extern crate syn;
+extern crate synstructure;
+
+use proc_macro::TokenStream;
+
+mod has_viewport_percentage;
+
+#[proc_macro_derive(HasViewportPercentage)]
+pub fn derive_has_viewport_percentage(stream: TokenStream) -> TokenStream {
+    let input = syn::parse_derive_input(&stream.to_string()).unwrap();
+    has_viewport_percentage::derive(input).to_string().parse().unwrap()
+}

components/style_traits/lib.rs

@@ -63,6 +63,8 @@ pub enum CSSPixel {}
 pub mod cursor;
 #[macro_use]
 pub mod values;
+#[macro_use]
 pub mod viewport;
 
 pub use values::{ToCss, OneOrMoreCommaSeparated};
+pub use viewport::HasViewportPercentage;

components/style_traits/viewport.rs

@@ -20,6 +20,48 @@ define_css_keyword_enum!(Orientation:
                          "portrait" => Portrait,
                          "landscape" => Landscape);
 
+/// A trait used to query whether this value has viewport units.
+pub trait HasViewportPercentage {
+    /// Returns true if this value has viewport units.
+    fn has_viewport_percentage(&self) -> bool;
+}
+
+/// A macro used to implement HasViewportPercentage trait
+/// for a given type that may never contain viewport units.
+#[macro_export]
+macro_rules! no_viewport_percentage {
+    ($($name: ident),+) => {
+        $(impl $crate::HasViewportPercentage for $name {
+            #[inline]
+            fn has_viewport_percentage(&self) -> bool {
+                false
+            }
+        })+
+    };
+}
+
+no_viewport_percentage!(bool, f32);
+
+impl<T: HasViewportPercentage> HasViewportPercentage for Box<T> {
+    #[inline]
+    fn has_viewport_percentage(&self) -> bool {
+        (**self).has_viewport_percentage()
+    }
+}
+
+impl<T: HasViewportPercentage> HasViewportPercentage for Option<T> {
+    #[inline]
+    fn has_viewport_percentage(&self) -> bool {
+        self.as_ref().map_or(false, T::has_viewport_percentage)
+    }
+}
+
+impl<T: HasViewportPercentage> HasViewportPercentage for Vec<T> {
+    #[inline]
+    fn has_viewport_percentage(&self) -> bool {
+        self.iter().any(T::has_viewport_percentage)
+    }
+}
 
 /// A set of viewport descriptors:
 ///