Use generics for the vertical-align property

components/style/values/generics/box.rs

@@ -0,0 +1,49 @@
+/* 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/. */
+
+//! Generic types for box properties.
+
+use values::animated::ToAnimatedZero;
+
+/// A generic value for the `vertical-align` property.
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+#[derive(Animate, Clone, ComputeSquaredDistance, Copy, Debug, PartialEq)]
+#[derive(ToComputedValue, ToCss)]
+pub enum VerticalAlign<LengthOrPercentage> {
+    /// `baseline`
+    Baseline,
+    /// `sub`
+    Sub,
+    /// `super`
+    Super,
+    /// `top`
+    Top,
+    /// `text-top`
+    TextTop,
+    /// `middle`
+    Middle,
+    /// `bottom`
+    Bottom,
+    /// `text-bottom`
+    TextBottom,
+    /// `-moz-middle-with-baseline`
+    #[cfg(feature = "gecko")]
+    MozMiddleWithBaseline,
+    /// `<length-percentage>`
+    Length(LengthOrPercentage),
+}
+
+impl<L> VerticalAlign<L> {
+    /// Returns `baseline`.
+    #[inline]
+    pub fn baseline() -> Self {
+        VerticalAlign::Baseline
+    }
+}
+
+impl<L> ToAnimatedZero for VerticalAlign<L> {
+    fn to_animated_zero(&self) -> Result<Self, ()> {
+        Err(())
+    }
+}

components/style/values/generics/mod.rs

@@ -15,6 +15,8 @@ use super::CustomIdent;
 pub mod background;
 pub mod basic_shape;
 pub mod border;
+#[path = "box.rs"]
+pub mod box_;
 pub mod effects;
 pub mod flex;
 #[cfg(feature = "gecko")]