1 files changed, 48 insertions, 0 deletions
diff --git a/servo/components/style/color/component.rs b/servo/components/style/color/component.rs
new file mode 100644
index 0000000000..9f101a460c
--- /dev/null
+++ b/servo/components/style/color/component.rs
@@ -0,0 +1,48 @@
+/* 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 https://mozilla.org/MPL/2.0/. */
+
+//! Parse/serialize and resolve a single color component.
+
+/// A single color component.
+#[derive(Clone, MallocSizeOf, PartialEq, ToShmem)]
+pub enum ColorComponent<ValueType> {
+    /// The "none" keyword.
+    None,
+    /// A absolute value.
+    Value(ValueType),
+}
+
+impl<ValueType> ColorComponent<ValueType> {
+    /// Return true if the component is "none".
+    #[inline]
+    pub fn is_none(&self) -> bool {
+        matches!(self, Self::None)
+    }
+
+    /// If the component contains a value, map it to another value.
+    pub fn map_value<OutType>(
+        self,
+        f: impl FnOnce(ValueType) -> OutType,
+    ) -> ColorComponent<OutType> {
+        match self {
+            Self::None => ColorComponent::None,
+            Self::Value(value) => ColorComponent::Value(f(value)),
+        }
+    }
+    /// Return the component as its value.
+    pub fn into_value(self) -> ValueType {
+        match self {
+            Self::None => panic!("value not available when component is None"),
+            Self::Value(value) => value,
+        }
+    }
+
+    /// Return the component as its value or a default value.
+    pub fn into_value_or(self, default: ValueType) -> ValueType {
+        match self {
+            Self::None => default,
+            Self::Value(value) => value,
+        }
+    }
+}