1 files changed, 134 insertions, 0 deletions
diff --git a/servo/components/style/properties_and_values/syntax/data_type.rs b/servo/components/style/properties_and_values/syntax/data_type.rs
new file mode 100644
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+++ b/servo/components/style/properties_and_values/syntax/data_type.rs
@@ -0,0 +1,134 @@
+/* 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/. */
+
+//! Used for parsing and serializing component names from the syntax string.
+
+use super::{Component, ComponentName, Multiplier};
+use std::fmt::{self, Debug, Write};
+use style_traits::{CssWriter, ToCss};
+
+/// <https://drafts.css-houdini.org/css-properties-values-api-1/#supported-names>
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq)]
+pub enum DataType {
+    /// Any valid `<length>` value
+    Length,
+    /// `<number>` values
+    Number,
+    /// Any valid <percentage> value
+    Percentage,
+    /// Any valid `<length>` or `<percentage>` value, any valid `<calc()>` expression combining
+    /// `<length>` and `<percentage>` components.
+    LengthPercentage,
+    /// Any valid `<color>` value
+    Color,
+    /// Any valid `<image>` value
+    Image,
+    /// Any valid `<url>` value
+    Url,
+    /// Any valid `<integer>` value
+    Integer,
+    /// Any valid `<angle>` value
+    Angle,
+    /// Any valid `<time>` value
+    Time,
+    /// Any valid `<resolution>` value
+    Resolution,
+    /// Any valid `<transform-function>` value
+    TransformFunction,
+    /// Any valid `<custom-ident>` value
+    CustomIdent,
+    /// A list of valid `<transform-function>` values. Note that "<transform-list>" is a pre-multiplied
+    /// data type name equivalent to "<transform-function>+"
+    TransformList,
+    /// Any valid `<string>` value
+    ///
+    /// <https://github.com/w3c/css-houdini-drafts/issues/1103>
+    String,
+}
+
+impl DataType {
+    /// Converts a component name from a pre-multiplied data type to its un-pre-multiplied equivalent.
+    ///
+    /// <https://drafts.css-houdini.org/css-properties-values-api-1/#pre-multiplied-data-type-name>
+    pub fn unpremultiply(&self) -> Option<Component> {
+        match *self {
+            DataType::TransformList => Some(Component {
+                name: ComponentName::DataType(DataType::TransformFunction),
+                multiplier: Some(Multiplier::Space),
+            }),
+            _ => None,
+        }
+    }
+
+    /// Parses a syntax component name.
+    pub fn from_str(ty: &str) -> Option<Self> {
+        Some(match ty.as_bytes() {
+            b"length" => DataType::Length,
+            b"number" => DataType::Number,
+            b"percentage" => DataType::Percentage,
+            b"length-percentage" => DataType::LengthPercentage,
+            b"color" => DataType::Color,
+            b"image" => DataType::Image,
+            b"url" => DataType::Url,
+            b"integer" => DataType::Integer,
+            b"angle" => DataType::Angle,
+            b"time" => DataType::Time,
+            b"resolution" => DataType::Resolution,
+            b"transform-function" => DataType::TransformFunction,
+            b"custom-ident" => DataType::CustomIdent,
+            b"transform-list" => DataType::TransformList,
+            b"string" => DataType::String,
+            _ => return None,
+        })
+    }
+
+    /// Returns true if this data type requires deferring computation to properly
+    /// resolve font-dependent lengths.
+    pub fn may_reference_font_relative_length(&self) -> bool {
+        match self {
+            DataType::Length |
+            DataType::LengthPercentage |
+            DataType::TransformFunction |
+            DataType::TransformList => true,
+            DataType::Number |
+            DataType::Percentage |
+            DataType::Color |
+            DataType::Image |
+            DataType::Url |
+            DataType::Integer |
+            DataType::Angle |
+            DataType::Time |
+            DataType::Resolution |
+            DataType::CustomIdent |
+            DataType::String => false,
+        }
+    }
+}
+
+impl ToCss for DataType {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
+        dest.write_char('<')?;
+        dest.write_str(match *self {
+            DataType::Length => "length",
+            DataType::Number => "number",
+            DataType::Percentage => "percentage",
+            DataType::LengthPercentage => "length-percentage",
+            DataType::Color => "color",
+            DataType::Image => "image",
+            DataType::Url => "url",
+            DataType::Integer => "integer",
+            DataType::Angle => "angle",
+            DataType::Time => "time",
+            DataType::Resolution => "resolution",
+            DataType::TransformFunction => "transform-function",
+            DataType::CustomIdent => "custom-ident",
+            DataType::TransformList => "transform-list",
+            DataType::String => "string",
+        })?;
+        dest.write_char('>')
+    }
+}