1 files changed, 261 insertions, 0 deletions
diff --git a/servo/components/style/values/generics/font.rs b/servo/components/style/values/generics/font.rs
new file mode 100644
index 0000000000..a88df7be17
--- /dev/null
+++ b/servo/components/style/values/generics/font.rs
@@ -0,0 +1,261 @@
+/* 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/. */
+
+//! Generic types for font stuff.
+
+use crate::parser::{Parse, ParserContext};
+use crate::One;
+use byteorder::{BigEndian, ReadBytesExt};
+use cssparser::Parser;
+use std::fmt::{self, Write};
+use std::io::Cursor;
+use style_traits::{CssWriter, ParseError};
+use style_traits::{StyleParseErrorKind, ToCss};
+
+/// https://drafts.csswg.org/css-fonts-4/#feature-tag-value
+#[derive(
+    Clone,
+    Debug,
+    Eq,
+    MallocSizeOf,
+    PartialEq,
+    SpecifiedValueInfo,
+    ToComputedValue,
+    ToResolvedValue,
+    ToShmem,
+)]
+pub struct FeatureTagValue<Integer> {
+    /// A four-character tag, packed into a u32 (one byte per character).
+    pub tag: FontTag,
+    /// The actual value.
+    pub value: Integer,
+}
+
+impl<Integer> ToCss for FeatureTagValue<Integer>
+where
+    Integer: One + ToCss + PartialEq,
+{
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
+        self.tag.to_css(dest)?;
+        // Don't serialize the default value.
+        if !self.value.is_one() {
+            dest.write_char(' ')?;
+            self.value.to_css(dest)?;
+        }
+
+        Ok(())
+    }
+}
+
+/// Variation setting for a single feature, see:
+///
+/// https://drafts.csswg.org/css-fonts-4/#font-variation-settings-def
+#[derive(
+    Animate,
+    Clone,
+    ComputeSquaredDistance,
+    Debug,
+    Eq,
+    MallocSizeOf,
+    PartialEq,
+    SpecifiedValueInfo,
+    ToComputedValue,
+    ToCss,
+    ToResolvedValue,
+    ToShmem,
+)]
+pub struct VariationValue<Number> {
+    /// A four-character tag, packed into a u32 (one byte per character).
+    #[animation(constant)]
+    pub tag: FontTag,
+    /// The actual value.
+    pub value: Number,
+}
+
+/// A value both for font-variation-settings and font-feature-settings.
+#[derive(
+    Clone,
+    Debug,
+    Eq,
+    MallocSizeOf,
+    PartialEq,
+    SpecifiedValueInfo,
+    ToComputedValue,
+    ToCss,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[css(comma)]
+pub struct FontSettings<T>(#[css(if_empty = "normal", iterable)] pub Box<[T]>);
+
+impl<T> FontSettings<T> {
+    /// Default value of font settings as `normal`.
+    #[inline]
+    pub fn normal() -> Self {
+        FontSettings(vec![].into_boxed_slice())
+    }
+}
+
+impl<T: Parse> Parse for FontSettings<T> {
+    /// https://drafts.csswg.org/css-fonts-4/#descdef-font-face-font-feature-settings
+    /// https://drafts.csswg.org/css-fonts-4/#font-variation-settings-def
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        if input
+            .try_parse(|i| i.expect_ident_matching("normal"))
+            .is_ok()
+        {
+            return Ok(Self::normal());
+        }
+
+        Ok(FontSettings(
+            input
+                .parse_comma_separated(|i| T::parse(context, i))?
+                .into_boxed_slice(),
+        ))
+    }
+}
+
+/// A font four-character tag, represented as a u32 for convenience.
+///
+/// See:
+///   https://drafts.csswg.org/css-fonts-4/#font-variation-settings-def
+///   https://drafts.csswg.org/css-fonts-4/#descdef-font-face-font-feature-settings
+///
+#[derive(
+    Clone,
+    Copy,
+    Debug,
+    Eq,
+    MallocSizeOf,
+    PartialEq,
+    SpecifiedValueInfo,
+    ToComputedValue,
+    ToResolvedValue,
+    ToShmem,
+)]
+pub struct FontTag(pub u32);
+
+impl ToCss for FontTag {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
+        use byteorder::ByteOrder;
+        use std::str;
+
+        let mut raw = [0u8; 4];
+        BigEndian::write_u32(&mut raw, self.0);
+        str::from_utf8(&raw).unwrap_or_default().to_css(dest)
+    }
+}
+
+impl Parse for FontTag {
+    fn parse<'i, 't>(
+        _context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        let location = input.current_source_location();
+        let tag = input.expect_string()?;
+
+        // allowed strings of length 4 containing chars: <U+20, U+7E>
+        if tag.len() != 4 || tag.as_bytes().iter().any(|c| *c < b' ' || *c > b'~') {
+            return Err(location.new_custom_error(StyleParseErrorKind::UnspecifiedError));
+        }
+
+        let mut raw = Cursor::new(tag.as_bytes());
+        Ok(FontTag(raw.read_u32::<BigEndian>().unwrap()))
+    }
+}
+
+/// A generic value for the `font-style` property.
+///
+/// https://drafts.csswg.org/css-fonts-4/#font-style-prop
+#[allow(missing_docs)]
+#[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
+#[derive(
+    Animate,
+    Clone,
+    ComputeSquaredDistance,
+    Copy,
+    Debug,
+    Hash,
+    MallocSizeOf,
+    PartialEq,
+    SpecifiedValueInfo,
+    ToAnimatedValue,
+    ToAnimatedZero,
+    ToResolvedValue,
+    ToShmem,
+)]
+pub enum FontStyle<Angle> {
+    #[animation(error)]
+    Normal,
+    #[animation(error)]
+    Italic,
+    #[value_info(starts_with_keyword)]
+    Oblique(Angle),
+}
+
+/// A generic value for the `font-size-adjust` property.
+///
+/// https://www.w3.org/TR/css-fonts-4/#font-size-adjust-prop
+/// https://github.com/w3c/csswg-drafts/issues/6160
+/// https://github.com/w3c/csswg-drafts/issues/6288
+#[allow(missing_docs)]
+#[repr(u8)]
+#[derive(
+    Animate,
+    Clone,
+    ComputeSquaredDistance,
+    Copy,
+    Debug,
+    Hash,
+    MallocSizeOf,
+    PartialEq,
+    SpecifiedValueInfo,
+    ToAnimatedValue,
+    ToAnimatedZero,
+    ToComputedValue,
+    ToResolvedValue,
+    ToShmem,
+)]
+pub enum GenericFontSizeAdjust<Number> {
+    #[animation(error)]
+    None,
+    // 'ex-height' is the implied basis, so the keyword can be omitted
+    ExHeight(Number),
+    #[value_info(starts_with_keyword)]
+    CapHeight(Number),
+    #[value_info(starts_with_keyword)]
+    ChWidth(Number),
+    #[value_info(starts_with_keyword)]
+    IcWidth(Number),
+    #[value_info(starts_with_keyword)]
+    IcHeight(Number),
+}
+
+impl<Number: ToCss> ToCss for GenericFontSizeAdjust<Number> {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
+        let (prefix, value) = match self {
+            Self::None => return dest.write_str("none"),
+            Self::ExHeight(v) => ("", v),
+            Self::CapHeight(v) => ("cap-height ", v),
+            Self::ChWidth(v) => ("ch-width ", v),
+            Self::IcWidth(v) => ("ic-width ", v),
+            Self::IcHeight(v) => ("ic-height ", v),
+        };
+
+        dest.write_str(prefix)?;
+        value.to_css(dest)
+    }
+}