1 files changed, 240 insertions, 0 deletions
diff --git a/servo/components/style/selector_parser.rs b/servo/components/style/selector_parser.rs
new file mode 100644
index 0000000000..4eef26f1b7
--- /dev/null
+++ b/servo/components/style/selector_parser.rs
@@ -0,0 +1,240 @@
+/* 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/. */
+
+//! The pseudo-classes and pseudo-elements supported by the style system.
+
+#![deny(missing_docs)]
+
+use crate::stylesheets::{Namespaces, Origin, UrlExtraData};
+use crate::values::serialize_atom_identifier;
+use crate::Atom;
+use cssparser::{Parser as CssParser, ParserInput};
+use dom::ElementState;
+use selectors::parser::{ParseRelative, SelectorList};
+use std::fmt::{self, Debug, Write};
+use style_traits::{CssWriter, ParseError, ToCss};
+
+/// A convenient alias for the type that represents an attribute value used for
+/// selector parser implementation.
+pub type AttrValue = <SelectorImpl as ::selectors::SelectorImpl>::AttrValue;
+
+#[cfg(feature = "servo")]
+pub use crate::servo::selector_parser::*;
+
+#[cfg(feature = "gecko")]
+pub use crate::gecko::selector_parser::*;
+
+#[cfg(feature = "servo")]
+pub use crate::servo::selector_parser::ServoElementSnapshot as Snapshot;
+
+#[cfg(feature = "gecko")]
+pub use crate::gecko::snapshot::GeckoElementSnapshot as Snapshot;
+
+#[cfg(feature = "servo")]
+pub use crate::servo::restyle_damage::ServoRestyleDamage as RestyleDamage;
+
+#[cfg(feature = "gecko")]
+pub use crate::gecko::restyle_damage::GeckoRestyleDamage as RestyleDamage;
+
+/// Servo's selector parser.
+#[cfg_attr(feature = "servo", derive(MallocSizeOf))]
+pub struct SelectorParser<'a> {
+    /// The origin of the stylesheet we're parsing.
+    pub stylesheet_origin: Origin,
+    /// The namespace set of the stylesheet.
+    pub namespaces: &'a Namespaces,
+    /// The extra URL data of the stylesheet, which is used to look up
+    /// whether we are parsing a chrome:// URL style sheet.
+    pub url_data: &'a UrlExtraData,
+    /// Whether we're parsing selectors for `@supports`
+    pub for_supports_rule: bool,
+}
+
+impl<'a> SelectorParser<'a> {
+    /// Parse a selector list with an author origin and without taking into
+    /// account namespaces.
+    ///
+    /// This is used for some DOM APIs like `querySelector`.
+    pub fn parse_author_origin_no_namespace<'i>(
+        input: &'i str,
+        url_data: &UrlExtraData,
+    ) -> Result<SelectorList<SelectorImpl>, ParseError<'i>> {
+        let namespaces = Namespaces::default();
+        let parser = SelectorParser {
+            stylesheet_origin: Origin::Author,
+            namespaces: &namespaces,
+            url_data,
+            for_supports_rule: false,
+        };
+        let mut input = ParserInput::new(input);
+        SelectorList::parse(&parser, &mut CssParser::new(&mut input), ParseRelative::No)
+    }
+
+    /// Whether we're parsing selectors in a user-agent stylesheet.
+    pub fn in_user_agent_stylesheet(&self) -> bool {
+        matches!(self.stylesheet_origin, Origin::UserAgent)
+    }
+
+    /// Whether we're parsing selectors in a stylesheet that has chrome
+    /// privilege.
+    pub fn chrome_rules_enabled(&self) -> bool {
+        self.url_data.chrome_rules_enabled() || self.stylesheet_origin == Origin::User
+    }
+}
+
+/// This enumeration determines if a pseudo-element is eagerly cascaded or not.
+///
+/// If you're implementing a public selector for `Servo` that the end-user might
+/// customize, then you probably need to make it eager.
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub enum PseudoElementCascadeType {
+    /// Eagerly cascaded pseudo-elements are "normal" pseudo-elements (i.e.
+    /// `::before` and `::after`). They inherit styles normally as another
+    /// selector would do, and they're computed as part of the cascade.
+    Eager,
+    /// Lazy pseudo-elements are affected by selector matching, but they're only
+    /// computed when needed, and not before. They're useful for general
+    /// pseudo-elements that are not very common.
+    ///
+    /// Note that in Servo lazy pseudo-elements are restricted to a subset of
+    /// selectors, so you can't use it for public pseudo-elements. This is not
+    /// the case with Gecko though.
+    Lazy,
+    /// Precomputed pseudo-elements skip the cascade process entirely, mostly as
+    /// an optimisation since they are private pseudo-elements (like
+    /// `::-servo-details-content`).
+    ///
+    /// This pseudo-elements are resolved on the fly using *only* global rules
+    /// (rules of the form `*|*`), and applying them to the parent style.
+    Precomputed,
+}
+
+/// A per-pseudo map, from a given pseudo to a `T`.
+#[derive(Clone, MallocSizeOf)]
+pub struct PerPseudoElementMap<T> {
+    entries: [Option<T>; PSEUDO_COUNT],
+}
+
+impl<T> Default for PerPseudoElementMap<T> {
+    fn default() -> Self {
+        Self {
+            entries: PseudoElement::pseudo_none_array(),
+        }
+    }
+}
+
+impl<T> Debug for PerPseudoElementMap<T>
+where
+    T: Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_char('[')?;
+        let mut first = true;
+        for entry in self.entries.iter() {
+            if !first {
+                f.write_str(", ")?;
+            }
+            first = false;
+            entry.fmt(f)?;
+        }
+        f.write_char(']')
+    }
+}
+
+impl<T> PerPseudoElementMap<T> {
+    /// Get an entry in the map.
+    pub fn get(&self, pseudo: &PseudoElement) -> Option<&T> {
+        self.entries[pseudo.index()].as_ref()
+    }
+
+    /// Clear this enumerated array.
+    pub fn clear(&mut self) {
+        *self = Self::default();
+    }
+
+    /// Set an entry value.
+    ///
+    /// Returns an error if the element is not a simple pseudo.
+    pub fn set(&mut self, pseudo: &PseudoElement, value: T) {
+        self.entries[pseudo.index()] = Some(value);
+    }
+
+    /// Get an entry for `pseudo`, or create it with calling `f`.
+    pub fn get_or_insert_with<F>(&mut self, pseudo: &PseudoElement, f: F) -> &mut T
+    where
+        F: FnOnce() -> T,
+    {
+        let index = pseudo.index();
+        if self.entries[index].is_none() {
+            self.entries[index] = Some(f());
+        }
+        self.entries[index].as_mut().unwrap()
+    }
+
+    /// Get an iterator for the entries.
+    pub fn iter(&self) -> std::slice::Iter<Option<T>> {
+        self.entries.iter()
+    }
+
+    /// Get a mutable iterator for the entries.
+    pub fn iter_mut(&mut self) -> std::slice::IterMut<Option<T>> {
+        self.entries.iter_mut()
+    }
+}
+
+/// Values for the :dir() pseudo class
+///
+/// "ltr" and "rtl" values are normalized to lowercase.
+#[derive(Clone, Debug, Eq, MallocSizeOf, PartialEq, ToShmem)]
+pub struct Direction(pub Atom);
+
+/// Horizontal values for the :dir() pseudo class
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub enum HorizontalDirection {
+    /// :dir(ltr)
+    Ltr,
+    /// :dir(rtl)
+    Rtl,
+}
+
+impl Direction {
+    /// Parse a direction value.
+    pub fn parse<'i, 't>(parser: &mut CssParser<'i, 't>) -> Result<Self, ParseError<'i>> {
+        let ident = parser.expect_ident()?;
+        Ok(Direction(match_ignore_ascii_case! { &ident,
+            "rtl" => atom!("rtl"),
+            "ltr" => atom!("ltr"),
+            _ => Atom::from(ident.as_ref()),
+        }))
+    }
+
+    /// Convert this Direction into a HorizontalDirection, if applicable
+    pub fn as_horizontal_direction(&self) -> Option<HorizontalDirection> {
+        if self.0 == atom!("ltr") {
+            Some(HorizontalDirection::Ltr)
+        } else if self.0 == atom!("rtl") {
+            Some(HorizontalDirection::Rtl)
+        } else {
+            None
+        }
+    }
+
+    /// Gets the element state relevant to this :dir() selector.
+    pub fn element_state(&self) -> ElementState {
+        match self.as_horizontal_direction() {
+            Some(HorizontalDirection::Ltr) => ElementState::LTR,
+            Some(HorizontalDirection::Rtl) => ElementState::RTL,
+            None => ElementState::empty(),
+        }
+    }
+}
+
+impl ToCss for Direction {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
+        serialize_atom_identifier(&self.0, dest)
+    }
+}