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Diffstat (limited to 'servo/components/style/selector_parser.rs')
-rw-r--r-- | servo/components/style/selector_parser.rs | 240 |
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..a6b02a6e85 --- /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::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)) + } + + /// 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) + } +} |