servo/components/selectors/tree.rs
Emilio Cobos Álvarez e3009a4de9
style: Implement shadow part forwarding (minus invalidation).
Some of the stuff, in particular inside GeckoBindings stuff should be
refactored to be less ugly and duplicate a bit less code, but the rest of the
code should be landable as is.

Some invalidation changes are already needed because we weren't matching with
the right shadow host during invalidation (which made existing ::part() tests
fail).

Pending invalidation work:

 * Making exportparts work right on the snapshots.
 * Invalidating parts from descendant hosts.

They're not very hard but I need to think how to best implement it:

 * Maybe get rid of ShadowRoot::mParts and just walk DOM descendants in the
   Shadow DOM.

 * Maybe implement a ElementHasExportPartsAttr much like HasPartAttr and use
   that to keep the list of elements.

 * Maybe invalidate :host and ::part() together in here[1]

 * Maybe something else.

Opinions?

[1]: https://searchfox.org/mozilla-central/rev/131338e5017bc0283d86fb73844407b9a2155c98/servo/components/style/invalidation/element/invalidator.rs#561

Differential Revision: https://phabricator.services.mozilla.com/D53730
2019-11-30 20:45:03 +01:00

154 lines
5.1 KiB
Rust

/* 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/. */
//! Traits that nodes must implement. Breaks the otherwise-cyclic dependency
//! between layout and style.
use crate::attr::{AttrSelectorOperation, CaseSensitivity, NamespaceConstraint};
use crate::matching::{ElementSelectorFlags, MatchingContext};
use crate::parser::SelectorImpl;
use std::fmt::Debug;
use std::ptr::NonNull;
/// Opaque representation of an Element, for identity comparisons.
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub struct OpaqueElement(NonNull<()>);
unsafe impl Send for OpaqueElement {}
impl OpaqueElement {
/// Creates a new OpaqueElement from an arbitrarily-typed pointer.
pub fn new<T>(ptr: &T) -> Self {
unsafe {
OpaqueElement(NonNull::new_unchecked(
ptr as *const T as *const () as *mut (),
))
}
}
}
pub trait Element: Sized + Clone + Debug {
type Impl: SelectorImpl;
/// Converts self into an opaque representation.
fn opaque(&self) -> OpaqueElement;
fn parent_element(&self) -> Option<Self>;
/// Whether the parent node of this element is a shadow root.
fn parent_node_is_shadow_root(&self) -> bool;
/// The host of the containing shadow root, if any.
fn containing_shadow_host(&self) -> Option<Self>;
/// The parent of a given pseudo-element, after matching a pseudo-element
/// selector.
///
/// This is guaranteed to be called in a pseudo-element.
fn pseudo_element_originating_element(&self) -> Option<Self> {
debug_assert!(self.is_pseudo_element());
self.parent_element()
}
/// Whether we're matching on a pseudo-element.
fn is_pseudo_element(&self) -> bool;
/// Skips non-element nodes
fn prev_sibling_element(&self) -> Option<Self>;
/// Skips non-element nodes
fn next_sibling_element(&self) -> Option<Self>;
fn is_html_element_in_html_document(&self) -> bool;
fn has_local_name(&self, local_name: &<Self::Impl as SelectorImpl>::BorrowedLocalName) -> bool;
/// Empty string for no namespace
fn has_namespace(&self, ns: &<Self::Impl as SelectorImpl>::BorrowedNamespaceUrl) -> bool;
/// Whether this element and the `other` element have the same local name and namespace.
fn is_same_type(&self, other: &Self) -> bool;
fn attr_matches(
&self,
ns: &NamespaceConstraint<&<Self::Impl as SelectorImpl>::NamespaceUrl>,
local_name: &<Self::Impl as SelectorImpl>::LocalName,
operation: &AttrSelectorOperation<&<Self::Impl as SelectorImpl>::AttrValue>,
) -> bool;
fn match_non_ts_pseudo_class<F>(
&self,
pc: &<Self::Impl as SelectorImpl>::NonTSPseudoClass,
context: &mut MatchingContext<Self::Impl>,
flags_setter: &mut F,
) -> bool
where
F: FnMut(&Self, ElementSelectorFlags);
fn match_pseudo_element(
&self,
pe: &<Self::Impl as SelectorImpl>::PseudoElement,
context: &mut MatchingContext<Self::Impl>,
) -> bool;
/// Whether this element is a `link`.
fn is_link(&self) -> bool;
/// Returns whether the element is an HTML <slot> element.
fn is_html_slot_element(&self) -> bool;
/// Returns the assigned <slot> element this element is assigned to.
///
/// Necessary for the `::slotted` pseudo-class.
fn assigned_slot(&self) -> Option<Self> {
None
}
fn has_id(
&self,
id: &<Self::Impl as SelectorImpl>::Identifier,
case_sensitivity: CaseSensitivity,
) -> bool;
fn has_class(
&self,
name: &<Self::Impl as SelectorImpl>::ClassName,
case_sensitivity: CaseSensitivity,
) -> bool;
/// Returns the mapping from the `exportparts` attribute in the regular
/// direction, that is, inner-tree -> outer-tree.
fn exported_part(
&self,
name: &<Self::Impl as SelectorImpl>::PartName,
) -> Option<<Self::Impl as SelectorImpl>::PartName>;
/// Returns the mapping from the `exportparts` attribute in the reverse
/// direction, that is, in an outer-tree -> inner-tree direction.
fn imported_part(
&self,
name: &<Self::Impl as SelectorImpl>::PartName,
) -> Option<<Self::Impl as SelectorImpl>::PartName>;
fn is_part(&self, name: &<Self::Impl as SelectorImpl>::PartName) -> bool;
/// Returns whether this element matches `:empty`.
///
/// That is, whether it does not contain any child element or any non-zero-length text node.
/// See http://dev.w3.org/csswg/selectors-3/#empty-pseudo
fn is_empty(&self) -> bool;
/// Returns whether this element matches `:root`,
/// i.e. whether it is the root element of a document.
///
/// Note: this can be false even if `.parent_element()` is `None`
/// if the parent node is a `DocumentFragment`.
fn is_root(&self) -> bool;
/// Returns whether this element should ignore matching nth child
/// selector.
fn ignores_nth_child_selectors(&self) -> bool {
false
}
}