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style: Implement a more fine-grained invalidation method.
This commit also removes the old restyle_hints module and splits it into multiple modules under components/style/invalidation/element/. The basic approach is to walk down the tree using compound selectors as needed, in order to do as little selector-matching as possible. Bug: 1368240 MozReview-Commit-ID: 2YO8fKFygZI
This commit is contained in:
Emilio Cobos Álvarez
parent
fd10729941
commit
cb06375fe2
21 changed files with 1673 additions and 1486 deletions
341
components/style/invalidation/element/element_wrapper.rs
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341
components/style/invalidation/element/element_wrapper.rs
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@ -0,0 +1,341 @@
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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//! A wrapper over an element and a snapshot, that allows us to selector-match
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//! against a past state of the element.
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use {Atom, CaseSensitivityExt, LocalName, Namespace};
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use dom::TElement;
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use element_state::ElementState;
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use selector_parser::{NonTSPseudoClass, PseudoElement, SelectorImpl, Snapshot, SnapshotMap, AttrValue};
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use selectors::Element;
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use selectors::attr::{AttrSelectorOperation, CaseSensitivity, NamespaceConstraint};
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use selectors::matching::{ElementSelectorFlags, LocalMatchingContext, MatchingContext};
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use selectors::matching::RelevantLinkStatus;
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use std::cell::Cell;
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use std::fmt;
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/// In order to compute restyle hints, we perform a selector match against a
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/// list of partial selectors whose rightmost simple selector may be sensitive
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/// to the thing being changed. We do this matching twice, once for the element
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/// as it exists now and once for the element as it existed at the time of the
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/// last restyle. If the results of the selector match differ, that means that
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/// the given partial selector is sensitive to the change, and we compute a
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/// restyle hint based on its combinator.
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///
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/// In order to run selector matching against the old element state, we generate
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/// a wrapper for the element which claims to have the old state. This is the
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/// ElementWrapper logic below.
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///
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/// Gecko does this differently for element states, and passes a mask called
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/// mStateMask, which indicates the states that need to be ignored during
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/// selector matching. This saves an ElementWrapper allocation and an additional
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/// selector match call at the expense of additional complexity inside the
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/// selector matching logic. This only works for boolean states though, so we
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/// still need to take the ElementWrapper approach for attribute-dependent
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/// style. So we do it the same both ways for now to reduce complexity, but it's
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/// worth measuring the performance impact (if any) of the mStateMask approach.
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pub trait ElementSnapshot : Sized {
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/// The state of the snapshot, if any.
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fn state(&self) -> Option<ElementState>;
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/// If this snapshot contains attribute information.
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fn has_attrs(&self) -> bool;
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/// The ID attribute per this snapshot. Should only be called if
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/// `has_attrs()` returns true.
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fn id_attr(&self) -> Option<Atom>;
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/// Whether this snapshot contains the class `name`. Should only be called
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/// if `has_attrs()` returns true.
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fn has_class(&self, name: &Atom, case_sensitivity: CaseSensitivity) -> bool;
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/// A callback that should be called for each class of the snapshot. Should
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/// only be called if `has_attrs()` returns true.
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fn each_class<F>(&self, F)
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where F: FnMut(&Atom);
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/// The `xml:lang=""` or `lang=""` attribute value per this snapshot.
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fn lang_attr(&self) -> Option<AttrValue>;
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}
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/// A simple wrapper over an element and a snapshot, that allows us to
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/// selector-match against a past state of the element.
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#[derive(Clone)]
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pub struct ElementWrapper<'a, E>
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where E: TElement,
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{
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element: E,
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cached_snapshot: Cell<Option<&'a Snapshot>>,
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snapshot_map: &'a SnapshotMap,
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}
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impl<'a, E> ElementWrapper<'a, E>
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where E: TElement,
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{
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/// Trivially constructs an `ElementWrapper`.
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pub fn new(el: E, snapshot_map: &'a SnapshotMap) -> Self {
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ElementWrapper {
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element: el,
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cached_snapshot: Cell::new(None),
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snapshot_map: snapshot_map,
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}
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}
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/// Gets the snapshot associated with this element, if any.
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pub fn snapshot(&self) -> Option<&'a Snapshot> {
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if !self.element.has_snapshot() {
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return None;
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}
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if let Some(s) = self.cached_snapshot.get() {
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return Some(s);
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}
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let snapshot = self.snapshot_map.get(&self.element);
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debug_assert!(snapshot.is_some(), "has_snapshot lied!");
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self.cached_snapshot.set(snapshot);
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snapshot
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}
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/// Returns the states that have changed since the element was snapshotted.
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pub fn state_changes(&self) -> ElementState {
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let snapshot = match self.snapshot() {
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Some(s) => s,
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None => return ElementState::empty(),
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};
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match snapshot.state() {
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Some(state) => state ^ self.element.get_state(),
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None => ElementState::empty(),
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}
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}
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/// Returns the value of the `xml:lang=""` (or, if appropriate, `lang=""`)
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/// attribute from this element's snapshot or the closest ancestor
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/// element snapshot with the attribute specified.
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fn get_lang(&self) -> Option<AttrValue> {
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let mut current = self.clone();
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loop {
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let lang = match self.snapshot() {
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Some(snapshot) if snapshot.has_attrs() => snapshot.lang_attr(),
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_ => current.element.lang_attr(),
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};
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if lang.is_some() {
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return lang;
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}
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match current.parent_element() {
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Some(parent) => current = parent,
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None => return None,
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}
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}
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}
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}
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impl<'a, E> fmt::Debug for ElementWrapper<'a, E>
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where E: TElement,
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{
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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// Ignore other fields for now, can change later if needed.
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self.element.fmt(f)
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}
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}
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impl<'a, E> Element for ElementWrapper<'a, E>
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where E: TElement,
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{
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type Impl = SelectorImpl;
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fn match_non_ts_pseudo_class<F>(&self,
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pseudo_class: &NonTSPseudoClass,
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context: &mut LocalMatchingContext<Self::Impl>,
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relevant_link: &RelevantLinkStatus,
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_setter: &mut F)
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-> bool
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where F: FnMut(&Self, ElementSelectorFlags),
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{
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// Some pseudo-classes need special handling to evaluate them against
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// the snapshot.
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match *pseudo_class {
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#[cfg(feature = "gecko")]
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NonTSPseudoClass::MozAny(ref selectors) => {
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use selectors::matching::matches_complex_selector;
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return selectors.iter().any(|s| {
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matches_complex_selector(s.iter(), self, context, _setter)
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})
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}
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// :dir is implemented in terms of state flags, but which state flag
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// it maps to depends on the argument to :dir. That means we can't
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// just add its state flags to the NonTSPseudoClass, because if we
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// added all of them there, and tested via intersects() here, we'd
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// get incorrect behavior for :not(:dir()) cases.
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//
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// FIXME(bz): How can I set this up so once Servo adds :dir()
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// support we don't forget to update this code?
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#[cfg(feature = "gecko")]
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NonTSPseudoClass::Dir(ref s) => {
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use invalidation::element::invalidation_map::dir_selector_to_state;
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let selector_flag = dir_selector_to_state(s);
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if selector_flag.is_empty() {
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// :dir() with some random argument; does not match.
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return false;
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}
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let state = match self.snapshot().and_then(|s| s.state()) {
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Some(snapshot_state) => snapshot_state,
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None => self.element.get_state(),
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};
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return state.contains(selector_flag);
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}
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// For :link and :visited, we don't actually want to test the element
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// state directly. Instead, we use the `relevant_link` to determine if
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// they match.
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NonTSPseudoClass::Link => {
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return relevant_link.is_unvisited(self, context.shared);
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}
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NonTSPseudoClass::Visited => {
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return relevant_link.is_visited(self, context.shared);
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}
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#[cfg(feature = "gecko")]
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NonTSPseudoClass::MozTableBorderNonzero => {
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if let Some(snapshot) = self.snapshot() {
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if snapshot.has_other_pseudo_class_state() {
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return snapshot.mIsTableBorderNonzero();
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}
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}
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}
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#[cfg(feature = "gecko")]
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NonTSPseudoClass::MozBrowserFrame => {
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if let Some(snapshot) = self.snapshot() {
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if snapshot.has_other_pseudo_class_state() {
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return snapshot.mIsMozBrowserFrame();
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}
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}
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}
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// :lang() needs to match using the closest ancestor xml:lang="" or
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// lang="" attribtue from snapshots.
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NonTSPseudoClass::Lang(ref lang_arg) => {
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return self.element.match_element_lang(Some(self.get_lang()), lang_arg);
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}
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_ => {}
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}
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let flag = pseudo_class.state_flag();
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if flag.is_empty() {
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return self.element.match_non_ts_pseudo_class(pseudo_class,
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context,
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relevant_link,
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&mut |_, _| {})
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}
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match self.snapshot().and_then(|s| s.state()) {
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Some(snapshot_state) => snapshot_state.intersects(flag),
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None => {
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self.element.match_non_ts_pseudo_class(pseudo_class,
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context,
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relevant_link,
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&mut |_, _| {})
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}
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}
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}
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fn match_pseudo_element(&self,
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pseudo_element: &PseudoElement,
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context: &mut MatchingContext)
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-> bool
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{
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self.element.match_pseudo_element(pseudo_element, context)
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}
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fn is_link(&self) -> bool {
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self.element.is_link()
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}
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fn parent_element(&self) -> Option<Self> {
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self.element.parent_element()
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.map(|e| ElementWrapper::new(e, self.snapshot_map))
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}
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fn first_child_element(&self) -> Option<Self> {
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self.element.first_child_element()
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.map(|e| ElementWrapper::new(e, self.snapshot_map))
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}
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fn last_child_element(&self) -> Option<Self> {
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self.element.last_child_element()
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.map(|e| ElementWrapper::new(e, self.snapshot_map))
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}
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fn prev_sibling_element(&self) -> Option<Self> {
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self.element.prev_sibling_element()
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.map(|e| ElementWrapper::new(e, self.snapshot_map))
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}
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fn next_sibling_element(&self) -> Option<Self> {
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self.element.next_sibling_element()
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.map(|e| ElementWrapper::new(e, self.snapshot_map))
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}
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fn is_html_element_in_html_document(&self) -> bool {
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self.element.is_html_element_in_html_document()
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}
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fn get_local_name(&self) -> &<Self::Impl as ::selectors::SelectorImpl>::BorrowedLocalName {
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self.element.get_local_name()
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}
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fn get_namespace(&self) -> &<Self::Impl as ::selectors::SelectorImpl>::BorrowedNamespaceUrl {
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self.element.get_namespace()
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}
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fn attr_matches(&self,
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ns: &NamespaceConstraint<&Namespace>,
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local_name: &LocalName,
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operation: &AttrSelectorOperation<&AttrValue>)
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-> bool {
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match self.snapshot() {
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Some(snapshot) if snapshot.has_attrs() => {
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snapshot.attr_matches(ns, local_name, operation)
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}
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_ => self.element.attr_matches(ns, local_name, operation)
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}
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}
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fn has_id(&self, id: &Atom, case_sensitivity: CaseSensitivity) -> bool {
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match self.snapshot() {
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Some(snapshot) if snapshot.has_attrs() => {
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snapshot.id_attr().map_or(false, |atom| case_sensitivity.eq_atom(&atom, id))
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}
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_ => self.element.has_id(id, case_sensitivity)
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}
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}
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fn has_class(&self, name: &Atom, case_sensitivity: CaseSensitivity) -> bool {
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match self.snapshot() {
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Some(snapshot) if snapshot.has_attrs() => {
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snapshot.has_class(name, case_sensitivity)
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}
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_ => self.element.has_class(name, case_sensitivity)
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}
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}
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fn is_empty(&self) -> bool {
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self.element.is_empty()
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}
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fn is_root(&self) -> bool {
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self.element.is_root()
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}
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fn pseudo_element_originating_element(&self) -> Option<Self> {
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self.element.closest_non_native_anonymous_ancestor()
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.map(|e| ElementWrapper::new(e, self.snapshot_map))
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}
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}
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