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Diffstat (limited to 'servo/components/style/invalidation/stylesheets.rs')
| -rw-r--r-- | servo/components/style/invalidation/stylesheets.rs | 651 |
1 files changed, 651 insertions, 0 deletions
diff --git a/servo/components/style/invalidation/stylesheets.rs b/servo/components/style/invalidation/stylesheets.rs new file mode 100644 index 0000000000..d845897aa4 --- /dev/null +++ b/servo/components/style/invalidation/stylesheets.rs @@ -0,0 +1,651 @@ +/* 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/. */ + +//! A collection of invalidations due to changes in which stylesheets affect a +//! document. + +#![deny(unsafe_code)] + +use crate::context::QuirksMode; +use crate::dom::{TDocument, TElement, TNode}; +use crate::invalidation::element::element_wrapper::{ElementSnapshot, ElementWrapper}; +use crate::invalidation::element::restyle_hints::RestyleHint; +use crate::media_queries::Device; +use crate::selector_map::{MaybeCaseInsensitiveHashMap, PrecomputedHashMap}; +use crate::selector_parser::{SelectorImpl, Snapshot, SnapshotMap}; +use crate::shared_lock::SharedRwLockReadGuard; +use crate::stylesheets::{CssRule, StylesheetInDocument}; +use crate::stylesheets::{EffectiveRules, EffectiveRulesIterator}; +use crate::values::AtomIdent; +use crate::LocalName as SelectorLocalName; +use crate::{Atom, ShrinkIfNeeded}; +use selectors::parser::{Component, LocalName, Selector}; + +/// The kind of change that happened for a given rule. +#[repr(u32)] +#[derive(Clone, Copy, Debug, Eq, Hash, MallocSizeOf, PartialEq)] +pub enum RuleChangeKind { + /// The rule was inserted. + Insertion, + /// The rule was removed. + Removal, + /// Some change in the rule which we don't know about, and could have made + /// the rule change in any way. + Generic, + /// A change in the declarations of a style rule. + StyleRuleDeclarations, +} + +/// A style sheet invalidation represents a kind of element or subtree that may +/// need to be restyled. Whether it represents a whole subtree or just a single +/// element is determined by the given InvalidationKind in +/// StylesheetInvalidationSet's maps. +#[derive(Debug, Eq, Hash, MallocSizeOf, PartialEq)] +enum Invalidation { + /// An element with a given id. + ID(AtomIdent), + /// An element with a given class name. + Class(AtomIdent), + /// An element with a given local name. + LocalName { + name: SelectorLocalName, + lower_name: SelectorLocalName, + }, +} + +impl Invalidation { + fn is_id(&self) -> bool { + matches!(*self, Invalidation::ID(..)) + } + + fn is_id_or_class(&self) -> bool { + matches!(*self, Invalidation::ID(..) | Invalidation::Class(..)) + } +} + +/// Whether we should invalidate just the element, or the whole subtree within +/// it. +#[derive(Clone, Copy, Debug, Eq, MallocSizeOf, Ord, PartialEq, PartialOrd)] +enum InvalidationKind { + None = 0, + Element, + Scope, +} + +impl std::ops::BitOrAssign for InvalidationKind { + #[inline] + fn bitor_assign(&mut self, other: Self) { + *self = std::cmp::max(*self, other); + } +} + +impl InvalidationKind { + #[inline] + fn is_scope(self) -> bool { + matches!(self, Self::Scope) + } + + #[inline] + fn add(&mut self, other: Option<&InvalidationKind>) { + if let Some(other) = other { + *self |= *other; + } + } +} + +/// A set of invalidations due to stylesheet additions. +/// +/// TODO(emilio): We might be able to do the same analysis for media query +/// changes too (or even selector changes?). +#[derive(Debug, Default, MallocSizeOf)] +pub struct StylesheetInvalidationSet { + classes: MaybeCaseInsensitiveHashMap<Atom, InvalidationKind>, + ids: MaybeCaseInsensitiveHashMap<Atom, InvalidationKind>, + local_names: PrecomputedHashMap<SelectorLocalName, InvalidationKind>, + fully_invalid: bool, +} + +impl StylesheetInvalidationSet { + /// Create an empty `StylesheetInvalidationSet`. + pub fn new() -> Self { + Default::default() + } + + /// Mark the DOM tree styles' as fully invalid. + pub fn invalidate_fully(&mut self) { + debug!("StylesheetInvalidationSet::invalidate_fully"); + self.clear(); + self.fully_invalid = true; + } + + fn shrink_if_needed(&mut self) { + if self.fully_invalid { + return; + } + self.classes.shrink_if_needed(); + self.ids.shrink_if_needed(); + self.local_names.shrink_if_needed(); + } + + /// Analyze the given stylesheet, and collect invalidations from their + /// rules, in order to avoid doing a full restyle when we style the document + /// next time. + pub fn collect_invalidations_for<S>( + &mut self, + device: &Device, + stylesheet: &S, + guard: &SharedRwLockReadGuard, + ) where + S: StylesheetInDocument, + { + debug!("StylesheetInvalidationSet::collect_invalidations_for"); + if self.fully_invalid { + debug!(" > Fully invalid already"); + return; + } + + if !stylesheet.enabled() || !stylesheet.is_effective_for_device(device, guard) { + debug!(" > Stylesheet was not effective"); + return; // Nothing to do here. + } + + let quirks_mode = device.quirks_mode(); + for rule in stylesheet.effective_rules(device, guard) { + self.collect_invalidations_for_rule( + rule, + guard, + device, + quirks_mode, + /* is_generic_change = */ false, + ); + if self.fully_invalid { + break; + } + } + + self.shrink_if_needed(); + + debug!(" > resulting class invalidations: {:?}", self.classes); + debug!(" > resulting id invalidations: {:?}", self.ids); + debug!( + " > resulting local name invalidations: {:?}", + self.local_names + ); + debug!(" > fully_invalid: {}", self.fully_invalid); + } + + /// Clears the invalidation set, invalidating elements as needed if + /// `document_element` is provided. + /// + /// Returns true if any invalidations ocurred. + pub fn flush<E>(&mut self, document_element: Option<E>, snapshots: Option<&SnapshotMap>) -> bool + where + E: TElement, + { + debug!( + "Stylist::flush({:?}, snapshots: {})", + document_element, + snapshots.is_some() + ); + let have_invalidations = match document_element { + Some(e) => self.process_invalidations(e, snapshots), + None => false, + }; + self.clear(); + have_invalidations + } + + /// Returns whether there's no invalidation to process. + pub fn is_empty(&self) -> bool { + !self.fully_invalid && + self.classes.is_empty() && + self.ids.is_empty() && + self.local_names.is_empty() + } + + fn invalidation_kind_for<E>( + &self, + element: E, + snapshot: Option<&Snapshot>, + quirks_mode: QuirksMode, + ) -> InvalidationKind + where + E: TElement, + { + debug_assert!(!self.fully_invalid); + + let mut kind = InvalidationKind::None; + + if !self.classes.is_empty() { + element.each_class(|c| { + kind.add(self.classes.get(c, quirks_mode)); + }); + + if kind.is_scope() { + return kind; + } + + if let Some(snapshot) = snapshot { + snapshot.each_class(|c| { + kind.add(self.classes.get(c, quirks_mode)); + }); + + if kind.is_scope() { + return kind; + } + } + } + + if !self.ids.is_empty() { + if let Some(ref id) = element.id() { + kind.add(self.ids.get(id, quirks_mode)); + if kind.is_scope() { + return kind; + } + } + + if let Some(ref old_id) = snapshot.and_then(|s| s.id_attr()) { + kind.add(self.ids.get(old_id, quirks_mode)); + if kind.is_scope() { + return kind; + } + } + } + + if !self.local_names.is_empty() { + kind.add(self.local_names.get(element.local_name())); + } + + kind + } + + /// Clears the invalidation set without processing. + pub fn clear(&mut self) { + self.classes.clear(); + self.ids.clear(); + self.local_names.clear(); + self.fully_invalid = false; + debug_assert!(self.is_empty()); + } + + fn process_invalidations<E>(&self, element: E, snapshots: Option<&SnapshotMap>) -> bool + where + E: TElement, + { + debug!("Stylist::process_invalidations({:?}, {:?})", element, self); + + { + let mut data = match element.mutate_data() { + Some(data) => data, + None => return false, + }; + + if self.fully_invalid { + debug!("process_invalidations: fully_invalid({:?})", element); + data.hint.insert(RestyleHint::restyle_subtree()); + return true; + } + } + + if self.is_empty() { + debug!("process_invalidations: empty invalidation set"); + return false; + } + + let quirks_mode = element.as_node().owner_doc().quirks_mode(); + self.process_invalidations_in_subtree(element, snapshots, quirks_mode) + } + + /// Process style invalidations in a given subtree. This traverses the + /// subtree looking for elements that match the invalidations in our hash + /// map members. + /// + /// Returns whether it invalidated at least one element's style. + #[allow(unsafe_code)] + fn process_invalidations_in_subtree<E>( + &self, + element: E, + snapshots: Option<&SnapshotMap>, + quirks_mode: QuirksMode, + ) -> bool + where + E: TElement, + { + debug!("process_invalidations_in_subtree({:?})", element); + let mut data = match element.mutate_data() { + Some(data) => data, + None => return false, + }; + + if !data.has_styles() { + return false; + } + + if data.hint.contains_subtree() { + debug!( + "process_invalidations_in_subtree: {:?} was already invalid", + element + ); + return false; + } + + let element_wrapper = snapshots.map(|s| ElementWrapper::new(element, s)); + let snapshot = element_wrapper.as_ref().and_then(|e| e.snapshot()); + + match self.invalidation_kind_for(element, snapshot, quirks_mode) { + InvalidationKind::None => {}, + InvalidationKind::Element => { + debug!( + "process_invalidations_in_subtree: {:?} matched self", + element + ); + data.hint.insert(RestyleHint::RESTYLE_SELF); + }, + InvalidationKind::Scope => { + debug!( + "process_invalidations_in_subtree: {:?} matched subtree", + element + ); + data.hint.insert(RestyleHint::restyle_subtree()); + return true; + }, + } + + let mut any_children_invalid = false; + + for child in element.traversal_children() { + let child = match child.as_element() { + Some(e) => e, + None => continue, + }; + + any_children_invalid |= + self.process_invalidations_in_subtree(child, snapshots, quirks_mode); + } + + if any_children_invalid { + debug!( + "Children of {:?} changed, setting dirty descendants", + element + ); + unsafe { element.set_dirty_descendants() } + } + + data.hint.contains(RestyleHint::RESTYLE_SELF) || any_children_invalid + } + + /// TODO(emilio): Reuse the bucket stuff from selectormap? That handles + /// :is() / :where() etc. + fn scan_component( + component: &Component<SelectorImpl>, + invalidation: &mut Option<Invalidation>, + ) { + match *component { + Component::LocalName(LocalName { + ref name, + ref lower_name, + }) => { + if invalidation.is_none() { + *invalidation = Some(Invalidation::LocalName { + name: name.clone(), + lower_name: lower_name.clone(), + }); + } + }, + Component::Class(ref class) => { + if invalidation.as_ref().map_or(true, |s| !s.is_id_or_class()) { + *invalidation = Some(Invalidation::Class(class.clone())); + } + }, + Component::ID(ref id) => { + if invalidation.as_ref().map_or(true, |s| !s.is_id()) { + *invalidation = Some(Invalidation::ID(id.clone())); + } + }, + _ => { + // Ignore everything else, at least for now. + }, + } + } + + /// Collect invalidations for a given selector. + /// + /// We look at the outermost local name, class, or ID selector to the left + /// of an ancestor combinator, in order to restyle only a given subtree. + /// + /// If the selector has no ancestor combinator, then we do the same for + /// the only sequence it has, but record it as an element invalidation + /// instead of a subtree invalidation. + /// + /// We prefer IDs to classs, and classes to local names, on the basis + /// that the former should be more specific than the latter. We also + /// prefer to generate subtree invalidations for the outermost part + /// of the selector, to reduce the amount of traversal we need to do + /// when flushing invalidations. + fn collect_invalidations( + &mut self, + selector: &Selector<SelectorImpl>, + quirks_mode: QuirksMode, + ) { + debug!( + "StylesheetInvalidationSet::collect_invalidations({:?})", + selector + ); + + let mut element_invalidation: Option<Invalidation> = None; + let mut subtree_invalidation: Option<Invalidation> = None; + + let mut scan_for_element_invalidation = true; + let mut scan_for_subtree_invalidation = false; + + let mut iter = selector.iter(); + + loop { + for component in &mut iter { + if scan_for_element_invalidation { + Self::scan_component(component, &mut element_invalidation); + } else if scan_for_subtree_invalidation { + Self::scan_component(component, &mut subtree_invalidation); + } + } + match iter.next_sequence() { + None => break, + Some(combinator) => { + scan_for_subtree_invalidation = combinator.is_ancestor(); + }, + } + scan_for_element_invalidation = false; + } + + if let Some(s) = subtree_invalidation { + debug!(" > Found subtree invalidation: {:?}", s); + if self.insert_invalidation(s, InvalidationKind::Scope, quirks_mode) { + return; + } + } + + if let Some(s) = element_invalidation { + debug!(" > Found element invalidation: {:?}", s); + if self.insert_invalidation(s, InvalidationKind::Element, quirks_mode) { + return; + } + } + + // The selector was of a form that we can't handle. Any element could + // match it, so let's just bail out. + debug!(" > Can't handle selector or OOMd, marking fully invalid"); + self.invalidate_fully() + } + + fn insert_invalidation( + &mut self, + invalidation: Invalidation, + kind: InvalidationKind, + quirks_mode: QuirksMode, + ) -> bool { + match invalidation { + Invalidation::Class(c) => { + let entry = match self.classes.try_entry(c.0, quirks_mode) { + Ok(e) => e, + Err(..) => return false, + }; + *entry.or_insert(InvalidationKind::None) |= kind; + }, + Invalidation::ID(i) => { + let entry = match self.ids.try_entry(i.0, quirks_mode) { + Ok(e) => e, + Err(..) => return false, + }; + *entry.or_insert(InvalidationKind::None) |= kind; + }, + Invalidation::LocalName { name, lower_name } => { + let insert_lower = name != lower_name; + if self.local_names.try_reserve(1).is_err() { + return false; + } + let entry = self.local_names.entry(name); + *entry.or_insert(InvalidationKind::None) |= kind; + if insert_lower { + if self.local_names.try_reserve(1).is_err() { + return false; + } + let entry = self.local_names.entry(lower_name); + *entry.or_insert(InvalidationKind::None) |= kind; + } + }, + } + + true + } + + /// Collects invalidations for a given CSS rule, if not fully invalid + /// already. + /// + /// TODO(emilio): we can't check whether the rule is inside a non-effective + /// subtree, we potentially could do that. + pub fn rule_changed<S>( + &mut self, + stylesheet: &S, + rule: &CssRule, + guard: &SharedRwLockReadGuard, + device: &Device, + quirks_mode: QuirksMode, + change_kind: RuleChangeKind, + ) where + S: StylesheetInDocument, + { + debug!("StylesheetInvalidationSet::rule_changed"); + if self.fully_invalid { + return; + } + + if !stylesheet.enabled() || !stylesheet.is_effective_for_device(device, guard) { + debug!(" > Stylesheet was not effective"); + return; // Nothing to do here. + } + + // If the change is generic, we don't have the old rule information to know e.g., the old + // media condition, or the old selector text, so we might need to invalidate more + // aggressively. That only applies to the changed rules, for other rules we can just + // collect invalidations as normal. + let is_generic_change = change_kind == RuleChangeKind::Generic; + self.collect_invalidations_for_rule(rule, guard, device, quirks_mode, is_generic_change); + if self.fully_invalid { + return; + } + + if !is_generic_change && !EffectiveRules::is_effective(guard, device, quirks_mode, rule) { + return; + } + + let rules = EffectiveRulesIterator::effective_children(device, quirks_mode, guard, rule); + for rule in rules { + self.collect_invalidations_for_rule( + rule, + guard, + device, + quirks_mode, + /* is_generic_change = */ false, + ); + if self.fully_invalid { + break; + } + } + } + + /// Collects invalidations for a given CSS rule. + fn collect_invalidations_for_rule( + &mut self, + rule: &CssRule, + guard: &SharedRwLockReadGuard, + device: &Device, + quirks_mode: QuirksMode, + is_generic_change: bool, + ) { + use crate::stylesheets::CssRule::*; + debug!("StylesheetInvalidationSet::collect_invalidations_for_rule"); + debug_assert!(!self.fully_invalid, "Not worth being here!"); + + match *rule { + Style(ref lock) => { + if is_generic_change { + // TODO(emilio): We need to do this for selector / keyframe + // name / font-face changes, because we don't have the old + // selector / name. If we distinguish those changes + // specially, then we can at least use this invalidation for + // style declaration changes. + return self.invalidate_fully(); + } + + let style_rule = lock.read_with(guard); + for selector in style_rule.selectors.slice() { + self.collect_invalidations(selector, quirks_mode); + if self.fully_invalid { + return; + } + } + }, + Namespace(..) => { + // It's not clear what handling changes for this correctly would + // look like. + }, + LayerStatement(..) => { + // Layer statement insertions might alter styling order, so we need to always + // invalidate fully. + return self.invalidate_fully(); + }, + Document(..) | Import(..) | Media(..) | Supports(..) | Container(..) | + LayerBlock(..) => { + // Do nothing, relevant nested rules are visited as part of rule iteration. + }, + FontFace(..) => { + // Do nothing, @font-face doesn't affect computed style information on it's own. + // We'll restyle when the font face loads, if needed. + }, + Page(..) | Margin(..) => { + // Do nothing, we don't support OM mutations on print documents, and page rules + // can't affect anything else. + }, + Keyframes(ref lock) => { + if is_generic_change { + return self.invalidate_fully(); + } + let keyframes_rule = lock.read_with(guard); + if device.animation_name_may_be_referenced(&keyframes_rule.name) { + debug!( + " > Found @keyframes rule potentially referenced \ + from the page, marking the whole tree invalid." + ); + self.invalidate_fully(); + } else { + // Do nothing, this animation can't affect the style of existing elements. + } + }, + CounterStyle(..) | Property(..) | FontFeatureValues(..) | FontPaletteValues(..) => { + debug!(" > Found unsupported rule, marking the whole subtree invalid."); + self.invalidate_fully(); + }, + } + } +} |