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Diffstat (limited to 'servo/components/style/style_resolver.rs')
| -rw-r--r-- | servo/components/style/style_resolver.rs | 589 |
1 files changed, 589 insertions, 0 deletions
diff --git a/servo/components/style/style_resolver.rs b/servo/components/style/style_resolver.rs new file mode 100644 index 0000000000..a082b2cbff --- /dev/null +++ b/servo/components/style/style_resolver.rs @@ -0,0 +1,589 @@ +/* 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/. */ + +//! Style resolution for a given element or pseudo-element. + +use crate::applicable_declarations::ApplicableDeclarationList; +use crate::computed_value_flags::ComputedValueFlags; +use crate::context::{CascadeInputs, ElementCascadeInputs, StyleContext}; +use crate::data::{EagerPseudoStyles, ElementStyles}; +use crate::dom::TElement; +use crate::matching::MatchMethods; +use crate::properties::longhands::display::computed_value::T as Display; +use crate::properties::ComputedValues; +use crate::rule_tree::StrongRuleNode; +use crate::selector_parser::{PseudoElement, SelectorImpl}; +use crate::stylist::RuleInclusion; +use log::Level::Trace; +use selectors::matching::{MatchingContext, NeedsSelectorFlags}; +use selectors::matching::{MatchingMode, VisitedHandlingMode}; +use servo_arc::Arc; + +/// Whether pseudo-elements should be resolved or not. +#[derive(Clone, Copy, Debug, Eq, PartialEq)] +pub enum PseudoElementResolution { + /// Only resolve pseudo-styles if possibly applicable. + IfApplicable, + /// Force pseudo-element resolution. + Force, +} + +/// A struct that takes care of resolving the style of a given element. +pub struct StyleResolverForElement<'a, 'ctx, 'le, E> +where + 'ctx: 'a, + 'le: 'ctx, + E: TElement + MatchMethods + 'le, +{ + element: E, + context: &'a mut StyleContext<'ctx, E>, + rule_inclusion: RuleInclusion, + pseudo_resolution: PseudoElementResolution, + _marker: ::std::marker::PhantomData<&'le E>, +} + +struct MatchingResults { + rule_node: StrongRuleNode, + flags: ComputedValueFlags, +} + +/// A style returned from the resolver machinery. +pub struct ResolvedStyle(pub Arc<ComputedValues>); + +/// The primary style of an element or an element-backed pseudo-element. +pub struct PrimaryStyle { + /// The style itself. + pub style: ResolvedStyle, + /// Whether the style was reused from another element via the rule node (see + /// `StyleSharingCache::lookup_by_rules`). + pub reused_via_rule_node: bool, +} + +/// A set of style returned from the resolver machinery. +pub struct ResolvedElementStyles { + /// Primary style. + pub primary: PrimaryStyle, + /// Pseudo styles. + pub pseudos: EagerPseudoStyles, +} + +impl ResolvedElementStyles { + /// Convenience accessor for the primary style. + pub fn primary_style(&self) -> &Arc<ComputedValues> { + &self.primary.style.0 + } + + /// Convenience mutable accessor for the style. + pub fn primary_style_mut(&mut self) -> &mut Arc<ComputedValues> { + &mut self.primary.style.0 + } +} + +impl PrimaryStyle { + /// Convenience accessor for the style. + pub fn style(&self) -> &ComputedValues { + &*self.style.0 + } +} + +impl From<ResolvedElementStyles> for ElementStyles { + fn from(r: ResolvedElementStyles) -> ElementStyles { + ElementStyles { + primary: Some(r.primary.style.0), + pseudos: r.pseudos, + } + } +} + +fn with_default_parent_styles<E, F, R>(element: E, f: F) -> R +where + E: TElement, + F: FnOnce(Option<&ComputedValues>, Option<&ComputedValues>) -> R, +{ + let parent_el = element.inheritance_parent(); + let parent_data = parent_el.as_ref().and_then(|e| e.borrow_data()); + let parent_style = parent_data.as_ref().map(|d| d.styles.primary()); + + let mut layout_parent_el = parent_el.clone(); + let layout_parent_data; + let mut layout_parent_style = parent_style; + if parent_style.map_or(false, |s| s.is_display_contents()) { + layout_parent_el = Some(layout_parent_el.unwrap().layout_parent()); + layout_parent_data = layout_parent_el.as_ref().unwrap().borrow_data().unwrap(); + layout_parent_style = Some(layout_parent_data.styles.primary()); + } + + f( + parent_style.map(|x| &**x), + layout_parent_style.map(|s| &**s), + ) +} + +fn layout_parent_style_for_pseudo<'a>( + primary_style: &'a PrimaryStyle, + layout_parent_style: Option<&'a ComputedValues>, +) -> Option<&'a ComputedValues> { + if primary_style.style().is_display_contents() { + layout_parent_style + } else { + Some(primary_style.style()) + } +} + +fn eager_pseudo_is_definitely_not_generated( + pseudo: &PseudoElement, + style: &ComputedValues, +) -> bool { + if !pseudo.is_before_or_after() { + return false; + } + + if !style + .flags + .intersects(ComputedValueFlags::DISPLAY_DEPENDS_ON_INHERITED_STYLE) && + style.get_box().clone_display() == Display::None + { + return true; + } + + if !style + .flags + .intersects(ComputedValueFlags::CONTENT_DEPENDS_ON_INHERITED_STYLE) && + style.ineffective_content_property() + { + return true; + } + + false +} + +impl<'a, 'ctx, 'le, E> StyleResolverForElement<'a, 'ctx, 'le, E> +where + 'ctx: 'a, + 'le: 'ctx, + E: TElement + MatchMethods + 'le, +{ + /// Trivially construct a new StyleResolverForElement. + pub fn new( + element: E, + context: &'a mut StyleContext<'ctx, E>, + rule_inclusion: RuleInclusion, + pseudo_resolution: PseudoElementResolution, + ) -> Self { + Self { + element, + context, + rule_inclusion, + pseudo_resolution, + _marker: ::std::marker::PhantomData, + } + } + + /// Resolve just the style of a given element. + pub fn resolve_primary_style( + &mut self, + parent_style: Option<&ComputedValues>, + layout_parent_style: Option<&ComputedValues>, + ) -> PrimaryStyle { + let primary_results = self.match_primary(VisitedHandlingMode::AllLinksUnvisited); + + let inside_link = parent_style.map_or(false, |s| s.visited_style().is_some()); + + let visited_rules = if self.context.shared.visited_styles_enabled && + (inside_link || self.element.is_link()) + { + let visited_matching_results = + self.match_primary(VisitedHandlingMode::RelevantLinkVisited); + Some(visited_matching_results.rule_node) + } else { + None + }; + + self.cascade_primary_style( + CascadeInputs { + rules: Some(primary_results.rule_node), + visited_rules, + flags: primary_results.flags, + }, + parent_style, + layout_parent_style, + ) + } + + fn cascade_primary_style( + &mut self, + inputs: CascadeInputs, + parent_style: Option<&ComputedValues>, + layout_parent_style: Option<&ComputedValues>, + ) -> PrimaryStyle { + // Before doing the cascade, check the sharing cache and see if we can + // reuse the style via rule node identity. + let may_reuse = self.element.matches_user_and_content_rules() && + parent_style.is_some() && + inputs.rules.is_some(); + + if may_reuse { + let cached = self.context.thread_local.sharing_cache.lookup_by_rules( + self.context.shared, + parent_style.unwrap(), + inputs.rules.as_ref().unwrap(), + inputs.visited_rules.as_ref(), + self.element, + ); + if let Some(mut primary_style) = cached { + self.context.thread_local.statistics.styles_reused += 1; + primary_style.reused_via_rule_node |= true; + return primary_style; + } + } + + // No style to reuse. Cascade the style, starting with visited style + // if necessary. + PrimaryStyle { + style: self.cascade_style_and_visited( + inputs, + parent_style, + layout_parent_style, + /* pseudo = */ None, + ), + reused_via_rule_node: false, + } + } + + /// Resolve the style of a given element, and all its eager pseudo-elements. + pub fn resolve_style( + &mut self, + parent_style: Option<&ComputedValues>, + layout_parent_style: Option<&ComputedValues>, + ) -> ResolvedElementStyles { + let primary_style = self.resolve_primary_style(parent_style, layout_parent_style); + + let mut pseudo_styles = EagerPseudoStyles::default(); + + if !self.element.is_pseudo_element() { + let layout_parent_style_for_pseudo = + layout_parent_style_for_pseudo(&primary_style, layout_parent_style); + SelectorImpl::each_eagerly_cascaded_pseudo_element(|pseudo| { + let pseudo_style = self.resolve_pseudo_style( + &pseudo, + &primary_style, + layout_parent_style_for_pseudo, + ); + + if let Some(style) = pseudo_style { + if !matches!(self.pseudo_resolution, PseudoElementResolution::Force) && + eager_pseudo_is_definitely_not_generated(&pseudo, &style.0) + { + return; + } + pseudo_styles.set(&pseudo, style.0); + } + }) + } + + ResolvedElementStyles { + primary: primary_style, + pseudos: pseudo_styles, + } + } + + /// Resolve an element's styles with the default inheritance parent/layout + /// parents. + pub fn resolve_style_with_default_parents(&mut self) -> ResolvedElementStyles { + with_default_parent_styles(self.element, |parent_style, layout_parent_style| { + self.resolve_style(parent_style, layout_parent_style) + }) + } + + /// Cascade a set of rules, using the default parent for inheritance. + pub fn cascade_style_and_visited_with_default_parents( + &mut self, + inputs: CascadeInputs, + ) -> ResolvedStyle { + with_default_parent_styles(self.element, |parent_style, layout_parent_style| { + self.cascade_style_and_visited( + inputs, + parent_style, + layout_parent_style, + /* pseudo = */ None, + ) + }) + } + + /// Cascade a set of rules for pseudo element, using the default parent for inheritance. + pub fn cascade_style_and_visited_for_pseudo_with_default_parents( + &mut self, + inputs: CascadeInputs, + pseudo: &PseudoElement, + primary_style: &PrimaryStyle, + ) -> ResolvedStyle { + with_default_parent_styles(self.element, |_, layout_parent_style| { + let layout_parent_style_for_pseudo = + layout_parent_style_for_pseudo(primary_style, layout_parent_style); + + self.cascade_style_and_visited( + inputs, + Some(primary_style.style()), + layout_parent_style_for_pseudo, + Some(pseudo), + ) + }) + } + + fn cascade_style_and_visited( + &mut self, + inputs: CascadeInputs, + parent_style: Option<&ComputedValues>, + layout_parent_style: Option<&ComputedValues>, + pseudo: Option<&PseudoElement>, + ) -> ResolvedStyle { + debug_assert!(pseudo.map_or(true, |p| p.is_eager())); + + let implemented_pseudo = self.element.implemented_pseudo_element(); + let pseudo = pseudo.or(implemented_pseudo.as_ref()); + + let mut conditions = Default::default(); + let values = self.context.shared.stylist.cascade_style_and_visited( + Some(self.element), + pseudo, + inputs, + &self.context.shared.guards, + pseudo.and(parent_style), + parent_style, + parent_style, + layout_parent_style, + Some(&self.context.thread_local.rule_cache), + &mut conditions, + ); + + self.context.thread_local.rule_cache.insert_if_possible( + &self.context.shared.guards, + &values, + pseudo, + &conditions, + ); + + ResolvedStyle(values) + } + + /// Cascade the element and pseudo-element styles with the default parents. + pub fn cascade_styles_with_default_parents( + &mut self, + inputs: ElementCascadeInputs, + ) -> ResolvedElementStyles { + with_default_parent_styles(self.element, move |parent_style, layout_parent_style| { + let primary_style = + self.cascade_primary_style(inputs.primary, parent_style, layout_parent_style); + + let mut pseudo_styles = EagerPseudoStyles::default(); + if let Some(mut pseudo_array) = inputs.pseudos.into_array() { + let layout_parent_style_for_pseudo = if primary_style.style().is_display_contents() + { + layout_parent_style + } else { + Some(primary_style.style()) + }; + + for (i, inputs) in pseudo_array.iter_mut().enumerate() { + if let Some(inputs) = inputs.take() { + let pseudo = PseudoElement::from_eager_index(i); + + let style = self.cascade_style_and_visited( + inputs, + Some(primary_style.style()), + layout_parent_style_for_pseudo, + Some(&pseudo), + ); + + if !matches!(self.pseudo_resolution, PseudoElementResolution::Force) && + eager_pseudo_is_definitely_not_generated(&pseudo, &style.0) + { + continue; + } + + pseudo_styles.set(&pseudo, style.0); + } + } + } + + ResolvedElementStyles { + primary: primary_style, + pseudos: pseudo_styles, + } + }) + } + + fn resolve_pseudo_style( + &mut self, + pseudo: &PseudoElement, + originating_element_style: &PrimaryStyle, + layout_parent_style: Option<&ComputedValues>, + ) -> Option<ResolvedStyle> { + let MatchingResults { + rule_node, + mut flags, + } = self.match_pseudo( + &originating_element_style.style.0, + pseudo, + VisitedHandlingMode::AllLinksUnvisited, + )?; + + let mut visited_rules = None; + if originating_element_style.style().visited_style().is_some() { + visited_rules = self + .match_pseudo( + &originating_element_style.style.0, + pseudo, + VisitedHandlingMode::RelevantLinkVisited, + ) + .map(|results| { + flags |= results.flags; + results.rule_node + }); + } + + Some(self.cascade_style_and_visited( + CascadeInputs { + rules: Some(rule_node), + visited_rules, + flags, + }, + Some(originating_element_style.style()), + layout_parent_style, + Some(pseudo), + )) + } + + fn match_primary(&mut self, visited_handling: VisitedHandlingMode) -> MatchingResults { + debug!( + "Match primary for {:?}, visited: {:?}", + self.element, visited_handling + ); + let mut applicable_declarations = ApplicableDeclarationList::new(); + + let bloom_filter = self.context.thread_local.bloom_filter.filter(); + let nth_index_cache = &mut self.context.thread_local.nth_index_cache; + let mut matching_context = MatchingContext::new_for_visited( + MatchingMode::Normal, + Some(bloom_filter), + nth_index_cache, + visited_handling, + self.context.shared.quirks_mode(), + NeedsSelectorFlags::Yes, + ); + + let stylist = &self.context.shared.stylist; + let implemented_pseudo = self.element.implemented_pseudo_element(); + // Compute the primary rule node. + stylist.push_applicable_declarations( + self.element, + implemented_pseudo.as_ref(), + self.element.style_attribute(), + self.element.smil_override(), + self.element.animation_declarations(self.context.shared), + self.rule_inclusion, + &mut applicable_declarations, + &mut matching_context, + ); + + // FIXME(emilio): This is a hack for animations, and should go away. + self.element.unset_dirty_style_attribute(); + + let rule_node = stylist + .rule_tree() + .compute_rule_node(&mut applicable_declarations, &self.context.shared.guards); + + if log_enabled!(Trace) { + trace!("Matched rules for {:?}:", self.element); + for rn in rule_node.self_and_ancestors() { + let source = rn.style_source(); + if source.is_some() { + trace!(" > {:?}", source); + } + } + } + + if matching_context.considered_relative_selector { + // This is a bit awkward - ideally, the flag is set directly where `considered_relative_selector` + // is; however, in that context, the implementation detail of `extra_data` is not visible, so + // it's done here. A trait for manipulating the flags is an option, but not worth it for a single flag. + matching_context + .extra_data + .cascade_input_flags + .insert(ComputedValueFlags::CONSIDERED_RELATIVE_SELECTOR); + } + + MatchingResults { + rule_node, + flags: matching_context.extra_data.cascade_input_flags, + } + } + + fn match_pseudo( + &mut self, + originating_element_style: &ComputedValues, + pseudo_element: &PseudoElement, + visited_handling: VisitedHandlingMode, + ) -> Option<MatchingResults> { + debug!( + "Match pseudo {:?} for {:?}, visited: {:?}", + self.element, pseudo_element, visited_handling + ); + debug_assert!(pseudo_element.is_eager()); + debug_assert!( + !self.element.is_pseudo_element(), + "Element pseudos can't have any other eager pseudo." + ); + + let mut applicable_declarations = ApplicableDeclarationList::new(); + + let stylist = &self.context.shared.stylist; + + if !self + .element + .may_generate_pseudo(pseudo_element, originating_element_style) + { + return None; + } + + let bloom_filter = self.context.thread_local.bloom_filter.filter(); + let nth_index_cache = &mut self.context.thread_local.nth_index_cache; + + let mut matching_context = MatchingContext::<'_, E::Impl>::new_for_visited( + MatchingMode::ForStatelessPseudoElement, + Some(bloom_filter), + nth_index_cache, + visited_handling, + self.context.shared.quirks_mode(), + NeedsSelectorFlags::Yes, + ); + matching_context.extra_data.originating_element_style = Some(originating_element_style); + + // NB: We handle animation rules for ::before and ::after when + // traversing them. + stylist.push_applicable_declarations( + self.element, + Some(pseudo_element), + None, + None, + /* animation_declarations = */ Default::default(), + self.rule_inclusion, + &mut applicable_declarations, + &mut matching_context, + ); + + if applicable_declarations.is_empty() { + return None; + } + + let rule_node = stylist + .rule_tree() + .compute_rule_node(&mut applicable_declarations, &self.context.shared.guards); + + Some(MatchingResults { + rule_node, + flags: matching_context.extra_data.cascade_input_flags, + }) + } +} |