Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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,
+        })
+    }
+}