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Add a helper method for getting our style parent and its ComputedValu…

…es while matching.

Part 3 of the fix for Gecko bug 1364242: https://bugzilla.mozilla.org/show_bug.cgi?id=1364242
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bzbarsky committed Jun 30, 2017
1 parent 52d1b59 commit 759038e6875da9c1bcd03d94fb8486073c707785
Showing with 37 additions and 15 deletions.
  1. +37 −15 components/style/matching.rs
@@ -288,6 +288,28 @@ trait PrivateMatchMethods: TElement {
}
}

/// Get the ComputedValues (if any) for our inheritance parent.
fn get_inherited_style_and_parent(&self) -> ParentElementAndStyle<Self> {
let parent_el = self.inheritance_parent();
let parent_data = parent_el.as_ref().and_then(|e| e.borrow_data());
let parent_style = parent_data.as_ref().map(|d| {
// Sometimes Gecko eagerly styles things without processing
// pending restyles first. In general we'd like to avoid this,
// but there can be good reasons (for example, needing to
// construct a frame for some small piece of newly-added
// content in order to do something specific with that frame,
// but not wanting to flush all of layout).
debug_assert!(cfg!(feature = "gecko") ||
parent_el.unwrap().has_current_styles(d));
d.styles.primary()
});

ParentElementAndStyle {
element: parent_el,
style: parent_style.cloned(),
}
}

/// A common path for the cascade used by both primary elements and eager
/// pseudo-elements after collecting the appropriate rules to use.
///
@@ -318,23 +340,12 @@ trait PrivateMatchMethods: TElement {

// Grab the inherited values.
let parent_el;
let parent_data;
let element_and_style; // So parent_el and style_to_inherit_from are known live.
let style_to_inherit_from = match cascade_target {
CascadeTarget::Normal => {
parent_el = self.inheritance_parent();
parent_data = parent_el.as_ref().and_then(|e| e.borrow_data());
let parent_style = parent_data.as_ref().map(|d| {
// Sometimes Gecko eagerly styles things without processing
// pending restyles first. In general we'd like to avoid this,
// but there can be good reasons (for example, needing to
// construct a frame for some small piece of newly-added
// content in order to do something specific with that frame,
// but not wanting to flush all of layout).
debug_assert!(cfg!(feature = "gecko") ||
parent_el.unwrap().has_current_styles(d));
d.styles.primary()
});
parent_style.map(|s| cascade_visited.values(s))
element_and_style = self.get_inherited_style_and_parent();
parent_el = element_and_style.element;
element_and_style.style.as_ref().map(|s| cascade_visited.values(s))
}
CascadeTarget::EagerPseudo => {
parent_el = Some(self.clone());
@@ -877,6 +888,17 @@ trait PrivateMatchMethods: TElement {

impl<E: TElement> PrivateMatchMethods for E {}

/// A struct that holds an element we inherit from and its ComputedValues.
#[derive(Debug)]
struct ParentElementAndStyle<E: TElement> {
/// Our style parent element.
element: Option<E>,
/// Element's primary ComputedValues. Not a borrow because we can't prove
/// that the thing hanging off element won't change while we're passing this
/// struct around.
style: Option<Arc<ComputedValues>>,
}

/// Collects the outputs of the primary matching process, including the rule
/// node and other associated data.
#[derive(Debug)]

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