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style: Refactor the traversal so it's more easy to read and straight-forward.

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Emilio Cobos Álvarez 2017-02-01 14:28:47 +01:00
parent 8859aa004f
commit 2594cb9c33
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5 changed files with 162 additions and 113 deletions
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126
components/style/traversal.rs
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@ -8,7 +8,7 @@
use atomic_refcell::{AtomicRefCell, AtomicRefMut};
use context::{SharedStyleContext, StyleContext, ThreadLocalStyleContext};
use data::{ElementData, ElementStyles, StoredRestyleHint};
use data::{ElementData, ElementStyles, RestyleKind, StoredRestyleHint};
use dom::{NodeInfo, TElement, TNode};
use matching::{MatchMethods, StyleSharingResult};
use restyle_hints::{RESTYLE_DESCENDANTS, RESTYLE_SELF};
@ -453,9 +453,6 @@ pub fn recalc_style_at<E, D>(traversal: &D,
// Computes style, returning true if the inherited styles changed for this
// element.
//
// FIXME(bholley): This should differentiate between matching and cascading,
// since we have separate bits for each now.
fn compute_style<E, D>(_traversal: &D,
traversal_data: &mut PerLevelTraversalData,
context: &mut StyleContext<E>,
@ -467,73 +464,74 @@ fn compute_style<E, D>(_traversal: &D,
context.thread_local.statistics.elements_styled += 1;
let shared_context = context.shared;
// Ensure the bloom filter is up to date.
//
// TODO(emilio): In theory we could avoid a bit of this work in the style
// attribute case.
let dom_depth = context.thread_local.bloom_filter
.insert_parents_recovering(element, traversal_data.current_dom_depth);
// TODO(emilio): Make cascade_input less expensive to compute in the cases
// we don't need to run selector matching.
let cascade_input = match data.restyle_kind() {
RestyleKind::MatchAndCascade => {
// Check to see whether we can share a style with someone.
let sharing_result = unsafe {
element.share_style_if_possible(&mut context.thread_local.style_sharing_candidate_cache,
shared_context,
&mut data)
};
// Update the dom depth with the up-to-date dom depth.
//
// Note that this is always the same than the pre-existing depth, but it can
// change from unknown to known at this step.
traversal_data.current_dom_depth = Some(dom_depth);
context.thread_local.bloom_filter.assert_complete(element);
// Check to see whether we can share a style with someone.
let sharing_result = if element.parent_element().is_none() {
StyleSharingResult::CannotShare
} else {
unsafe { element.share_style_if_possible(&mut context.thread_local.style_sharing_candidate_cache,
shared_context, &mut data) }
};
// Otherwise, match and cascade selectors.
match sharing_result {
StyleSharingResult::CannotShare => {
let match_results;
let shareable_element = {
// Perform the CSS selector matching.
context.thread_local.statistics.elements_matched += 1;
// TODO(emilio): Here we'll need to support animation-only hints
// and similar.
match_results = if data.needs_only_style_attribute_update() {
element.update_style_attribute(context, data)
} else {
let filter = context.thread_local.bloom_filter.filter();
element.match_element(context, Some(filter))
};
if match_results.primary_is_shareable() {
Some(element)
} else {
match sharing_result {
StyleSharingResult::StyleWasShared(index) => {
context.thread_local.statistics.styles_shared += 1;
context.thread_local.style_sharing_candidate_cache.touch(index);
None
}
};
let relations = match_results.relations;
StyleSharingResult::CannotShare => {
// Ensure the bloom filter is up to date.
let dom_depth =
context.thread_local.bloom_filter
.insert_parents_recovering(element,
traversal_data.current_dom_depth);
// Perform the CSS cascade.
unsafe {
let shareable = match_results.primary_is_shareable();
element.cascade_node(context, &mut data,
element.parent_element(),
match_results.primary,
match_results.per_pseudo,
shareable);
}
// Update the dom depth with the up-to-date dom depth.
//
// Note that this is always the same than the pre-existing depth,
// but it can change from unknown to known at this step.
traversal_data.current_dom_depth = Some(dom_depth);
// Add ourselves to the LRU cache.
if let Some(element) = shareable_element {
context.thread_local
.style_sharing_candidate_cache
.insert_if_possible(&element, &data.styles().primary.values, relations);
context.thread_local.bloom_filter.assert_complete(element);
// Perform the CSS selector matching.
context.thread_local.statistics.elements_matched += 1;
let filter = context.thread_local.bloom_filter.filter();
Some(element.match_element(context, Some(filter)))
}
}
}
StyleSharingResult::StyleWasShared(index) => {
context.thread_local.statistics.styles_shared += 1;
context.thread_local.style_sharing_candidate_cache.touch(index);
RestyleKind::CascadeWithReplacements(hint) => {
Some(element.cascade_with_replacements(hint, context, &mut data))
}
RestyleKind::CascadeOnly => {
// TODO(emilio): Stop doing this work, and teach cascade_node about
// the current style instead.
Some(element.match_results_from_current_style(&*data))
}
};
if let Some(match_results) = cascade_input {
// Perform the CSS cascade.
let shareable = match_results.primary_is_shareable();
unsafe {
element.cascade_node(context, &mut data,
element.parent_element(),
match_results.primary,
match_results.per_pseudo,
shareable);
}
if shareable {
// Add ourselves to the LRU cache.
context.thread_local
.style_sharing_candidate_cache
.insert_if_possible(&element,
&data.styles().primary.values,
match_results.relations);
}
}