style: Record names that appear in attribute selectors.

This commit is contained in:
Cameron McCormack 2017-05-08 16:06:15 +08:00
parent 48fdda3f07
commit 5cf915118e
2 changed files with 74 additions and 1 deletions

View file

@ -27,7 +27,7 @@ use selectors::Element;
use selectors::bloom::BloomFilter;
use selectors::matching::{AFFECTED_BY_STYLE_ATTRIBUTE, AFFECTED_BY_PRESENTATIONAL_HINTS};
use selectors::matching::{ElementSelectorFlags, StyleRelations, matches_selector};
use selectors::parser::{Combinator, Component, Selector, SelectorInner, SelectorIter};
use selectors::parser::{AttrSelector, Combinator, Component, Selector, SelectorInner, SelectorIter};
use selectors::parser::{SelectorMethods, LocalName as LocalNameSelector};
use selectors::visitor::SelectorVisitor;
use shared_lock::{Locked, SharedRwLockReadGuard, StylesheetGuards};
@ -118,6 +118,23 @@ pub struct Stylist {
/// Selector dependencies used to compute restyle hints.
dependencies: DependencySet,
/// The attribute local names that appear in attribute selectors. Used
/// to avoid taking element snapshots when an irrelevant attribute changes.
/// (We don't bother storing the namespace, since namespaced attributes
/// are rare.)
///
/// FIXME(heycam): This doesn't really need to be a counting Bloom filter.
#[cfg_attr(feature = "servo", ignore_heap_size_of = "just an array")]
attribute_dependencies: BloomFilter,
/// Whether `"style"` appears in an attribute selector. This is not common,
/// and by tracking this explicitly, we can avoid taking an element snapshot
/// in the common case of style=""` changing due to modifying
/// `element.style`. (We could track this in `attribute_dependencies`, like
/// all other attributes, but we should probably not risk incorrectly
/// returning `true` for `"style"` just due to a hash collision.)
style_attribute_dependency: bool,
/// Selectors that require explicit cache revalidation (i.e. which depend
/// on state that is not otherwise visible to the cache, like attributes or
/// tree-structural state like child index and pseudos).
@ -184,6 +201,8 @@ impl Stylist {
rules_source_order: 0,
rule_tree: RuleTree::new(),
dependencies: DependencySet::new(),
attribute_dependencies: BloomFilter::new(),
style_attribute_dependency: false,
selectors_for_cache_revalidation: SelectorMap::new(),
num_selectors: 0,
num_declarations: 0,
@ -254,6 +273,8 @@ impl Stylist {
self.rules_source_order = 0;
// We want to keep rule_tree around across stylist rebuilds.
self.dependencies.clear();
self.attribute_dependencies.clear();
self.style_attribute_dependency = false;
self.selectors_for_cache_revalidation = SelectorMap::new();
self.num_selectors = 0;
self.num_declarations = 0;
@ -375,6 +396,7 @@ impl Stylist {
self.add_rule_to_map(selector, locked, stylesheet);
self.dependencies.note_selector(selector);
self.note_for_revalidation(selector);
self.note_attribute_dependencies(selector);
}
self.rules_source_order += 1;
}
@ -434,6 +456,28 @@ impl Stylist {
}
}
/// Returns whether the given attribute might appear in an attribute
/// selector of some rule in the stylist.
pub fn might_have_attribute_dependency(&self,
local_name: &<SelectorImpl as ::selectors::SelectorImpl>::LocalName)
-> bool {
#[cfg(feature = "servo")]
let style_lower_name = local_name!("style");
#[cfg(feature = "gecko")]
let style_lower_name = atom!("style");
if *local_name == style_lower_name {
self.style_attribute_dependency
} else {
self.attribute_dependencies.might_contain(local_name)
}
}
#[inline]
fn note_attribute_dependencies(&mut self, selector: &Selector<SelectorImpl>) {
selector.visit(&mut AttributeDependencyVisitor(self));
}
/// Computes the style for a given "precomputed" pseudo-element, taking the
/// universal rules and applying them.
///
@ -962,6 +1006,28 @@ impl Drop for Stylist {
}
}
/// Visitor to collect names that appear in attribute selectors.
struct AttributeDependencyVisitor<'a>(&'a mut Stylist);
impl<'a> SelectorVisitor for AttributeDependencyVisitor<'a> {
type Impl = SelectorImpl;
fn visit_attribute_selector(&mut self, selector: &AttrSelector<Self::Impl>) -> bool {
#[cfg(feature = "servo")]
let style_lower_name = local_name!("style");
#[cfg(feature = "gecko")]
let style_lower_name = atom!("style");
if selector.lower_name == style_lower_name {
self.0.style_attribute_dependency = true;
} else {
self.0.attribute_dependencies.insert(&selector.name);
self.0.attribute_dependencies.insert(&selector.lower_name);
}
true
}
}
/// Visitor determine whether a selector requires cache revalidation.
///
/// Note that we just check simple selectors and eagerly return when the first

View file

@ -2331,3 +2331,10 @@ pub extern "C" fn Servo_StyleSet_ResolveForDeclarations(raw_data: RawServoStyleS
parent_style,
declarations.clone()).into_strong()
}
#[no_mangle]
pub extern "C" fn Servo_StyleSet_MightHaveAttributeDependency(raw_data: RawServoStyleSetBorrowed,
local_name: *mut nsIAtom) -> bool {
let data = PerDocumentStyleData::from_ffi(raw_data).borrow();
unsafe { Atom::with(local_name, &mut |atom| data.stylist.might_have_attribute_dependency(atom)) }
}