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style: Avoid multiple selector walk-ups during SelectorMap insertion.

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MozReview-Commit-ID: 5b2X0GL2753
Signed-off-by: Emilio Cobos Álvarez <emilio@crisal.io>
This commit is contained in:
Emilio Cobos Álvarez 2017-08-14 12:08:13 +02:00
parent dc654c9912
commit b040d79333
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GPG key ID: 056B727BB9C1027C
2 changed files with 92 additions and 127 deletions
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185
components/style/selector_map.rs
View file

@ -15,7 +15,6 @@ use rule_tree::CascadeLevel;
use selector_parser::SelectorImpl;
use selectors::matching::{matches_selector, MatchingContext, ElementSelectorFlags};
use selectors::parser::{Component, Combinator, SelectorIter};
use selectors::parser::LocalName as LocalNameSelector;
use smallvec::{SmallVec, VecLike};
use std::collections::{HashMap, HashSet};
use std::collections::hash_map;
@ -102,7 +101,7 @@ pub struct SelectorMap<T> {
/// A hash from local name to rules which contain that local name selector.
pub local_name_hash: PrecomputedHashMap<LocalName, SmallVec<[T; 1]>>,
/// Rules that don't have ID, class, or element selectors.
pub other: Vec<T>,
pub other: SmallVec<[T; 1]>,
/// The number of entries in this map.
pub count: usize,
}
@ -119,7 +118,7 @@ impl<T> SelectorMap<T> {
id_hash: MaybeCaseInsensitiveHashMap::new(),
class_hash: MaybeCaseInsensitiveHashMap::new(),
local_name_hash: HashMap::default(),
other: Vec::new(),
other: SmallVec::new(),
count: 0,
}
}
@ -231,37 +230,42 @@ impl<T: SelectorMapEntry> SelectorMap<T> {
pub fn insert(&mut self, entry: T, quirks_mode: QuirksMode) {
self.count += 1;
if let Some(id_name) = get_id_name(entry.selector()) {
self.id_hash.entry(id_name, quirks_mode).or_insert_with(SmallVec::new).push(entry);
return;
}
if let Some(class_name) = get_class_name(entry.selector()) {
self.class_hash.entry(class_name, quirks_mode).or_insert_with(SmallVec::new).push(entry);
return;
}
if let Some(LocalNameSelector { name, lower_name }) = get_local_name(entry.selector()) {
// If the local name in the selector isn't lowercase, insert it into
// the rule hash twice. This means that, during lookup, we can always
// find the rules based on the local name of the element, regardless
// of whether it's an html element in an html document (in which case
// we match against lower_name) or not (in which case we match against
// name).
//
// In the case of a non-html-element-in-html-document with a
// lowercase localname and a non-lowercase selector, the rulehash
// lookup may produce superfluous selectors, but the subsequent
// selector matching work will filter them out.
if name != lower_name {
find_push(&mut self.local_name_hash, lower_name, entry.clone());
let vector = match find_bucket(entry.selector()) {
Bucket::ID(id) => {
self.id_hash
.entry(id.clone(), quirks_mode)
.or_insert_with(SmallVec::new)
}
find_push(&mut self.local_name_hash, name, entry);
Bucket::Class(class) => {
self.class_hash
.entry(class.clone(), quirks_mode)
.or_insert_with(SmallVec::new)
}
Bucket::LocalName { name, lower_name } => {
// If the local name in the selector isn't lowercase, insert it
// into the rule hash twice. This means that, during lookup, we
// can always find the rules based on the local name of the
// element, regardless of whether it's an html element in an
// html document (in which case we match against lower_name) or
// not (in which case we match against name).
//
// In the case of a non-html-element-in-html-document with a
// lowercase localname and a non-lowercase selector, the
// rulehash lookup may produce superfluous selectors, but the
// subsequent selector matching work will filter them out.
if name != lower_name {
find_push(&mut self.local_name_hash, lower_name.clone(), entry.clone());
}
self.local_name_hash
.entry(name.clone())
.or_insert_with(SmallVec::new)
}
Bucket::Universal => {
&mut self.other
}
};
return;
}
self.other.push(entry);
vector.push(entry);
}
/// Looks up entries by id, class, local name, and other (in order).
@ -375,74 +379,65 @@ impl<T: SelectorMapEntry> SelectorMap<T> {
}
}
/// Searches a compound selector from left to right. If the compound selector
/// is a pseudo-element, it's ignored.
///
/// The first non-None value returned from |f| is returned.
#[inline(always)]
fn find_from_left<F, R>(
mut iter: SelectorIter<SelectorImpl>,
mut f: F
) -> Option<R>
where
F: FnMut(&Component<SelectorImpl>) -> Option<R>,
{
for ss in &mut iter {
if let Some(r) = f(ss) {
return Some(r)
}
}
enum Bucket<'a> {
ID(&'a Atom),
Class(&'a Atom),
LocalName { name: &'a LocalName, lower_name: &'a LocalName, },
Universal,
}
// Effectively, pseudo-elements are ignored, given only state pseudo-classes
// may appear before them.
if iter.next_sequence() == Some(Combinator::PseudoElement) {
for ss in &mut iter {
if let Some(r) = f(ss) {
return Some(r)
fn specific_bucket_for<'a>(
component: &'a Component<SelectorImpl>
) -> Bucket<'a> {
match *component {
Component::ID(ref id) => Bucket::ID(id),
Component::Class(ref class) => Bucket::Class(class),
Component::LocalName(ref selector) => {
Bucket::LocalName {
name: &selector.name,
lower_name: &selector.lower_name,
}
}
_ => Bucket::Universal
}
}
/// Searches a compound selector from left to right, and returns the appropriate
/// bucket for it.
#[inline(always)]
fn find_bucket<'a>(mut iter: SelectorIter<'a, SelectorImpl>) -> Bucket<'a> {
let mut current_bucket = Bucket::Universal;
loop {
// We basically want to find the most specific bucket,
// where:
//
// id > class > local name > universal.
//
for ss in &mut iter {
let new_bucket = specific_bucket_for(ss);
match new_bucket {
Bucket::ID(..) => return new_bucket,
Bucket::Class(..) => {
current_bucket = new_bucket;
}
Bucket::LocalName { .. } => {
if matches!(current_bucket, Bucket::Universal) {
current_bucket = new_bucket;
}
}
Bucket::Universal => {},
}
}
// Effectively, pseudo-elements are ignored, given only state
// pseudo-classes may appear before them.
if iter.next_sequence() != Some(Combinator::PseudoElement) {
break;
}
}
None
}
/// Retrieve the first ID name in the selector, or None otherwise.
#[inline(always)]
pub fn get_id_name(iter: SelectorIter<SelectorImpl>)
-> Option<Atom> {
find_from_left(iter, |ss| {
if let Component::ID(ref id) = *ss {
return Some(id.clone());
}
None
})
}
/// Retrieve the FIRST class name in the selector, or None otherwise.
#[inline(always)]
pub fn get_class_name(iter: SelectorIter<SelectorImpl>)
-> Option<Atom> {
find_from_left(iter, |ss| {
if let Component::Class(ref class) = *ss {
return Some(class.clone());
}
None
})
}
/// Retrieve the name if it is a type selector, or None otherwise.
#[inline(always)]
pub fn get_local_name(iter: SelectorIter<SelectorImpl>)
-> Option<LocalNameSelector<SelectorImpl>> {
find_from_left(iter, |ss| {
if let Component::LocalName(ref n) = *ss {
return Some(LocalNameSelector {
name: n.name.clone(),
lower_name: n.lower_name.clone(),
})
}
None
})
return current_bucket
}
#[inline]

34
tests/unit/style/stylist.rs
View file

@ -167,36 +167,6 @@ fn test_rule_ordering_same_specificity() {
"The rule that comes later should win.");
}
#[test]
fn test_get_id_name() {
let (rules_list, _) = get_mock_rules(&[".intro", "#top"]);
assert_eq!(selector_map::get_id_name(rules_list[0][0].selector.iter()), None);
assert_eq!(selector_map::get_id_name(rules_list[1][0].selector.iter()), Some(Atom::from("top")));
}
#[test]
fn test_get_class_name() {
let (rules_list, _) = get_mock_rules(&[".intro.foo", "#top"]);
assert_eq!(selector_map::get_class_name(rules_list[0][0].selector.iter()), Some(Atom::from("intro")));
assert_eq!(selector_map::get_class_name(rules_list[1][0].selector.iter()), None);
}
#[test]
fn test_get_local_name() {
let (rules_list, _) = get_mock_rules(&["img.foo", "#top", "IMG", "ImG"]);
let check = |i: usize, names: Option<(&str, &str)>| {
assert!(selector_map::get_local_name(rules_list[i][0].selector.iter())
== names.map(|(name, lower_name)| LocalNameSelector {
name: LocalName::from(name),
lower_name: LocalName::from(lower_name) }))
};
check(0, Some(("img", "img")));
check(1, None);
check(2, Some(("IMG", "img")));
check(3, Some(("ImG", "img")));
}
#[test]
fn test_insert() {
let (rules_list, _) = get_mock_rules(&[".intro.foo", "#top"]);
@ -204,8 +174,8 @@ fn test_insert() {
selector_map.insert(rules_list[1][0].clone(), QuirksMode::NoQuirks);
assert_eq!(1, selector_map.id_hash.get(&Atom::from("top"), QuirksMode::NoQuirks).unwrap()[0].source_order);
selector_map.insert(rules_list[0][0].clone(), QuirksMode::NoQuirks);
assert_eq!(0, selector_map.class_hash.get(&Atom::from("intro"), QuirksMode::NoQuirks).unwrap()[0].source_order);
assert!(selector_map.class_hash.get(&Atom::from("foo"), QuirksMode::NoQuirks).is_none());
assert_eq!(0, selector_map.class_hash.get(&Atom::from("foo"), QuirksMode::NoQuirks).unwrap()[0].source_order);
assert!(selector_map.class_hash.get(&Atom::from("intro"), QuirksMode::NoQuirks).is_none());
}
fn mock_stylist() -> Stylist {