/
matching.rs
960 lines (851 loc) · 39.9 KB
/
matching.rs
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/* 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 http://mozilla.org/MPL/2.0/. */
//! High-level interface to CSS selector matching.
#![allow(unsafe_code)]
#![deny(missing_docs)]
use {Atom, LocalName};
use animation::{self, Animation, PropertyAnimation};
use atomic_refcell::AtomicRefMut;
use cache::LRUCache;
use cascade_info::CascadeInfo;
use context::{SharedStyleContext, StyleContext};
use data::{ComputedStyle, ElementData, ElementStyles, PseudoStyles};
use dom::{SendElement, TElement, TNode};
use properties::{CascadeFlags, ComputedValues, SHAREABLE, SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP, cascade};
use properties::longhands::display::computed_value as display;
use rule_tree::StrongRuleNode;
use selector_parser::{PseudoElement, RestyleDamage, SelectorImpl};
use selectors::MatchAttr;
use selectors::bloom::BloomFilter;
use selectors::matching::{AFFECTED_BY_PSEUDO_ELEMENTS, MatchingReason, StyleRelations};
use servo_config::opts;
use sink::ForgetfulSink;
use std::collections::HashMap;
use std::hash::BuildHasherDefault;
use std::slice::IterMut;
use std::sync::Arc;
use stylist::ApplicableDeclarationBlock;
/// Determines the amount of relations where we're going to share style.
#[inline]
fn relations_are_shareable(relations: &StyleRelations) -> bool {
use selectors::matching::*;
!relations.intersects(AFFECTED_BY_ID_SELECTOR |
AFFECTED_BY_PSEUDO_ELEMENTS | AFFECTED_BY_STATE |
AFFECTED_BY_STYLE_ATTRIBUTE |
AFFECTED_BY_PRESENTATIONAL_HINTS)
}
fn create_common_style_affecting_attributes_from_element<E: TElement>(element: &E)
-> CommonStyleAffectingAttributes {
let mut flags = CommonStyleAffectingAttributes::empty();
for attribute_info in &common_style_affecting_attributes() {
match attribute_info.mode {
CommonStyleAffectingAttributeMode::IsPresent(flag) => {
if element.has_attr(&ns!(), &attribute_info.attr_name) {
flags.insert(flag)
}
}
CommonStyleAffectingAttributeMode::IsEqual(ref target_value, flag) => {
if element.attr_equals(&ns!(), &attribute_info.attr_name, target_value) {
flags.insert(flag)
}
}
}
}
flags
}
/// The rule nodes for each of the pseudo-elements of an element.
///
/// TODO(emilio): Probably shouldn't be a `HashMap` by default, but a smaller
/// array.
type PseudoRuleNodes = HashMap<PseudoElement, StrongRuleNode,
BuildHasherDefault<::fnv::FnvHasher>>;
/// The results of selector matching on an element.
pub struct MatchResults {
/// The rule node reference that represents the rules matched by the
/// element.
pub primary: StrongRuleNode,
/// A set of style relations (different hints about what rules matched or
/// could have matched).
pub relations: StyleRelations,
/// The results of selector-matching the pseudo-elements.
pub per_pseudo: PseudoRuleNodes,
}
impl MatchResults {
/// Returns true if the primary rule node is shareable with other nodes.
pub fn primary_is_shareable(&self) -> bool {
relations_are_shareable(&self.relations)
}
}
/// Information regarding a style sharing candidate.
///
/// Note that this information is stored in TLS and cleared after the traversal,
/// and once here, the style information of the element is immutable, so it's
/// safe to access.
///
/// TODO: We can stick a lot more info here.
#[derive(Debug)]
struct StyleSharingCandidate<E: TElement> {
/// The element. We use SendElement here so that the cache may live in
/// ScopedTLS.
element: SendElement<E>,
/// The cached common style affecting attribute info.
common_style_affecting_attributes: Option<CommonStyleAffectingAttributes>,
/// The cached class names.
class_attributes: Option<Vec<Atom>>,
}
impl<E: TElement> PartialEq<StyleSharingCandidate<E>> for StyleSharingCandidate<E> {
fn eq(&self, other: &Self) -> bool {
self.element == other.element &&
self.common_style_affecting_attributes == other.common_style_affecting_attributes
}
}
/// An LRU cache of the last few nodes seen, so that we can aggressively try to
/// reuse their styles.
///
/// Note that this cache is flushed every time we steal work from the queue, so
/// storing nodes here temporarily is safe.
pub struct StyleSharingCandidateCache<E: TElement> {
cache: LRUCache<StyleSharingCandidate<E>, ()>,
}
/// A cache miss result.
#[derive(Clone, Debug)]
pub enum CacheMiss {
/// The parents don't match.
Parent,
/// The local name of the element and the candidate don't match.
LocalName,
/// The namespace of the element and the candidate don't match.
Namespace,
/// One of the element or the candidate was a link, but the other one
/// wasn't.
Link,
/// The element and the candidate match different kind of rules. This can
/// only happen in Gecko.
UserAndAuthorRules,
/// The element and the candidate are in a different state.
State,
/// The element had an id attribute, which qualifies for a unique style.
IdAttr,
/// The element had a style attribute, which qualifies for a unique style.
StyleAttr,
/// The element and the candidate class names didn't match.
Class,
/// The element and the candidate common style affecting attributes didn't
/// match.
CommonStyleAffectingAttributes,
/// The presentation hints didn't match.
PresHints,
/// The element and the candidate didn't match the same set of
/// sibling-affecting rules.
SiblingRules,
/// The element and the candidate didn't match the same set of non-common
/// style affecting attribute selectors.
NonCommonAttrRules,
}
fn element_matches_candidate<E: TElement>(element: &E,
candidate: &mut StyleSharingCandidate<E>,
candidate_element: &E,
shared_context: &SharedStyleContext)
-> Result<ComputedStyle, CacheMiss> {
macro_rules! miss {
($miss: ident) => {
return Err(CacheMiss::$miss);
}
}
if element.parent_element() != candidate_element.parent_element() {
miss!(Parent)
}
if *element.get_local_name() != *candidate_element.get_local_name() {
miss!(LocalName)
}
if *element.get_namespace() != *candidate_element.get_namespace() {
miss!(Namespace)
}
if element.is_link() != candidate_element.is_link() {
miss!(Link)
}
if element.matches_user_and_author_rules() != candidate_element.matches_user_and_author_rules() {
miss!(UserAndAuthorRules)
}
if element.get_state() != candidate_element.get_state() {
miss!(State)
}
if element.get_id().is_some() {
miss!(IdAttr)
}
if element.style_attribute().is_some() {
miss!(StyleAttr)
}
if !have_same_class(element, candidate, candidate_element) {
miss!(Class)
}
if !have_same_common_style_affecting_attributes(element,
candidate,
candidate_element) {
miss!(CommonStyleAffectingAttributes)
}
if !have_same_presentational_hints(element, candidate_element) {
miss!(PresHints)
}
if !match_same_sibling_affecting_rules(element,
candidate_element,
shared_context) {
miss!(SiblingRules)
}
if !match_same_not_common_style_affecting_attributes_rules(element,
candidate_element,
shared_context) {
miss!(NonCommonAttrRules)
}
let data = candidate_element.borrow_data().unwrap();
debug_assert!(data.has_current_styles());
let current_styles = data.styles();
Ok(current_styles.primary.clone())
}
fn have_same_common_style_affecting_attributes<E: TElement>(element: &E,
candidate: &mut StyleSharingCandidate<E>,
candidate_element: &E) -> bool {
if candidate.common_style_affecting_attributes.is_none() {
candidate.common_style_affecting_attributes =
Some(create_common_style_affecting_attributes_from_element(candidate_element))
}
create_common_style_affecting_attributes_from_element(element) ==
candidate.common_style_affecting_attributes.unwrap()
}
fn have_same_presentational_hints<E: TElement>(element: &E, candidate: &E) -> bool {
let mut first = ForgetfulSink::new();
element.synthesize_presentational_hints_for_legacy_attributes(&mut first);
if cfg!(debug_assertions) {
let mut second = vec![];
candidate.synthesize_presentational_hints_for_legacy_attributes(&mut second);
debug_assert!(second.is_empty(),
"Should never have inserted an element with preshints in the cache!");
}
first.is_empty()
}
bitflags! {
/// A set of common style-affecting attributes we check separately to
/// optimize the style sharing cache.
pub flags CommonStyleAffectingAttributes: u8 {
/// The `hidden` attribute.
const HIDDEN_ATTRIBUTE = 0x01,
/// The `nowrap` attribute.
const NO_WRAP_ATTRIBUTE = 0x02,
/// The `align="left"` attribute.
const ALIGN_LEFT_ATTRIBUTE = 0x04,
/// The `align="center"` attribute.
const ALIGN_CENTER_ATTRIBUTE = 0x08,
/// The `align="right"` attribute.
const ALIGN_RIGHT_ATTRIBUTE = 0x10,
}
}
/// The information of how to match a given common-style affecting attribute.
pub struct CommonStyleAffectingAttributeInfo {
/// The attribute name.
pub attr_name: LocalName,
/// The matching mode for the attribute.
pub mode: CommonStyleAffectingAttributeMode,
}
/// How should we match a given common style-affecting attribute?
#[derive(Clone)]
pub enum CommonStyleAffectingAttributeMode {
/// Just for presence?
IsPresent(CommonStyleAffectingAttributes),
/// For presence and equality with a given value.
IsEqual(Atom, CommonStyleAffectingAttributes),
}
/// The common style affecting attribute array.
///
/// TODO: This should be a `const static` or similar, but couldn't be because
/// `Atom`s have destructors.
#[inline]
pub fn common_style_affecting_attributes() -> [CommonStyleAffectingAttributeInfo; 5] {
[
CommonStyleAffectingAttributeInfo {
attr_name: local_name!("hidden"),
mode: CommonStyleAffectingAttributeMode::IsPresent(HIDDEN_ATTRIBUTE),
},
CommonStyleAffectingAttributeInfo {
attr_name: local_name!("nowrap"),
mode: CommonStyleAffectingAttributeMode::IsPresent(NO_WRAP_ATTRIBUTE),
},
CommonStyleAffectingAttributeInfo {
attr_name: local_name!("align"),
mode: CommonStyleAffectingAttributeMode::IsEqual(atom!("left"), ALIGN_LEFT_ATTRIBUTE),
},
CommonStyleAffectingAttributeInfo {
attr_name: local_name!("align"),
mode: CommonStyleAffectingAttributeMode::IsEqual(atom!("center"), ALIGN_CENTER_ATTRIBUTE),
},
CommonStyleAffectingAttributeInfo {
attr_name: local_name!("align"),
mode: CommonStyleAffectingAttributeMode::IsEqual(atom!("right"), ALIGN_RIGHT_ATTRIBUTE),
}
]
}
/// Attributes that, if present, disable style sharing. All legacy HTML
/// attributes must be in either this list or
/// `common_style_affecting_attributes`. See the comment in
/// `synthesize_presentational_hints_for_legacy_attributes`.
///
/// TODO(emilio): This is not accurate now, we don't disable style sharing for
/// this now since we check for attribute selectors in the stylesheet. Consider
/// removing this.
pub fn rare_style_affecting_attributes() -> [LocalName; 4] {
[local_name!("bgcolor"), local_name!("border"), local_name!("colspan"), local_name!("rowspan")]
}
fn have_same_class<E: TElement>(element: &E,
candidate: &mut StyleSharingCandidate<E>,
candidate_element: &E) -> bool {
// XXX Efficiency here, I'm only validating ideas.
let mut element_class_attributes = vec![];
element.each_class(|c| element_class_attributes.push(c.clone()));
if candidate.class_attributes.is_none() {
let mut attrs = vec![];
candidate_element.each_class(|c| attrs.push(c.clone()));
candidate.class_attributes = Some(attrs)
}
element_class_attributes == *candidate.class_attributes.as_ref().unwrap()
}
// TODO: These re-match the candidate every time, which is suboptimal.
#[inline]
fn match_same_not_common_style_affecting_attributes_rules<E: TElement>(element: &E,
candidate: &E,
ctx: &SharedStyleContext) -> bool {
ctx.stylist.match_same_not_common_style_affecting_attributes_rules(element, candidate)
}
#[inline]
fn match_same_sibling_affecting_rules<E: TElement>(element: &E,
candidate: &E,
ctx: &SharedStyleContext) -> bool {
ctx.stylist.match_same_sibling_affecting_rules(element, candidate)
}
static STYLE_SHARING_CANDIDATE_CACHE_SIZE: usize = 8;
impl<E: TElement> StyleSharingCandidateCache<E> {
/// Create a new style sharing candidate cache.
pub fn new() -> Self {
StyleSharingCandidateCache {
cache: LRUCache::new(STYLE_SHARING_CANDIDATE_CACHE_SIZE),
}
}
fn iter_mut(&mut self) -> IterMut<(StyleSharingCandidate<E>, ())> {
self.cache.iter_mut()
}
/// Tries to insert an element in the style sharing cache.
///
/// Fails if we know it should never be in the cache.
pub fn insert_if_possible(&mut self,
element: &E,
style: &Arc<ComputedValues>,
relations: StyleRelations) {
let parent = match element.parent_element() {
Some(element) => element,
None => {
debug!("Failing to insert to the cache: no parent element");
return;
}
};
// These are things we don't check in the candidate match because they
// are either uncommon or expensive.
if !relations_are_shareable(&relations) {
debug!("Failing to insert to the cache: {:?}", relations);
return;
}
let box_style = style.get_box();
if box_style.transition_property_count() > 0 {
debug!("Failing to insert to the cache: transitions");
return;
}
if box_style.animation_name_count() > 0 {
debug!("Failing to insert to the cache: animations");
return;
}
debug!("Inserting into cache: {:?} with parent {:?}",
element, parent);
self.cache.insert(StyleSharingCandidate {
element: unsafe { SendElement::new(*element) },
common_style_affecting_attributes: None,
class_attributes: None,
}, ());
}
/// Touch a given index in the style sharing candidate cache.
pub fn touch(&mut self, index: usize) {
self.cache.touch(index);
}
/// Clear the style sharing candidate cache.
pub fn clear(&mut self) {
self.cache.evict_all()
}
}
/// The results of attempting to share a style.
pub enum StyleSharingResult {
/// We didn't find anybody to share the style with.
CannotShare,
/// The node's style can be shared. The integer specifies the index in the
/// LRU cache that was hit and the damage that was done.
StyleWasShared(usize),
}
/// Callers need to pass several boolean flags to cascade_node_pseudo_element.
/// We encapsulate them in this struct to avoid mixing them up.
///
/// FIXME(pcwalton): Unify with `CascadeFlags`, perhaps?
struct CascadeBooleans {
shareable: bool,
animate: bool,
}
trait PrivateMatchMethods: TElement {
/// Actually cascades style for a node or a pseudo-element of a node.
///
/// Note that animations only apply to nodes or ::before or ::after
/// pseudo-elements.
fn cascade_node_pseudo_element<'a>(&self,
context: &StyleContext<Self>,
parent_style: Option<&Arc<ComputedValues>>,
old_style: Option<&Arc<ComputedValues>>,
rule_node: &StrongRuleNode,
possibly_expired_animations: &[PropertyAnimation],
booleans: CascadeBooleans)
-> Arc<ComputedValues> {
let shared_context = context.shared;
let mut cascade_info = CascadeInfo::new();
let mut cascade_flags = CascadeFlags::empty();
if booleans.shareable {
cascade_flags.insert(SHAREABLE)
}
if self.skip_root_and_item_based_display_fixup() {
cascade_flags.insert(SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP)
}
let this_style = match parent_style {
Some(ref parent_style) => {
cascade(shared_context.viewport_size,
rule_node,
Some(&***parent_style),
&shared_context.default_computed_values,
Some(&mut cascade_info),
shared_context.error_reporter.clone(),
cascade_flags)
}
None => {
cascade(shared_context.viewport_size,
rule_node,
None,
&shared_context.default_computed_values,
Some(&mut cascade_info),
shared_context.error_reporter.clone(),
cascade_flags)
}
};
cascade_info.finish(&self.as_node());
let mut this_style = Arc::new(this_style);
if booleans.animate {
let new_animations_sender = &context.thread_local.new_animations_sender;
let this_opaque = self.as_node().opaque();
// Trigger any present animations if necessary.
animation::maybe_start_animations(&shared_context,
new_animations_sender,
this_opaque, &this_style);
// Trigger transitions if necessary. This will reset `this_style` back
// to its old value if it did trigger a transition.
if let Some(ref style) = old_style {
animation::start_transitions_if_applicable(
new_animations_sender,
this_opaque,
self.as_node().to_unsafe(),
&**style,
&mut this_style,
&shared_context.timer,
&possibly_expired_animations);
}
}
this_style
}
fn update_animations_for_cascade(&self,
context: &SharedStyleContext,
style: &mut Arc<ComputedValues>,
possibly_expired_animations: &mut Vec<PropertyAnimation>) {
// Finish any expired transitions.
let this_opaque = self.as_node().opaque();
animation::complete_expired_transitions(this_opaque, style, context);
// Merge any running transitions into the current style, and cancel them.
let had_running_animations = context.running_animations
.read()
.get(&this_opaque)
.is_some();
if had_running_animations {
let mut all_running_animations = context.running_animations.write();
for running_animation in all_running_animations.get_mut(&this_opaque).unwrap() {
// This shouldn't happen frequently, but under some
// circumstances mainly huge load or debug builds, the
// constellation might be delayed in sending the
// `TickAllAnimations` message to layout.
//
// Thus, we can't assume all the animations have been already
// updated by layout, because other restyle due to script might
// be triggered by layout before the animation tick.
//
// See #12171 and the associated PR for an example where this
// happened while debugging other release panic.
if !running_animation.is_expired() {
animation::update_style_for_animation(context,
running_animation,
style);
if let Animation::Transition(_, _, _, ref frame, _) = *running_animation {
possibly_expired_animations.push(frame.property_animation.clone())
}
}
}
}
}
fn share_style_with_candidate_if_possible(&self,
shared_context: &SharedStyleContext,
candidate: &mut StyleSharingCandidate<Self>)
-> Result<ComputedStyle, CacheMiss> {
let candidate_element = *candidate.element;
element_matches_candidate(self, candidate, &candidate_element, shared_context)
}
}
fn compute_rule_node<E: TElement>(context: &StyleContext<E>,
applicable_declarations: &mut Vec<ApplicableDeclarationBlock>)
-> StrongRuleNode
{
let rules = applicable_declarations.drain(..).map(|d| (d.source, d.importance));
let rule_node = context.shared.stylist.rule_tree.insert_ordered_rules(rules);
rule_node
}
impl<E: TElement> PrivateMatchMethods for E {}
/// The public API that elements expose for selector matching.
pub trait MatchMethods : TElement {
/// Runs selector matching of this element, and returns the result.
fn match_element(&self, context: &StyleContext<Self>, parent_bf: Option<&BloomFilter>)
-> MatchResults
{
let mut applicable_declarations: Vec<ApplicableDeclarationBlock> = Vec::with_capacity(16);
let stylist = &context.shared.stylist;
let style_attribute = self.style_attribute();
let animation_rules = self.get_animation_rules(None);
// Compute the primary rule node.
let mut primary_relations =
stylist.push_applicable_declarations(self,
parent_bf,
style_attribute,
animation_rules,
None,
&mut applicable_declarations,
MatchingReason::ForStyling);
let primary_rule_node = compute_rule_node(context, &mut applicable_declarations);
// Compute the pseudo rule nodes.
let mut per_pseudo: PseudoRuleNodes = HashMap::with_hasher(Default::default());
SelectorImpl::each_eagerly_cascaded_pseudo_element(|pseudo| {
debug_assert!(applicable_declarations.is_empty());
let pseudo_animation_rules = self.get_animation_rules(Some(&pseudo));
stylist.push_applicable_declarations(self, parent_bf, None,
pseudo_animation_rules,
Some(&pseudo.clone()),
&mut applicable_declarations,
MatchingReason::ForStyling);
if !applicable_declarations.is_empty() {
let rule_node = compute_rule_node(context, &mut applicable_declarations);
per_pseudo.insert(pseudo, rule_node);
}
});
// If we have any pseudo elements, indicate so in the primary StyleRelations.
if !per_pseudo.is_empty() {
primary_relations |= AFFECTED_BY_PSEUDO_ELEMENTS;
}
MatchResults {
primary: primary_rule_node,
relations: primary_relations,
per_pseudo: per_pseudo,
}
}
/// Attempts to share a style with another node. This method is unsafe
/// because it depends on the `style_sharing_candidate_cache` having only
/// live nodes in it, and we have no way to guarantee that at the type
/// system level yet.
unsafe fn share_style_if_possible(&self,
style_sharing_candidate_cache:
&mut StyleSharingCandidateCache<Self>,
shared_context: &SharedStyleContext,
data: &mut AtomicRefMut<ElementData>)
-> StyleSharingResult {
if opts::get().disable_share_style_cache {
return StyleSharingResult::CannotShare
}
if self.style_attribute().is_some() {
return StyleSharingResult::CannotShare
}
if self.has_attr(&ns!(), &local_name!("id")) {
return StyleSharingResult::CannotShare
}
let mut should_clear_cache = false;
for (i, &mut (ref mut candidate, ())) in style_sharing_candidate_cache.iter_mut().enumerate() {
let sharing_result = self.share_style_with_candidate_if_possible(shared_context, candidate);
match sharing_result {
Ok(shared_style) => {
// Yay, cache hit. Share the style.
// TODO: add the display: none optimisation here too! Even
// better, factor it out/make it a bit more generic so Gecko
// can decide more easily if it knows that it's a child of
// replaced content, or similar stuff!
let maybe_damage = {
let previous = data.get_styles().map(|x| &x.primary.values);
let existing = self.existing_style_for_restyle_damage(previous, None);
existing.map(|e| RestyleDamage::compute(e, &shared_style.values))
};
if let Some(d) = maybe_damage {
data.restyle_mut().damage |= d;
}
// We never put elements with pseudo style into the style sharing cache,
// so we can just mint an ElementStyles directly here.
//
// See https://bugzilla.mozilla.org/show_bug.cgi?id=1329361
let styles = ElementStyles::new(shared_style);
data.set_styles(styles);
return StyleSharingResult::StyleWasShared(i)
}
Err(miss) => {
debug!("Cache miss: {:?}", miss);
// Cache miss, let's see what kind of failure to decide
// whether we keep trying or not.
match miss {
// Cache miss because of parent, clear the candidate cache.
CacheMiss::Parent => {
should_clear_cache = true;
break;
},
// Too expensive failure, give up, we don't want another
// one of these.
CacheMiss::CommonStyleAffectingAttributes |
CacheMiss::PresHints |
CacheMiss::SiblingRules |
CacheMiss::NonCommonAttrRules => break,
_ => {}
}
}
}
}
if should_clear_cache {
style_sharing_candidate_cache.clear();
}
StyleSharingResult::CannotShare
}
// The below two functions are copy+paste because I can't figure out how to
// write a function which takes a generic function. I don't think it can
// be done.
//
// Ideally, I'd want something like:
//
// > fn with_really_simple_selectors(&self, f: <H: Hash>|&H|);
// In terms of `SimpleSelector`s, these two functions will insert and remove:
// - `SimpleSelector::LocalName`
// - `SimpleSelector::Namepace`
// - `SimpleSelector::ID`
// - `SimpleSelector::Class`
/// Inserts and removes the matching `Descendant` selectors from a bloom
/// filter. This is used to speed up CSS selector matching to remove
/// unnecessary tree climbs for `Descendant` queries.
///
/// A bloom filter of the local names, namespaces, IDs, and classes is kept.
/// Therefore, each node must have its matching selectors inserted _after_
/// its own selector matching and _before_ its children start.
fn insert_into_bloom_filter(&self, bf: &mut BloomFilter) {
bf.insert(&*self.get_local_name());
bf.insert(&*self.get_namespace());
self.get_id().map(|id| bf.insert(&id));
// TODO: case-sensitivity depends on the document type and quirks mode
self.each_class(|class| bf.insert(class));
}
/// After all the children are done css selector matching, this must be
/// called to reset the bloom filter after an `insert`.
fn remove_from_bloom_filter(&self, bf: &mut BloomFilter) {
bf.remove(&*self.get_local_name());
bf.remove(&*self.get_namespace());
self.get_id().map(|id| bf.remove(&id));
// TODO: case-sensitivity depends on the document type and quirks mode
self.each_class(|class| bf.remove(class));
}
/// Given the old and new style of this element, and whether it's a
/// pseudo-element, compute the restyle damage used to determine which
/// kind of layout or painting operations we'll need.
fn compute_restyle_damage(&self,
old_style: Option<&Arc<ComputedValues>>,
new_style: &Arc<ComputedValues>,
pseudo: Option<&PseudoElement>)
-> RestyleDamage
{
match self.existing_style_for_restyle_damage(old_style, pseudo) {
Some(ref source) => RestyleDamage::compute(source, new_style),
None => {
// If there's no style source, two things can happen:
//
// 1. This is not an incremental restyle (old_style is none).
// In this case we can't do too much than sending
// rebuild_and_reflow.
//
// 2. This is an incremental restyle, but the old display value
// is none, so there's no effective way for Gecko to get the
// style source (which is the style context).
//
// In this case, we could return either
// RestyleDamage::empty(), in the case both displays are
// none, or rebuild_and_reflow, otherwise.
//
if let Some(old_style) = old_style {
// FIXME(emilio): This should assert the old style is
// display: none, but we still can't get an old style
// context for other stuff that should give us a style
// context source like display: contents, so we fall on the
// safe side here.
if new_style.get_box().clone_display() == display::T::none &&
old_style.get_box().clone_display() == display::T::none {
return RestyleDamage::empty();
}
}
RestyleDamage::rebuild_and_reflow()
}
}
}
/// Given the results of selector matching, run the CSS cascade and style
/// the node, potentially starting any new transitions or animations.
fn cascade_node(&self,
context: &StyleContext<Self>,
mut data: &mut AtomicRefMut<ElementData>,
parent: Option<Self>,
primary_rule_node: StrongRuleNode,
pseudo_rule_nodes: PseudoRuleNodes,
primary_is_shareable: bool)
{
// Get our parent's style.
let parent_data = parent.as_ref().map(|x| x.borrow_data().unwrap());
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") || d.has_current_styles());
&d.styles().primary.values
});
let mut new_styles;
let mut possibly_expired_animations = vec![];
let damage = {
debug_assert!(!data.has_current_styles());
let (old_primary, old_pseudos) = match data.get_styles_mut() {
None => (None, None),
Some(previous) => {
// Update animations before the cascade. This may modify the
// value of the old primary style.
self.update_animations_for_cascade(&context.shared,
&mut previous.primary.values,
&mut possibly_expired_animations);
(Some(&previous.primary.values), Some(&mut previous.pseudos))
}
};
let new_style =
self.cascade_node_pseudo_element(context,
parent_style,
old_primary,
&primary_rule_node,
&possibly_expired_animations,
CascadeBooleans {
shareable: primary_is_shareable,
animate: true,
});
let primary = ComputedStyle::new(primary_rule_node, new_style);
new_styles = ElementStyles::new(primary);
let damage =
self.compute_damage_and_cascade_pseudos(old_primary,
old_pseudos,
&new_styles.primary.values,
&mut new_styles.pseudos,
context,
pseudo_rule_nodes,
&mut possibly_expired_animations);
unsafe {
self.as_node().set_can_be_fragmented(parent.map_or(false, |p| {
p.as_node().can_be_fragmented() ||
parent_style.unwrap().is_multicol()
}));
}
damage
};
if data.has_styles() {
data.restyle_mut().damage |= damage;
}
data.set_styles(new_styles);
}
/// Given the old and new styling results, compute the final restyle damage.
fn compute_damage_and_cascade_pseudos(
&self,
old_primary: Option<&Arc<ComputedValues>>,
mut old_pseudos: Option<&mut PseudoStyles>,
new_primary: &Arc<ComputedValues>,
new_pseudos: &mut PseudoStyles,
context: &StyleContext<Self>,
mut pseudo_rule_nodes: PseudoRuleNodes,
possibly_expired_animations: &mut Vec<PropertyAnimation>)
-> RestyleDamage
{
// Compute the damage and sum up the damage related to pseudo-elements.
let mut damage =
self.compute_restyle_damage(old_primary, new_primary, None);
// If the new style is display:none, we don't need pseudo-elements styles.
if new_primary.get_box().clone_display() == display::T::none {
return damage;
}
let rebuild_and_reflow = RestyleDamage::rebuild_and_reflow();
debug_assert!(new_pseudos.is_empty());
<Self as MatchAttr>::Impl::each_eagerly_cascaded_pseudo_element(|pseudo| {
let maybe_rule_node = pseudo_rule_nodes.remove(&pseudo);
// Grab the old pseudo style for analysis.
let mut maybe_old_pseudo_style =
old_pseudos.as_mut().and_then(|x| x.remove(&pseudo));
if maybe_rule_node.is_some() {
let new_rule_node = maybe_rule_node.unwrap();
// We have declarations, so we need to cascade. Compute parameters.
let animate = <Self as MatchAttr>::Impl::pseudo_is_before_or_after(&pseudo);
if animate {
if let Some(ref mut old_pseudo_style) = maybe_old_pseudo_style {
// Update animations before the cascade. This may modify
// the value of old_pseudo_style.
self.update_animations_for_cascade(&context.shared,
&mut old_pseudo_style.values,
possibly_expired_animations);
}
}
let new_pseudo_values =
self.cascade_node_pseudo_element(context,
Some(new_primary),
maybe_old_pseudo_style.as_ref()
.map(|s| &s.values),
&new_rule_node,
&possibly_expired_animations,
CascadeBooleans {
shareable: false,
animate: animate,
});
// Compute restyle damage unless we've already maxed it out.
if damage != rebuild_and_reflow {
damage = damage | match maybe_old_pseudo_style {
None => rebuild_and_reflow,
Some(ref old) => self.compute_restyle_damage(Some(&old.values),
&new_pseudo_values,
Some(&pseudo)),
};
}
// Insert the new entry into the map.
let new_pseudo_style = ComputedStyle::new(new_rule_node, new_pseudo_values);
let existing = new_pseudos.insert(pseudo, new_pseudo_style);
debug_assert!(existing.is_none());
} else {
if maybe_old_pseudo_style.is_some() {
damage = rebuild_and_reflow;
}
}
});
damage
}
}
impl<E: TElement> MatchMethods for E {}