mirror of
https://github.com/servo/servo.git
synced 2025-06-06 16:45:39 +00:00
558 lines
21 KiB
Rust
558 lines
21 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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// High-level interface to CSS selector matching.
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use css::node_style::StyledNode;
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use construct::FlowConstructor;
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use context::LayoutContext;
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use extra::LayoutAuxMethods;
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use util::{LayoutDataAccess, LayoutDataWrapper};
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use wrapper::{LayoutElement, LayoutNode, PostorderNodeMutTraversal, ThreadSafeLayoutNode};
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use servo_util::atom::Atom;
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use servo_util::cache::{Cache, LRUCache, SimpleHashCache};
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use servo_util::namespace::Null;
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use servo_util::smallvec::{SmallVec, SmallVec16};
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use servo_util::str::DOMString;
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use std::mem;
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use std::hash::{Hash, sip};
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use std::slice::Items;
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use style::{After, Before, ComputedValues, DeclarationBlock, Stylist, TElement, TNode, cascade};
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use sync::Arc;
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pub struct ApplicableDeclarations {
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pub normal: SmallVec16<DeclarationBlock>,
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pub before: Vec<DeclarationBlock>,
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pub after: Vec<DeclarationBlock>,
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/// Whether the `normal` declarations are shareable with other nodes.
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pub normal_shareable: bool,
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}
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impl ApplicableDeclarations {
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pub fn new() -> ApplicableDeclarations {
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ApplicableDeclarations {
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normal: SmallVec16::new(),
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before: Vec::new(),
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after: Vec::new(),
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normal_shareable: false,
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}
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}
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pub fn clear(&mut self) {
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self.normal = SmallVec16::new();
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self.before = Vec::new();
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self.after = Vec::new();
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self.normal_shareable = false;
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}
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}
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#[deriving(Clone)]
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pub struct ApplicableDeclarationsCacheEntry {
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pub declarations: Vec<DeclarationBlock>,
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}
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impl ApplicableDeclarationsCacheEntry {
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fn new(slice: &[DeclarationBlock]) -> ApplicableDeclarationsCacheEntry {
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let mut entry_declarations = Vec::new();
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for declarations in slice.iter() {
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entry_declarations.push(declarations.clone());
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}
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ApplicableDeclarationsCacheEntry {
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declarations: entry_declarations,
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}
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}
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}
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impl PartialEq for ApplicableDeclarationsCacheEntry {
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fn eq(&self, other: &ApplicableDeclarationsCacheEntry) -> bool {
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let this_as_query = ApplicableDeclarationsCacheQuery::new(self.declarations.as_slice());
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this_as_query.equiv(other)
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}
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}
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impl Hash for ApplicableDeclarationsCacheEntry {
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fn hash(&self, state: &mut sip::SipState) {
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let tmp = ApplicableDeclarationsCacheQuery::new(self.declarations.as_slice());
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tmp.hash(state);
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}
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}
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struct ApplicableDeclarationsCacheQuery<'a> {
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declarations: &'a [DeclarationBlock],
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}
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impl<'a> ApplicableDeclarationsCacheQuery<'a> {
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fn new(declarations: &'a [DeclarationBlock]) -> ApplicableDeclarationsCacheQuery<'a> {
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ApplicableDeclarationsCacheQuery {
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declarations: declarations,
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}
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}
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}
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// Workaround for lack of `ptr_eq` on Arcs...
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#[inline]
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fn arc_ptr_eq<T>(a: &Arc<T>, b: &Arc<T>) -> bool {
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unsafe {
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let a: uint = mem::transmute_copy(a);
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let b: uint = mem::transmute_copy(b);
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a == b
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}
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}
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impl<'a> Equiv<ApplicableDeclarationsCacheEntry> for ApplicableDeclarationsCacheQuery<'a> {
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fn equiv(&self, other: &ApplicableDeclarationsCacheEntry) -> bool {
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if self.declarations.len() != other.declarations.len() {
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return false
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}
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for (this, other) in self.declarations.iter().zip(other.declarations.iter()) {
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if !arc_ptr_eq(&this.declarations, &other.declarations) {
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return false
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}
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}
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return true
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}
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}
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impl<'a> Hash for ApplicableDeclarationsCacheQuery<'a> {
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fn hash(&self, state: &mut sip::SipState) {
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for declaration in self.declarations.iter() {
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let ptr: uint = unsafe {
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mem::transmute_copy(declaration)
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};
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ptr.hash(state);
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}
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}
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}
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static APPLICABLE_DECLARATIONS_CACHE_SIZE: uint = 32;
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pub struct ApplicableDeclarationsCache {
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cache: SimpleHashCache<ApplicableDeclarationsCacheEntry,Arc<ComputedValues>>,
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}
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impl ApplicableDeclarationsCache {
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pub fn new() -> ApplicableDeclarationsCache {
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ApplicableDeclarationsCache {
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cache: SimpleHashCache::new(APPLICABLE_DECLARATIONS_CACHE_SIZE),
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}
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}
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fn find(&self, declarations: &[DeclarationBlock]) -> Option<Arc<ComputedValues>> {
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match self.cache.find_equiv(&ApplicableDeclarationsCacheQuery::new(declarations)) {
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None => None,
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Some(ref values) => Some((*values).clone()),
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}
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}
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fn insert(&mut self, declarations: &[DeclarationBlock], style: Arc<ComputedValues>) {
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self.cache.insert(ApplicableDeclarationsCacheEntry::new(declarations), style)
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}
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}
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/// An LRU cache of the last few nodes seen, so that we can aggressively try to reuse their styles.
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pub struct StyleSharingCandidateCache {
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cache: LRUCache<StyleSharingCandidate,()>,
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}
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#[deriving(Clone)]
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pub struct StyleSharingCandidate {
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pub style: Arc<ComputedValues>,
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pub parent_style: Arc<ComputedValues>,
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pub local_name: Atom,
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pub class: Option<DOMString>,
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}
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impl PartialEq for StyleSharingCandidate {
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fn eq(&self, other: &StyleSharingCandidate) -> bool {
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arc_ptr_eq(&self.style, &other.style) &&
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arc_ptr_eq(&self.parent_style, &other.parent_style) &&
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self.local_name == other.local_name &&
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self.class == other.class
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}
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}
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impl StyleSharingCandidate {
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/// Attempts to create a style sharing candidate from this node. Returns
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/// the style sharing candidate or `None` if this node is ineligible for
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/// style sharing.
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fn new(node: &LayoutNode) -> Option<StyleSharingCandidate> {
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let parent_node = match node.parent_node() {
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None => return None,
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Some(parent_node) => parent_node,
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};
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if !parent_node.is_element() {
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return None
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}
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let style = unsafe {
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match *node.borrow_layout_data_unchecked() {
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None => return None,
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Some(ref layout_data_ref) => {
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match layout_data_ref.shared_data.style {
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None => return None,
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Some(ref data) => (*data).clone(),
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}
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}
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}
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};
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let parent_style = unsafe {
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match *parent_node.borrow_layout_data_unchecked() {
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None => return None,
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Some(ref parent_layout_data_ref) => {
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match parent_layout_data_ref.shared_data.style {
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None => return None,
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Some(ref data) => (*data).clone(),
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}
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}
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}
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};
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let mut style = Some(style);
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let mut parent_style = Some(parent_style);
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let element = node.as_element();
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if element.style_attribute().is_some() {
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return None
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}
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Some(StyleSharingCandidate {
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style: style.take_unwrap(),
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parent_style: parent_style.take_unwrap(),
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local_name: element.get_local_name().clone(),
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class: element.get_attr(&Null, "class")
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.map(|string| string.to_string()),
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})
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}
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fn can_share_style_with(&self, element: &LayoutElement) -> bool {
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if *element.get_local_name() != self.local_name {
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return false
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}
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match (&self.class, element.get_attr(&Null, "class")) {
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(&None, Some(_)) | (&Some(_), None) => return false,
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(&Some(ref this_class), Some(element_class)) if element_class != this_class.as_slice() => {
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return false
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}
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(&Some(_), Some(_)) | (&None, None) => {}
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}
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true
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}
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}
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static STYLE_SHARING_CANDIDATE_CACHE_SIZE: uint = 40;
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impl StyleSharingCandidateCache {
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pub fn new() -> StyleSharingCandidateCache {
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StyleSharingCandidateCache {
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cache: LRUCache::new(STYLE_SHARING_CANDIDATE_CACHE_SIZE),
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}
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}
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pub fn iter<'a>(&'a self) -> Items<'a,(StyleSharingCandidate,())> {
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self.cache.iter()
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}
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pub fn insert_if_possible(&mut self, node: &LayoutNode) {
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match StyleSharingCandidate::new(node) {
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None => {}
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Some(candidate) => self.cache.insert(candidate, ())
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}
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}
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pub fn touch(&mut self, index: uint) {
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self.cache.touch(index)
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}
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}
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/// The results of attempting to share a style.
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pub enum StyleSharingResult<'ln> {
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/// We didn't find anybody to share the style with. The boolean indicates whether the style
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/// is shareable at all.
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CannotShare(bool),
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/// The node's style can be shared. The integer specifies the index in the LRU cache that was
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/// hit.
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StyleWasShared(uint),
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}
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pub trait MatchMethods {
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/// Performs aux initialization, selector matching, cascading, and flow construction
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/// sequentially.
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fn recalc_style_for_subtree(&self,
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stylist: &Stylist,
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layout_context: &LayoutContext,
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applicable_declarations: &mut ApplicableDeclarations,
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parent: Option<LayoutNode>);
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fn match_node(&self,
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stylist: &Stylist,
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applicable_declarations: &mut ApplicableDeclarations,
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shareable: &mut bool);
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/// Attempts to share a style with another node. This method is unsafe because it depends on
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/// the `style_sharing_candidate_cache` having only live nodes in it, and we have no way to
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/// guarantee that at the type system level yet.
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unsafe fn share_style_if_possible(&self,
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style_sharing_candidate_cache:
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&mut StyleSharingCandidateCache,
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parent: Option<LayoutNode>)
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-> StyleSharingResult;
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unsafe fn cascade_node(&self,
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parent: Option<LayoutNode>,
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applicable_declarations: &ApplicableDeclarations,
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applicable_declarations_cache: &mut ApplicableDeclarationsCache);
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}
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trait PrivateMatchMethods {
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fn cascade_node_pseudo_element(&self,
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parent_style: Option<&Arc<ComputedValues>>,
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applicable_declarations: &[DeclarationBlock],
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style: &mut Option<Arc<ComputedValues>>,
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applicable_declarations_cache: &mut
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ApplicableDeclarationsCache,
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shareable: bool);
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fn share_style_with_candidate_if_possible(&self,
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parent_node: Option<LayoutNode>,
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candidate: &StyleSharingCandidate)
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-> Option<Arc<ComputedValues>>;
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}
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impl<'ln> PrivateMatchMethods for LayoutNode<'ln> {
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fn cascade_node_pseudo_element(&self,
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parent_style: Option<&Arc<ComputedValues>>,
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applicable_declarations: &[DeclarationBlock],
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style: &mut Option<Arc<ComputedValues>>,
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applicable_declarations_cache: &mut
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ApplicableDeclarationsCache,
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shareable: bool) {
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let this_style;
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let cacheable;
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match parent_style {
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Some(ref parent_style) => {
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let cache_entry = applicable_declarations_cache.find(applicable_declarations);
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let cached_computed_values = match cache_entry {
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None => None,
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Some(ref style) => Some(&**style),
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};
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let (the_style, is_cacheable) = cascade(applicable_declarations,
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shareable,
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Some(&***parent_style),
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cached_computed_values);
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cacheable = is_cacheable;
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this_style = Arc::new(the_style);
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}
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None => {
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let (the_style, is_cacheable) = cascade(applicable_declarations,
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shareable,
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None,
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None);
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cacheable = is_cacheable;
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this_style = Arc::new(the_style);
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}
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};
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// Cache the resolved style if it was cacheable.
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if cacheable {
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applicable_declarations_cache.insert(applicable_declarations, this_style.clone());
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}
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*style = Some(this_style);
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}
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fn share_style_with_candidate_if_possible(&self,
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parent_node: Option<LayoutNode>,
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candidate: &StyleSharingCandidate)
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-> Option<Arc<ComputedValues>> {
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assert!(self.is_element());
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let parent_node = match parent_node {
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Some(ref parent_node) if parent_node.is_element() => parent_node,
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Some(_) | None => return None,
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};
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let parent_layout_data: &Option<LayoutDataWrapper> = unsafe {
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mem::transmute(parent_node.borrow_layout_data_unchecked())
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};
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match parent_layout_data {
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&Some(ref parent_layout_data_ref) => {
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// Check parent style.
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let parent_style = parent_layout_data_ref.shared_data.style.as_ref().unwrap();
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if !arc_ptr_eq(parent_style, &candidate.parent_style) {
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return None
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}
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// Check tag names, classes, etc.
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if !candidate.can_share_style_with(&self.as_element()) {
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return None
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}
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return Some(candidate.style.clone())
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}
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_ => {}
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}
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None
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}
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}
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impl<'ln> MatchMethods for LayoutNode<'ln> {
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fn match_node(&self,
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stylist: &Stylist,
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applicable_declarations: &mut ApplicableDeclarations,
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shareable: &mut bool) {
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let style_attribute = self.as_element().style_attribute().as_ref();
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applicable_declarations.normal_shareable =
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stylist.push_applicable_declarations(self,
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style_attribute,
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None,
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&mut applicable_declarations.normal);
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stylist.push_applicable_declarations(self,
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None,
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Some(Before),
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&mut applicable_declarations.before);
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stylist.push_applicable_declarations(self,
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None,
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Some(After),
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&mut applicable_declarations.after);
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*shareable = applicable_declarations.normal_shareable
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}
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unsafe fn share_style_if_possible(&self,
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style_sharing_candidate_cache:
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&mut StyleSharingCandidateCache,
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parent: Option<LayoutNode>)
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-> StyleSharingResult {
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if !self.is_element() {
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return CannotShare(false)
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}
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let ok = {
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let element = self.as_element();
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element.style_attribute().is_none() && element.get_attr(&Null, "id").is_none()
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};
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if !ok {
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return CannotShare(false)
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}
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for (i, &(ref candidate, ())) in style_sharing_candidate_cache.iter().enumerate() {
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match self.share_style_with_candidate_if_possible(parent.clone(), candidate) {
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Some(shared_style) => {
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// Yay, cache hit. Share the style.
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let mut layout_data_ref = self.mutate_layout_data();
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layout_data_ref.get_mut_ref().shared_data.style = Some(shared_style);
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return StyleWasShared(i)
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}
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None => {}
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}
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}
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CannotShare(true)
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}
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fn recalc_style_for_subtree(&self,
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stylist: &Stylist,
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layout_context: &LayoutContext,
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applicable_declarations: &mut ApplicableDeclarations,
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parent: Option<LayoutNode>) {
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self.initialize_layout_data(layout_context.shared.layout_chan.clone());
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// First, check to see whether we can share a style with someone.
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let sharing_result = unsafe {
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self.share_style_if_possible(layout_context.style_sharing_candidate_cache(), parent.clone())
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};
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// Otherwise, match and cascade selectors.
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match sharing_result {
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CannotShare(mut shareable) => {
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if self.is_element() {
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self.match_node(stylist, applicable_declarations, &mut shareable)
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}
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unsafe {
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self.cascade_node(parent,
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applicable_declarations,
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layout_context.applicable_declarations_cache())
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}
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applicable_declarations.clear();
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// Add ourselves to the LRU cache.
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if shareable {
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layout_context.style_sharing_candidate_cache().insert_if_possible(self)
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}
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}
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StyleWasShared(index) => layout_context.style_sharing_candidate_cache().touch(index),
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}
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for kid in self.children() {
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kid.recalc_style_for_subtree(stylist,
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layout_context,
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applicable_declarations,
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Some(self.clone()))
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}
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// Construct flows.
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let layout_node = ThreadSafeLayoutNode::new(self);
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let mut flow_constructor = FlowConstructor::new(layout_context);
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flow_constructor.process(&layout_node);
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}
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unsafe fn cascade_node(&self,
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parent: Option<LayoutNode>,
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applicable_declarations: &ApplicableDeclarations,
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applicable_declarations_cache: &mut ApplicableDeclarationsCache) {
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// Get our parent's style. This must be unsafe so that we don't touch the parent's
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// borrow flags.
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//
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// FIXME(pcwalton): Isolate this unsafety into the `wrapper` module to allow
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// enforced safe, race-free access to the parent style.
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let parent_style = match parent {
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None => None,
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Some(parent_node) => {
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let parent_layout_data = parent_node.borrow_layout_data_unchecked();
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match *parent_layout_data {
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None => fail!("no parent data?!"),
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Some(ref parent_layout_data) => {
|
|
match parent_layout_data.shared_data.style {
|
|
None => fail!("parent hasn't been styled yet?!"),
|
|
Some(ref style) => Some(style),
|
|
}
|
|
}
|
|
}
|
|
}
|
|
};
|
|
|
|
let mut layout_data_ref = self.mutate_layout_data();
|
|
match &mut *layout_data_ref {
|
|
&None => fail!("no layout data"),
|
|
&Some(ref mut layout_data) => {
|
|
self.cascade_node_pseudo_element(parent_style,
|
|
applicable_declarations.normal.as_slice(),
|
|
&mut layout_data.shared_data.style,
|
|
applicable_declarations_cache,
|
|
applicable_declarations.normal_shareable);
|
|
if applicable_declarations.before.len() > 0 {
|
|
self.cascade_node_pseudo_element(Some(layout_data.shared_data.style.get_ref()),
|
|
applicable_declarations.before.as_slice(),
|
|
&mut layout_data.data.before_style,
|
|
applicable_declarations_cache,
|
|
false);
|
|
}
|
|
if applicable_declarations.after.len() > 0 {
|
|
self.cascade_node_pseudo_element(Some(layout_data.shared_data.style.get_ref()),
|
|
applicable_declarations.after.as_slice(),
|
|
&mut layout_data.data.after_style,
|
|
applicable_declarations_cache,
|
|
false);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|