mirror of
https://github.com/servo/servo.git
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a30da7ad8e
This lets us rely less on raw pointers, thus better tracking the lifetime of the rule node values while dropping strong references etc.
617 lines
24 KiB
Rust
617 lines
24 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 https://mozilla.org/MPL/2.0/. */
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#![deny(unsafe_code)]
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//! The rule tree.
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use crate::applicable_declarations::ApplicableDeclarationList;
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use crate::properties::{LonghandIdSet, PropertyDeclarationBlock};
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use crate::shared_lock::{Locked, StylesheetGuards};
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use servo_arc::{Arc, ArcBorrow};
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use smallvec::SmallVec;
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use std::io::{self, Write};
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mod core;
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mod level;
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mod map;
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mod source;
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mod unsafe_box;
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pub use self::core::{RuleTree, StrongRuleNode};
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pub use self::level::{CascadeLevel, ShadowCascadeOrder};
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pub use self::source::StyleSource;
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impl RuleTree {
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fn dump<W: Write>(&self, guards: &StylesheetGuards, writer: &mut W) {
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let _ = writeln!(writer, " + RuleTree");
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self.root().dump(guards, writer, 0);
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}
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/// Dump the rule tree to stdout.
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pub fn dump_stdout(&self, guards: &StylesheetGuards) {
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let mut stdout = io::stdout();
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self.dump(guards, &mut stdout);
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}
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/// Inserts the given rules, that must be in proper order by specifity, and
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/// returns the corresponding rule node representing the last inserted one.
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///
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/// !important rules are detected and inserted into the appropriate position
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/// in the rule tree. This allows selector matching to ignore importance,
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/// while still maintaining the appropriate cascade order in the rule tree.
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pub fn insert_ordered_rules_with_important<'a, I>(
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&self,
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iter: I,
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guards: &StylesheetGuards,
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) -> StrongRuleNode
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where
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I: Iterator<Item = (StyleSource, CascadeLevel)>,
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{
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use self::CascadeLevel::*;
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let mut current = self.root().clone();
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let mut found_important = false;
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let mut important_author = SmallVec::<[(StyleSource, ShadowCascadeOrder); 4]>::new();
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let mut important_user = SmallVec::<[StyleSource; 4]>::new();
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let mut important_ua = SmallVec::<[StyleSource; 4]>::new();
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let mut transition = None;
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for (source, level) in iter {
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debug_assert!(!level.is_important(), "Important levels handled internally");
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let any_important = {
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let pdb = source.read(level.guard(guards));
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pdb.any_important()
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};
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if any_important {
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found_important = true;
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match level {
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AuthorNormal {
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shadow_cascade_order,
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} => {
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important_author.push((source.clone(), shadow_cascade_order));
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},
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UANormal => important_ua.push(source.clone()),
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UserNormal => important_user.push(source.clone()),
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_ => {},
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};
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}
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// We don't optimize out empty rules, even though we could.
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//
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// Inspector relies on every rule being inserted in the normal level
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// at least once, in order to return the rules with the correct
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// specificity order.
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//
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// TODO(emilio): If we want to apply these optimizations without
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// breaking inspector's expectations, we'd need to run
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// selector-matching again at the inspector's request. That may or
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// may not be a better trade-off.
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if matches!(level, Transitions) && found_important {
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// There can be at most one transition, and it will come at
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// the end of the iterator. Stash it and apply it after
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// !important rules.
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debug_assert!(transition.is_none());
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transition = Some(source);
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} else {
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current = current.ensure_child(self.root(), source, level);
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}
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}
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// Early-return in the common case of no !important declarations.
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if !found_important {
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return current;
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}
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// Insert important declarations, in order of increasing importance,
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// followed by any transition rule.
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//
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// Inner shadow wins over same-tree, which wins over outer-shadow.
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//
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// We negate the shadow cascade order to preserve the right PartialOrd
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// behavior.
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if !important_author.is_empty() &&
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important_author.first().unwrap().1 != important_author.last().unwrap().1
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{
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// We only need to sort if the important rules come from
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// different trees, but we need this sort to be stable.
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//
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// FIXME(emilio): This could maybe be smarter, probably by chunking
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// the important rules while inserting, and iterating the outer
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// chunks in reverse order.
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//
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// That is, if we have rules with levels like: -1 -1 -1 0 0 0 1 1 1,
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// we're really only sorting the chunks, while keeping elements
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// inside the same chunk already sorted. Seems like we could try to
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// keep a SmallVec-of-SmallVecs with the chunks and just iterate the
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// outer in reverse.
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important_author.sort_by_key(|&(_, order)| -order);
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}
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for (source, shadow_cascade_order) in important_author.drain(..) {
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current = current.ensure_child(
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self.root(),
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source,
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AuthorImportant {
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shadow_cascade_order: -shadow_cascade_order,
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},
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);
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}
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for source in important_user.drain(..) {
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current = current.ensure_child(self.root(), source, UserImportant);
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}
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for source in important_ua.drain(..) {
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current = current.ensure_child(self.root(), source, UAImportant);
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}
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if let Some(source) = transition {
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current = current.ensure_child(self.root(), source, Transitions);
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}
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current
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}
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/// Given a list of applicable declarations, insert the rules and return the
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/// corresponding rule node.
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pub fn compute_rule_node(
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&self,
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applicable_declarations: &mut ApplicableDeclarationList,
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guards: &StylesheetGuards,
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) -> StrongRuleNode {
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self.insert_ordered_rules_with_important(
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applicable_declarations.drain(..).map(|d| d.for_rule_tree()),
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guards,
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)
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}
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/// Insert the given rules, that must be in proper order by specifity, and
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/// return the corresponding rule node representing the last inserted one.
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pub fn insert_ordered_rules<'a, I>(&self, iter: I) -> StrongRuleNode
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where
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I: Iterator<Item = (StyleSource, CascadeLevel)>,
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{
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self.insert_ordered_rules_from(self.root().clone(), iter)
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}
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fn insert_ordered_rules_from<'a, I>(&self, from: StrongRuleNode, iter: I) -> StrongRuleNode
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where
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I: Iterator<Item = (StyleSource, CascadeLevel)>,
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{
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let mut current = from;
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for (source, level) in iter {
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current = current.ensure_child(self.root(), source, level);
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}
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current
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}
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/// Replaces a rule in a given level (if present) for another rule.
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///
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/// Returns the resulting node that represents the new path, or None if
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/// the old path is still valid.
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pub fn update_rule_at_level(
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&self,
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level: CascadeLevel,
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pdb: Option<ArcBorrow<Locked<PropertyDeclarationBlock>>>,
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path: &StrongRuleNode,
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guards: &StylesheetGuards,
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important_rules_changed: &mut bool,
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) -> Option<StrongRuleNode> {
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// TODO(emilio): Being smarter with lifetimes we could avoid a bit of
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// the refcount churn.
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let mut current = path.clone();
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*important_rules_changed = false;
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// First walk up until the first less-or-equally specific rule.
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let mut children = SmallVec::<[_; 10]>::new();
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while current.cascade_level() > level {
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children.push((
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current.style_source().unwrap().clone(),
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current.cascade_level(),
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));
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current = current.parent().unwrap().clone();
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}
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// Then remove the one at the level we want to replace, if any.
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//
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// NOTE: Here we assume that only one rule can be at the level we're
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// replacing.
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//
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// This is certainly true for HTML style attribute rules, animations and
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// transitions, but could not be so for SMIL animations, which we'd need
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// to special-case (isn't hard, it's just about removing the `if` and
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// special cases, and replacing them for a `while` loop, avoiding the
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// optimizations).
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if current.cascade_level() == level {
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*important_rules_changed |= level.is_important();
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let current_decls = current.style_source().unwrap().as_declarations();
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// If the only rule at the level we're replacing is exactly the
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// same as `pdb`, we're done, and `path` is still valid.
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if let (Some(ref pdb), Some(ref current_decls)) = (pdb, current_decls) {
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// If the only rule at the level we're replacing is exactly the
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// same as `pdb`, we're done, and `path` is still valid.
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//
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// TODO(emilio): Another potential optimization is the one where
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// we can just replace the rule at that level for `pdb`, and
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// then we don't need to re-create the children, and `path` is
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// also equally valid. This is less likely, and would require an
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// in-place mutation of the source, which is, at best, fiddly,
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// so let's skip it for now.
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let is_here_already = ArcBorrow::ptr_eq(pdb, current_decls);
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if is_here_already {
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debug!("Picking the fast path in rule replacement");
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return None;
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}
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}
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if current_decls.is_some() {
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current = current.parent().unwrap().clone();
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}
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}
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// Insert the rule if it's relevant at this level in the cascade.
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//
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// These optimizations are likely to be important, because the levels
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// where replacements apply (style and animations) tend to trigger
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// pretty bad styling cases already.
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if let Some(pdb) = pdb {
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if level.is_important() {
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if pdb.read_with(level.guard(guards)).any_important() {
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current = current.ensure_child(
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self.root(),
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StyleSource::from_declarations(pdb.clone_arc()),
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level,
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);
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*important_rules_changed = true;
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}
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} else {
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if pdb.read_with(level.guard(guards)).any_normal() {
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current = current.ensure_child(
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self.root(),
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StyleSource::from_declarations(pdb.clone_arc()),
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level,
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);
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}
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}
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}
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// Now the rule is in the relevant place, push the children as
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// necessary.
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let rule = self.insert_ordered_rules_from(current, children.drain(..).rev());
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Some(rule)
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}
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/// Returns new rule nodes without Transitions level rule.
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pub fn remove_transition_rule_if_applicable(&self, path: &StrongRuleNode) -> StrongRuleNode {
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// Return a clone if there is no transition level.
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if path.cascade_level() != CascadeLevel::Transitions {
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return path.clone();
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}
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path.parent().unwrap().clone()
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}
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/// Returns new rule node without rules from declarative animations.
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pub fn remove_animation_rules(&self, path: &StrongRuleNode) -> StrongRuleNode {
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// Return a clone if there are no animation rules.
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if !path.has_animation_or_transition_rules() {
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return path.clone();
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}
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let iter = path
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.self_and_ancestors()
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.take_while(|node| node.cascade_level() >= CascadeLevel::SMILOverride);
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let mut last = path;
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let mut children = SmallVec::<[_; 10]>::new();
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for node in iter {
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if !node.cascade_level().is_animation() {
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children.push((node.style_source().unwrap().clone(), node.cascade_level()));
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}
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last = node;
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}
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let rule = self
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.insert_ordered_rules_from(last.parent().unwrap().clone(), children.drain(..).rev());
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rule
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}
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/// Returns new rule node by adding animation rules at transition level.
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/// The additional rules must be appropriate for the transition
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/// level of the cascade, which is the highest level of the cascade.
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/// (This is the case for one current caller, the cover rule used
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/// for CSS transitions.)
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pub fn add_animation_rules_at_transition_level(
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&self,
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path: &StrongRuleNode,
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pdb: Arc<Locked<PropertyDeclarationBlock>>,
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guards: &StylesheetGuards,
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) -> StrongRuleNode {
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let mut dummy = false;
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self.update_rule_at_level(
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CascadeLevel::Transitions,
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Some(pdb.borrow_arc()),
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path,
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guards,
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&mut dummy,
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)
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.expect("Should return a valid rule node")
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}
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}
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impl StrongRuleNode {
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/// Get an iterator for this rule node and its ancestors.
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pub fn self_and_ancestors(&self) -> SelfAndAncestors {
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SelfAndAncestors {
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current: Some(self),
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}
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}
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/// Returns true if any properties specified by `rule_type_mask` was set by
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/// an author rule.
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#[cfg(feature = "gecko")]
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pub fn has_author_specified_rules<E>(
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&self,
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mut element: E,
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mut pseudo: Option<PseudoElement>,
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guards: &StylesheetGuards,
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rule_type_mask: u32,
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author_colors_allowed: bool,
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) -> bool
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where
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E: crate::dom::TElement,
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{
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use crate::gecko_bindings::structs::NS_AUTHOR_SPECIFIED_BACKGROUND;
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use crate::gecko_bindings::structs::NS_AUTHOR_SPECIFIED_BORDER;
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use crate::gecko_bindings::structs::NS_AUTHOR_SPECIFIED_PADDING;
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use crate::properties::{CSSWideKeyword, LonghandId};
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use crate::properties::{PropertyDeclaration, PropertyDeclarationId};
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use std::borrow::Cow;
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// Reset properties:
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const BACKGROUND_PROPS: &'static [LonghandId] =
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&[LonghandId::BackgroundColor, LonghandId::BackgroundImage];
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const BORDER_PROPS: &'static [LonghandId] = &[
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LonghandId::BorderTopColor,
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LonghandId::BorderTopStyle,
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LonghandId::BorderTopWidth,
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LonghandId::BorderRightColor,
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LonghandId::BorderRightStyle,
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LonghandId::BorderRightWidth,
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LonghandId::BorderBottomColor,
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LonghandId::BorderBottomStyle,
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LonghandId::BorderBottomWidth,
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LonghandId::BorderLeftColor,
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LonghandId::BorderLeftStyle,
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LonghandId::BorderLeftWidth,
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LonghandId::BorderTopLeftRadius,
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LonghandId::BorderTopRightRadius,
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LonghandId::BorderBottomRightRadius,
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LonghandId::BorderBottomLeftRadius,
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LonghandId::BorderInlineStartColor,
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LonghandId::BorderInlineStartStyle,
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LonghandId::BorderInlineStartWidth,
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LonghandId::BorderInlineEndColor,
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LonghandId::BorderInlineEndStyle,
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LonghandId::BorderInlineEndWidth,
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LonghandId::BorderBlockStartColor,
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LonghandId::BorderBlockStartStyle,
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LonghandId::BorderBlockStartWidth,
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LonghandId::BorderBlockEndColor,
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LonghandId::BorderBlockEndStyle,
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LonghandId::BorderBlockEndWidth,
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];
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const PADDING_PROPS: &'static [LonghandId] = &[
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LonghandId::PaddingTop,
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LonghandId::PaddingRight,
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LonghandId::PaddingBottom,
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LonghandId::PaddingLeft,
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LonghandId::PaddingInlineStart,
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LonghandId::PaddingInlineEnd,
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LonghandId::PaddingBlockStart,
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LonghandId::PaddingBlockEnd,
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];
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// Set of properties that we are currently interested in.
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let mut properties = LonghandIdSet::new();
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if rule_type_mask & NS_AUTHOR_SPECIFIED_BACKGROUND != 0 {
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for id in BACKGROUND_PROPS {
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properties.insert(*id);
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}
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}
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if rule_type_mask & NS_AUTHOR_SPECIFIED_BORDER != 0 {
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for id in BORDER_PROPS {
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properties.insert(*id);
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}
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}
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if rule_type_mask & NS_AUTHOR_SPECIFIED_PADDING != 0 {
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for id in PADDING_PROPS {
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properties.insert(*id);
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}
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}
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// If author colors are not allowed, don't look at those properties
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// (except for background-color which is special and we handle below).
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if !author_colors_allowed {
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properties.remove_all(LonghandIdSet::ignored_when_colors_disabled());
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if rule_type_mask & NS_AUTHOR_SPECIFIED_BACKGROUND != 0 {
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properties.insert(LonghandId::BackgroundColor);
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}
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}
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let mut element_rule_node = Cow::Borrowed(self);
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loop {
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// We need to be careful not to count styles covered up by
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// user-important or UA-important declarations. But we do want to
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// catch explicit inherit styling in those and check our parent
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// element to see whether we have user styling for those properties.
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// Note that we don't care here about inheritance due to lack of a
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// specified value, since all the properties we care about are reset
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// properties.
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let mut inherited_properties = LonghandIdSet::new();
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let mut have_explicit_ua_inherit = false;
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for node in element_rule_node.self_and_ancestors() {
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let source = node.style_source();
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let declarations = if source.is_some() {
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source
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.as_ref()
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.unwrap()
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.read(node.cascade_level().guard(guards))
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.declaration_importance_iter()
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} else {
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continue;
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};
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// Iterate over declarations of the longhands we care about.
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let node_importance = node.importance();
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let longhands = declarations.rev().filter_map(|(declaration, importance)| {
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if importance != node_importance {
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return None;
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}
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match declaration.id() {
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PropertyDeclarationId::Longhand(id) => Some((id, declaration)),
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_ => None,
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}
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});
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let is_author = node.cascade_level().origin() == Origin::Author;
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for (id, declaration) in longhands {
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if !properties.contains(id) {
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continue;
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}
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if is_author {
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if !author_colors_allowed {
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if let PropertyDeclaration::BackgroundColor(ref color) = *declaration {
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if color.is_transparent() {
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return true;
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}
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continue;
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}
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}
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return true;
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}
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// This property was set by a non-author rule.
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// Stop looking for it in this element's rule
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// nodes.
|
|
properties.remove(id);
|
|
|
|
// However, if it is inherited, then it might be
|
|
// inherited from an author rule from an
|
|
// ancestor element's rule nodes.
|
|
if declaration.get_css_wide_keyword() == Some(CSSWideKeyword::Inherit) {
|
|
have_explicit_ua_inherit = true;
|
|
inherited_properties.insert(id);
|
|
}
|
|
}
|
|
}
|
|
|
|
if !have_explicit_ua_inherit {
|
|
break;
|
|
}
|
|
|
|
// Continue to the parent element and search for the inherited properties.
|
|
if let Some(pseudo) = pseudo.take() {
|
|
if pseudo.inherits_from_default_values() {
|
|
break;
|
|
}
|
|
} else {
|
|
element = match element.inheritance_parent() {
|
|
Some(parent) => parent,
|
|
None => break,
|
|
};
|
|
|
|
let parent_data = element.mutate_data().unwrap();
|
|
let parent_rule_node = parent_data.styles.primary().rules().clone();
|
|
element_rule_node = Cow::Owned(parent_rule_node);
|
|
}
|
|
|
|
properties = inherited_properties;
|
|
}
|
|
|
|
false
|
|
}
|
|
|
|
/// Returns true if there is either animation or transition level rule.
|
|
pub fn has_animation_or_transition_rules(&self) -> bool {
|
|
self.self_and_ancestors()
|
|
.take_while(|node| node.cascade_level() >= CascadeLevel::SMILOverride)
|
|
.any(|node| node.cascade_level().is_animation())
|
|
}
|
|
|
|
/// Get a set of properties whose CascadeLevel are higher than Animations
|
|
/// but not equal to Transitions.
|
|
///
|
|
/// If there are any custom properties, we set the boolean value of the
|
|
/// returned tuple to true.
|
|
pub fn get_properties_overriding_animations(
|
|
&self,
|
|
guards: &StylesheetGuards,
|
|
) -> (LonghandIdSet, bool) {
|
|
use crate::properties::PropertyDeclarationId;
|
|
|
|
// We want to iterate over cascade levels that override the animations
|
|
// level, i.e. !important levels and the transitions level.
|
|
//
|
|
// However, we actually want to skip the transitions level because
|
|
// although it is higher in the cascade than animations, when both
|
|
// transitions and animations are present for a given element and
|
|
// property, transitions are suppressed so that they don't actually
|
|
// override animations.
|
|
let iter = self
|
|
.self_and_ancestors()
|
|
.skip_while(|node| node.cascade_level() == CascadeLevel::Transitions)
|
|
.take_while(|node| node.cascade_level() > CascadeLevel::Animations);
|
|
let mut result = (LonghandIdSet::new(), false);
|
|
for node in iter {
|
|
let style = node.style_source().unwrap();
|
|
for (decl, important) in style
|
|
.read(node.cascade_level().guard(guards))
|
|
.declaration_importance_iter()
|
|
{
|
|
// Although we are only iterating over cascade levels that
|
|
// override animations, in a given property declaration block we
|
|
// can have a mixture of !important and non-!important
|
|
// declarations but only the !important declarations actually
|
|
// override animations.
|
|
if important.important() {
|
|
match decl.id() {
|
|
PropertyDeclarationId::Longhand(id) => result.0.insert(id),
|
|
PropertyDeclarationId::Custom(_) => result.1 = true,
|
|
}
|
|
}
|
|
}
|
|
}
|
|
result
|
|
}
|
|
}
|
|
|
|
/// An iterator over a rule node and its ancestors.
|
|
#[derive(Clone)]
|
|
pub struct SelfAndAncestors<'a> {
|
|
current: Option<&'a StrongRuleNode>,
|
|
}
|
|
|
|
impl<'a> Iterator for SelfAndAncestors<'a> {
|
|
type Item = &'a StrongRuleNode;
|
|
|
|
fn next(&mut self) -> Option<Self::Item> {
|
|
self.current.map(|node| {
|
|
self.current = node.parent();
|
|
node
|
|
})
|
|
}
|
|
}
|