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Auto merge of #16909 - emilio:simplify-cascade, r=bholley

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style: Refactor the cascade function.

The `cascade_primary_or_pseudo` function was nice when we shared more code, but
right now I think it just makes it harder to understand what's going on.

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This commit is contained in:
bors-servo 2017-05-17 11:19:56 -05:00 • committed by GitHub
commit c6c960a661
6 changed files with 72 additions and 94 deletions
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146
components/style/matching.rs
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@ -496,6 +496,27 @@ trait PrivateMatchMethods: TElement {
primary_style: &ComputedStyle,
eager_pseudo_style: Option<&ComputedStyle>)
-> Arc<ComputedValues> {
if let Some(pseudo) = self.implemented_pseudo_element() {
debug_assert!(eager_pseudo_style.is_none());
// This is an element-backed pseudo, just grab the styles from the
// parent if it's eager, and recascade otherwise.
//
// We also recascade if the eager pseudo-style has any animation
// rules, because we don't cascade those during the eager traversal.
//
// We could make that a bit better if the complexity cost is not too
// big, but given further restyles are posted directly to
// pseudo-elements, it doesn't seem worth the effort at a glance.
if pseudo.is_eager() && self.get_animation_rules().is_empty() {
let parent = self.parent_element().unwrap();
let parent_data = parent.borrow_data().unwrap();
let pseudo_style =
parent_data.styles().pseudos.get(&pseudo).unwrap();
return pseudo_style.values().clone()
}
}
// Grab the rule node.
let rule_node = &eager_pseudo_style.unwrap_or(primary_style).rules;
let inherit_mode = if eager_pseudo_style.is_some() {
@ -513,97 +534,66 @@ trait PrivateMatchMethods: TElement {
/// Computes values and damage for the primary or pseudo style of an element,
/// setting them on the ElementData.
fn cascade_primary_or_pseudo(&self,
context: &mut StyleContext<Self>,
data: &mut ElementData,
pseudo: Option<&PseudoElement>) {
debug_assert!(pseudo.is_none() || self.implemented_pseudo_element().is_none(),
"Pseudo-element-implementing elements can't have pseudos!");
fn cascade_primary(&self,
context: &mut StyleContext<Self>,
data: &mut ElementData) {
// Collect some values.
let (mut styles, restyle) = data.styles_and_restyle_mut();
let mut primary_style = &mut styles.primary;
let pseudos = &mut styles.pseudos;
let mut pseudo_style = match pseudo {
Some(p) => {
let style = pseudos.get_mut(p);
debug_assert!(style.is_some());
style
}
None => None,
};
let mut old_values = match pseudo_style {
Some(ref mut s) => s.values.take(),
None => primary_style.values.take(),
};
let mut old_values = primary_style.values.take();
// Compute the new values.
let mut new_values = match self.implemented_pseudo_element() {
Some(ref pseudo) => {
// This is an element-backed pseudo, just grab the styles from
// the parent if it's eager, and recascade otherwise.
//
// We also recascade if the eager pseudo-style has any animation
// rules, because we don't cascade those during the eager
// traversal. We could make that a bit better if the complexity
// cost is not too big, but given further restyles are posted
// directly to pseudo-elements, it doesn't seem worth the effort
// at a glance.
if pseudo.is_eager() &&
self.get_animation_rules().is_empty() {
let parent = self.parent_element().unwrap();
let parent_data = parent.borrow_data().unwrap();
let pseudo_style =
parent_data.styles().pseudos.get(pseudo).unwrap();
pseudo_style.values().clone()
} else {
self.cascade_internal(context,
primary_style,
None)
}
}
None => {
// Else it's an eager pseudo or a normal element, do the cascade
// work.
self.cascade_internal(context,
primary_style,
pseudo_style.as_ref().map(|s| &**s))
}
};
let mut new_values = self.cascade_internal(context, primary_style, None);
// NB: Animations for pseudo-elements in Gecko are handled while
// traversing the pseudo-elements themselves.
if pseudo.is_none() &&
!context.shared.traversal_flags.for_animation_only() {
if !context.shared.traversal_flags.for_animation_only() {
self.process_animations(context,
&mut old_values,
&mut new_values,
primary_style);
}
// Accumulate restyle damage.
if let Some(old) = old_values {
self.accumulate_damage(&context.shared,
restyle.unwrap(),
&old,
&new_values,
None);
}
// Set the new computed values.
primary_style.values = Some(new_values);
}
fn cascade_eager_pseudo(&self,
context: &mut StyleContext<Self>,
data: &mut ElementData,
pseudo: &PseudoElement) {
debug_assert!(pseudo.is_eager());
let (mut styles, restyle) = data.styles_and_restyle_mut();
let mut pseudo_style = styles.pseudos.get_mut(pseudo).unwrap();
let old_values = pseudo_style.values.take();
let new_values =
self.cascade_internal(context, &styles.primary, Some(pseudo_style));
if let Some(old) = old_values {
// ::before and ::after are element-backed in Gecko, so they do
// the damage calculation for themselves.
//
// FIXME(emilio): We have more element-backed stuff, and this is
// redundant for them right now.
if cfg!(feature = "servo") ||
pseudo.map_or(true, |p| !p.is_before_or_after()) {
if cfg!(feature = "servo") || !pseudo.is_before_or_after() {
self.accumulate_damage(&context.shared,
restyle.unwrap(),
&old,
&new_values,
pseudo);
Some(pseudo));
}
}
// Set the new computed values.
let mut relevant_style = pseudo_style.unwrap_or(primary_style);
relevant_style.values = Some(new_values);
pseudo_style.values = Some(new_values)
}
/// get_after_change_style removes the transition rules from the ComputedValues.
/// If there is no transition rule in the ComputedValues, it returns None.
#[cfg(feature = "gecko")]
@ -753,15 +743,11 @@ trait PrivateMatchMethods: TElement {
}
/// Computes and applies non-redundant damage.
///
/// FIXME(emilio): Damage for non-::before and non-::after element-backed
/// pseudo-elements should be refactored to go on themselves (right now they
/// do, but we apply this twice).
#[cfg(feature = "gecko")]
fn accumulate_damage(&self,
shared_context: &SharedStyleContext,
restyle: &mut RestyleData,
old_values: &Arc<ComputedValues>,
old_values: &ComputedValues,
new_values: &Arc<ComputedValues>,
pseudo: Option<&PseudoElement>) {
// Don't accumulate damage if we're in a restyle for reconstruction.
@ -797,12 +783,12 @@ trait PrivateMatchMethods: TElement {
fn accumulate_damage(&self,
_shared_context: &SharedStyleContext,
restyle: &mut RestyleData,
old_values: &Arc<ComputedValues>,
old_values: &ComputedValues,
new_values: &Arc<ComputedValues>,
pseudo: Option<&PseudoElement>) {
if restyle.damage != RestyleDamage::rebuild_and_reflow() {
let d = self.compute_restyle_damage(&old_values, &new_values, pseudo);
restyle.damage |= d;
restyle.damage |=
self.compute_restyle_damage(&old_values, &new_values, pseudo);
}
}
@ -1394,7 +1380,7 @@ pub trait MatchMethods : TElement {
/// 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_values: &Arc<ComputedValues>,
old_values: &ComputedValues,
new_values: &Arc<ComputedValues>,
pseudo: Option<&PseudoElement>)
-> RestyleDamage
@ -1418,15 +1404,7 @@ pub trait MatchMethods : TElement {
}
}
/// Performs the cascade for the element's primary style.
fn cascade_primary(&self,
context: &mut StyleContext<Self>,
mut data: &mut ElementData)
{
self.cascade_primary_or_pseudo(context, &mut data, None);
}
/// Performs the cascade for the element's eager pseudos.
/// Cascade the eager pseudo-elements of this element.
fn cascade_pseudos(&self,
context: &mut StyleContext<Self>,
mut data: &mut ElementData)
@ -1438,7 +1416,7 @@ pub trait MatchMethods : TElement {
// let us pass the mutable |data| to the cascade function.
let matched_pseudos = data.styles().pseudos.keys();
for pseudo in matched_pseudos {
self.cascade_primary_or_pseudo(context, data, Some(&pseudo));
self.cascade_eager_pseudo(context, data, &pseudo);
}
}