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style: [css-nesting] Parse parent selector

Browse source 
This parses the ampersand as a parent selector behind an
(off-by-default) selectors feature.

The plan is to call replace_parent_selector while we're doing the
CascadeData rebuilds, which is where we can have all the ancestor
nesting information.

No behavior change.

Differential Revision: https://phabricator.services.mozilla.com/D167237
This commit is contained in:
Emilio Cobos Álvarez 2023-01-24 10:02:18 +00:00 • committed by Martin Robinson
parent b024f5b2e7
commit 29c6094c80
5 changed files with 345 additions and 76 deletions
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1
components/malloc_size_of/lib.rs
View file

@ -715,6 +715,7 @@ where
Component::Root |
Component::Empty |
Component::Scope |
Component::ParentSelector |
Component::Nth(..) |
Component::Host(None) => 0,
}

111
components/selectors/builder.rs
View file

@ -96,31 +96,16 @@ impl<Impl: SelectorImpl> SelectorBuilder<Impl> {
/// Consumes the builder, producing a Selector.
#[inline(always)]
pub fn build(
&mut self,
parsed_pseudo: bool,
parsed_slotted: bool,
parsed_part: bool,
) -> ThinArc<SpecificityAndFlags, Component<Impl>> {
pub fn build(&mut self) -> ThinArc<SpecificityAndFlags, Component<Impl>> {
// Compute the specificity and flags.
let specificity = specificity(self.simple_selectors.iter());
let mut flags = SelectorFlags::empty();
if parsed_pseudo {
flags |= SelectorFlags::HAS_PSEUDO;
}
if parsed_slotted {
flags |= SelectorFlags::HAS_SLOTTED;
}
if parsed_part {
flags |= SelectorFlags::HAS_PART;
}
self.build_with_specificity_and_flags(SpecificityAndFlags { specificity, flags })
let sf = specificity_and_flags(self.simple_selectors.iter());
self.build_with_specificity_and_flags(sf)
}
/// Builds with an explicit SpecificityAndFlags. This is separated from build() so
/// that unit tests can pass an explicit specificity.
#[inline(always)]
pub fn build_with_specificity_and_flags(
pub(crate) fn build_with_specificity_and_flags(
&mut self,
spec: SpecificityAndFlags,
) -> ThinArc<SpecificityAndFlags, Component<Impl>> {
@ -203,6 +188,7 @@ bitflags! {
const HAS_PSEUDO = 1 << 0;
const HAS_SLOTTED = 1 << 1;
const HAS_PART = 1 << 2;
const HAS_PARENT = 1 << 3;
}
}
@ -227,6 +213,11 @@ impl SpecificityAndFlags {
self.flags.intersects(SelectorFlags::HAS_PSEUDO)
}
#[inline]
pub fn has_parent_selector(&self) -> bool {
self.flags.intersects(SelectorFlags::HAS_PARENT)
}
#[inline]
pub fn is_slotted(&self) -> bool {
self.flags.intersects(SelectorFlags::HAS_SLOTTED)
@ -241,7 +232,7 @@ impl SpecificityAndFlags {
const MAX_10BIT: u32 = (1u32 << 10) - 1;
#[derive(Add, AddAssign, Clone, Copy, Default, Eq, Ord, PartialEq, PartialOrd)]
struct Specificity {
pub(crate) struct Specificity {
id_selectors: u32,
class_like_selectors: u32,
element_selectors: u32,
@ -268,31 +259,40 @@ impl From<Specificity> for u32 {
}
}
fn specificity<Impl>(iter: slice::Iter<Component<Impl>>) -> u32
pub(crate) fn specificity_and_flags<Impl>(iter: slice::Iter<Component<Impl>>) -> SpecificityAndFlags
where
Impl: SelectorImpl,
{
complex_selector_specificity(iter).into()
complex_selector_specificity_and_flags(iter).into()
}
fn complex_selector_specificity<Impl>(iter: slice::Iter<Component<Impl>>) -> Specificity
fn complex_selector_specificity_and_flags<Impl>(
iter: slice::Iter<Component<Impl>>,
) -> SpecificityAndFlags
where
Impl: SelectorImpl,
{
fn simple_selector_specificity<Impl>(
fn component_specificity<Impl>(
simple_selector: &Component<Impl>,
specificity: &mut Specificity,
flags: &mut SelectorFlags,
) where
Impl: SelectorImpl,
{
match *simple_selector {
Component::Combinator(..) => {
unreachable!("Found combinator in simple selectors vector?");
},
Component::Part(..) | Component::PseudoElement(..) | Component::LocalName(..) => {
Component::Combinator(..) => {},
Component::ParentSelector => flags.insert(SelectorFlags::HAS_PARENT),
Component::Part(..) => {
flags.insert(SelectorFlags::HAS_PART);
specificity.element_selectors += 1
},
Component::PseudoElement(..) => {
flags.insert(SelectorFlags::HAS_PSEUDO);
specificity.element_selectors += 1
},
Component::LocalName(..) => specificity.element_selectors += 1,
Component::Slotted(ref selector) => {
flags.insert(SelectorFlags::HAS_SLOTTED);
specificity.element_selectors += 1;
// Note that due to the way ::slotted works we only compete with
// other ::slotted rules, so the above rule doesn't really
@ -301,12 +301,18 @@ where
//
// See: https://github.com/w3c/csswg-drafts/issues/1915
*specificity += Specificity::from(selector.specificity());
if selector.has_parent_selector() {
flags.insert(SelectorFlags::HAS_PARENT);
}
},
Component::Host(ref selector) => {
specificity.class_like_selectors += 1;
if let Some(ref selector) = *selector {
// See: https://github.com/w3c/csswg-drafts/issues/1915
*specificity += Specificity::from(selector.specificity());
if selector.has_parent_selector() {
flags.insert(SelectorFlags::HAS_PARENT);
}
}
},
Component::ID(..) => {
@ -331,17 +337,25 @@ where
// specificity of a regular pseudo-class with that of its
// selector argument S.
specificity.class_like_selectors += 1;
*specificity += max_selector_list_specificity(nth_of_data.selectors());
let sf = selector_list_specificity_and_flags(nth_of_data.selectors());
*specificity += Specificity::from(sf.specificity);
flags.insert(sf.flags);
},
Component::Negation(ref list) | Component::Is(ref list) | Component::Has(ref list) => {
Component::Where(ref list) |
Component::Negation(ref list) |
Component::Is(ref list) |
Component::Has(ref list) => {
// https://drafts.csswg.org/selectors/#specificity-rules:
//
// The specificity of an :is(), :not(), or :has() pseudo-class
// is replaced by the specificity of the most specific complex
// selector in its selector list argument.
*specificity += max_selector_list_specificity(list);
let sf = selector_list_specificity_and_flags(list);
if !matches!(*simple_selector, Component::Where(..)) {
*specificity += Specificity::from(sf.specificity);
}
flags.insert(sf.flags);
},
Component::Where(..) |
Component::ExplicitUniversalType |
Component::ExplicitAnyNamespace |
Component::ExplicitNoNamespace |
@ -352,19 +366,28 @@ where
}
}
/// Finds the maximum specificity of elements in the list and returns it.
fn max_selector_list_specificity<Impl: SelectorImpl>(list: &[Selector<Impl>]) -> Specificity {
let max = list
.iter()
.map(|selector| selector.specificity())
.max()
.unwrap_or(0);
Specificity::from(max)
}
let mut specificity = Default::default();
let mut flags = Default::default();
for simple_selector in iter {
simple_selector_specificity(&simple_selector, &mut specificity);
component_specificity(&simple_selector, &mut specificity, &mut flags);
}
SpecificityAndFlags {
specificity: specificity.into(),
flags,
}
specificity
}
/// Finds the maximum specificity of elements in the list and returns it.
pub(crate) fn selector_list_specificity_and_flags<Impl: SelectorImpl>(
list: &[Selector<Impl>],
) -> SpecificityAndFlags {
let mut specificity = 0;
let mut flags = SelectorFlags::empty();
for selector in list.iter() {
specificity = std::cmp::max(specificity, selector.specificity());
if selector.has_parent_selector() {
flags.insert(SelectorFlags::HAS_PARENT);
}
}
SpecificityAndFlags { specificity, flags }
}

3
components/selectors/matching.rs
View file

@ -811,6 +811,9 @@ where
.nest(|context| matches_complex_selector(selector.iter(), element, context))
})
},
// These should only work at parse time, should be replaced with :is() at CascadeData build
// time.
Component::ParentSelector => false,
Component::Scope => match context.shared.scope_element {
Some(ref scope_element) => element.opaque() == *scope_element,
None => element.is_root(),

280
components/selectors/parser.rs
View file

@ -6,7 +6,10 @@ use crate::attr::{AttrSelectorOperator, AttrSelectorWithOptionalNamespace};
use crate::attr::{NamespaceConstraint, ParsedAttrSelectorOperation};
use crate::attr::{ParsedCaseSensitivity, SELECTOR_WHITESPACE};
use crate::bloom::BLOOM_HASH_MASK;
use crate::builder::{SelectorBuilder, SelectorFlags, SpecificityAndFlags};
use crate::builder::{
selector_list_specificity_and_flags, SelectorBuilder, SelectorFlags, Specificity,
SpecificityAndFlags,
};
use crate::context::QuirksMode;
use crate::sink::Push;
pub use crate::visitor::SelectorVisitor;
@ -16,7 +19,7 @@ use cssparser::{BasicParseError, BasicParseErrorKind, ParseError, ParseErrorKind
use cssparser::{CowRcStr, Delimiter, SourceLocation};
use cssparser::{Parser as CssParser, ToCss, Token};
use precomputed_hash::PrecomputedHash;
use servo_arc::ThinArc;
use servo_arc::{HeaderWithLength, ThinArc, UniqueArc};
use size_of_test::size_of_test;
use smallvec::SmallVec;
use std::borrow::{Borrow, Cow};
@ -271,6 +274,11 @@ pub trait Parser<'i> {
false
}
/// Whether to parse the '&' delimiter as a parent selector.
fn parse_parent_selector(&self) -> bool {
false
}
/// Whether the given function name is an alias for the `:is()` function.
fn is_is_alias(&self, _name: &str) -> bool {
false
@ -431,7 +439,8 @@ impl<Impl: SelectorImpl> SelectorList<Impl> {
}
/// Creates a SelectorList from a Vec of selectors. Used in tests.
pub fn from_vec(v: Vec<Selector<Impl>>) -> Self {
#[allow(dead_code)]
pub(crate) fn from_vec(v: Vec<Selector<Impl>>) -> Self {
SelectorList(SmallVec::from_vec(v))
}
}
@ -626,11 +635,21 @@ impl<Impl: SelectorImpl> Selector<Impl> {
self.0.header.header.specificity()
}
#[inline]
fn flags(&self) -> SelectorFlags {
self.0.header.header.flags
}
#[inline]
pub fn has_pseudo_element(&self) -> bool {
self.0.header.header.has_pseudo_element()
}
#[inline]
pub fn has_parent_selector(&self) -> bool {
self.0.header.header.has_parent_selector()
}
#[inline]
pub fn is_slotted(&self) -> bool {
self.0.header.header.is_slotted()
@ -785,7 +804,7 @@ impl<Impl: SelectorImpl> Selector<Impl> {
}
/// Creates a Selector from a vec of Components, specified in parse order. Used in tests.
#[allow(unused)]
#[allow(dead_code)]
pub(crate) fn from_vec(
vec: Vec<Component<Impl>>,
specificity: u32,
@ -803,6 +822,166 @@ impl<Impl: SelectorImpl> Selector<Impl> {
Selector(builder.build_with_specificity_and_flags(spec))
}
pub fn replace_parent_selector(&self, parent: &[Selector<Impl>]) -> Cow<Self> {
if !self.has_parent_selector() {
return Cow::Borrowed(self);
}
// FIXME(emilio): Shouldn't allow replacing if parent has a pseudo-element selector
// or what not.
let flags = self.flags() - SelectorFlags::HAS_PARENT;
let mut specificity = Specificity::from(self.specificity());
let parent_specificity =
Specificity::from(selector_list_specificity_and_flags(parent).specificity());
// The specificity at this point will be wrong, we replace it by the correct one after the
// fact.
let specificity_and_flags = SpecificityAndFlags {
specificity: self.specificity(),
flags,
};
fn replace_parent_on_selector_list<Impl: SelectorImpl>(
orig: &[Selector<Impl>],
parent: &[Selector<Impl>],
specificity: &mut Specificity,
with_specificity: bool,
) -> Vec<Selector<Impl>> {
let mut any = false;
let result = orig
.iter()
.map(|s| {
if !s.has_parent_selector() {
return s.clone();
}
any = true;
s.replace_parent_selector(parent).into_owned()
})
.collect();
if !any || !with_specificity {
return result;
}
*specificity += Specificity::from(
selector_list_specificity_and_flags(&result).specificity -
selector_list_specificity_and_flags(orig).specificity,
);
result
}
fn replace_parent_on_selector<Impl: SelectorImpl>(
orig: &Selector<Impl>,
parent: &[Selector<Impl>],
specificity: &mut Specificity,
) -> Selector<Impl> {
let new_selector = orig.replace_parent_selector(parent);
if matches!(new_selector, Cow::Owned(..)) {
*specificity += Specificity::from(new_selector.specificity() - orig.specificity());
}
new_selector.into_owned()
}
let iter = self.iter_raw_match_order().map(|component| {
use self::Component::*;
match *component {
LocalName(..) |
ID(..) |
Class(..) |
AttributeInNoNamespaceExists { .. } |
AttributeInNoNamespace { .. } |
AttributeOther(..) |
ExplicitUniversalType |
ExplicitAnyNamespace |
ExplicitNoNamespace |
DefaultNamespace(..) |
Namespace(..) |
Root |
Empty |
Scope |
Nth(..) |
NonTSPseudoClass(..) |
PseudoElement(..) |
Combinator(..) |
Host(None) |
Part(..) => component.clone(),
ParentSelector => {
specificity += parent_specificity;
Is(parent.to_vec().into_boxed_slice())
},
Negation(ref selectors) => {
Negation(
replace_parent_on_selector_list(
selectors,
parent,
&mut specificity,
/* with_specificity = */ true,
)
.into_boxed_slice(),
)
},
Is(ref selectors) => {
Is(replace_parent_on_selector_list(
selectors,
parent,
&mut specificity,
/* with_specificity = */ true,
)
.into_boxed_slice())
},
Where(ref selectors) => {
Where(
replace_parent_on_selector_list(
selectors,
parent,
&mut specificity,
/* with_specificity = */ false,
)
.into_boxed_slice(),
)
},
Has(ref selectors) => {
Has(replace_parent_on_selector_list(
selectors,
parent,
&mut specificity,
/* with_specificity = */ true,
)
.into_boxed_slice())
},
Host(Some(ref selector)) => Host(Some(replace_parent_on_selector(
selector,
parent,
&mut specificity,
))),
NthOf(ref data) => {
let selectors = replace_parent_on_selector_list(
data.selectors(),
parent,
&mut specificity,
/* with_specificity = */ true,
);
NthOf(NthOfSelectorData::new(
data.nth_data(),
selectors.into_iter(),
))
},
Slotted(ref selector) => Slotted(replace_parent_on_selector(
selector,
parent,
&mut specificity,
)),
}
});
let header = HeaderWithLength::new(specificity_and_flags, iter.len());
let mut items = UniqueArc::from_header_and_iter(header, iter);
items.header_mut().specificity = specificity.into();
Cow::Owned(Selector(items.shareable_thin()))
}
/// Returns count of simple selectors and combinators in the Selector.
#[inline]
pub fn len(&self) -> usize {
@ -1173,11 +1352,11 @@ pub struct NthOfSelectorData<Impl: SelectorImpl>(
impl<Impl: SelectorImpl> NthOfSelectorData<Impl> {
/// Returns selector data for :nth-{,last-}{child,of-type}(An+B [of S])
#[inline]
pub fn new(nth_data: &NthSelectorData, mut selectors: SelectorList<Impl>) -> Self {
Self(ThinArc::from_header_and_iter(
*nth_data,
selectors.0.drain(..),
))
pub fn new<I>(nth_data: &NthSelectorData, selectors: I) -> Self
where
I: Iterator<Item = Selector<Impl>> + ExactSizeIterator,
{
Self(ThinArc::from_header_and_iter(*nth_data, selectors))
}
/// Returns the An+B part of the selector
@ -1238,6 +1417,7 @@ pub enum Component<Impl: SelectorImpl> {
Root,
Empty,
Scope,
ParentSelector,
Nth(NthSelectorData),
NthOf(NthOfSelectorData<Impl>),
NonTSPseudoClass(#[cfg_attr(feature = "shmem", shmem(field_bound))] Impl::NonTSPseudoClass),
@ -1456,7 +1636,12 @@ impl<Impl: SelectorImpl> Debug for Selector<Impl> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str("Selector(")?;
self.to_css(f)?;
write!(f, ", specificity = 0x{:x})", self.specificity())
write!(
f,
", specificity = {:#x}, flags = {:?})",
self.specificity(),
self.flags()
)
}
}
@ -1717,6 +1902,7 @@ impl<Impl: SelectorImpl> ToCss for Component<Impl> {
Root => dest.write_str(":root"),
Empty => dest.write_str(":empty"),
Scope => dest.write_str(":scope"),
ParentSelector => dest.write_char('&'),
Host(ref selector) => {
dest.write_str(":host")?;
if let Some(ref selector) = *selector {
@ -1832,9 +2018,6 @@ where
{
let mut builder = SelectorBuilder::default();
let mut has_pseudo_element = false;
let mut slotted = false;
let mut part = false;
'outer_loop: loop {
// Parse a sequence of simple selectors.
let empty = parse_compound_selector(parser, &mut state, input, &mut builder)?;
@ -1847,10 +2030,11 @@ where
}
if state.intersects(SelectorParsingState::AFTER_PSEUDO) {
has_pseudo_element = state.intersects(SelectorParsingState::AFTER_PSEUDO_ELEMENT);
slotted = state.intersects(SelectorParsingState::AFTER_SLOTTED);
part = state.intersects(SelectorParsingState::AFTER_PART);
debug_assert!(has_pseudo_element || slotted || part);
debug_assert!(state.intersects(
SelectorParsingState::AFTER_PSEUDO_ELEMENT |
SelectorParsingState::AFTER_SLOTTED |
SelectorParsingState::AFTER_PART
));
break;
}
@ -1893,7 +2077,7 @@ where
builder.push_combinator(combinator);
}
Ok(Selector(builder.build(has_pseudo_element, slotted, part)))
Ok(Selector(builder.build()))
}
impl<Impl: SelectorImpl> Selector<Impl> {
@ -2517,7 +2701,7 @@ where
}
// Whitespace between "of" and the selector list is optional
// https://github.com/w3c/csswg-drafts/issues/8285
let selectors = SelectorList::parse_with_state(
let mut selectors = SelectorList::parse_with_state(
parser,
input,
state |
@ -2526,7 +2710,8 @@ where
ParseErrorRecovery::DiscardList,
)?;
Ok(Component::NthOf(NthOfSelectorData::new(
&nth_data, selectors,
&nth_data,
selectors.0.drain(..),
)))
}
@ -2572,20 +2757,23 @@ where
let id = Component::ID(id.as_ref().into());
SimpleSelectorParseResult::SimpleSelector(id)
},
Token::Delim('.') => {
Token::Delim(delim) if delim == '.' || (delim == '&' && parser.parse_parent_selector()) => {
if state.intersects(SelectorParsingState::AFTER_PSEUDO) {
return Err(input.new_custom_error(SelectorParseErrorKind::InvalidState));
}
let location = input.current_source_location();
let class = match *input.next_including_whitespace()? {
Token::Ident(ref class) => class,
ref t => {
let e = SelectorParseErrorKind::ClassNeedsIdent(t.clone());
return Err(location.new_custom_error(e));
},
};
let class = Component::Class(class.as_ref().into());
SimpleSelectorParseResult::SimpleSelector(class)
SimpleSelectorParseResult::SimpleSelector(if delim == '&' {
Component::ParentSelector
} else {
let class = match *input.next_including_whitespace()? {
Token::Ident(ref class) => class,
ref t => {
let e = SelectorParseErrorKind::ClassNeedsIdent(t.clone());
return Err(location.new_custom_error(e));
},
};
Component::Class(class.as_ref().into())
})
},
Token::SquareBracketBlock => {
if state.intersects(SelectorParsingState::AFTER_PSEUDO) {
@ -2884,6 +3072,10 @@ pub mod tests {
true
}
fn parse_parent_selector(&self) -> bool {
true
}
fn parse_part(&self) -> bool {
true
}
@ -2978,12 +3170,11 @@ pub mod tests {
let mut parser_input = ParserInput::new(input);
let result = SelectorList::parse(parser, &mut CssParser::new(&mut parser_input));
if let Ok(ref selectors) = result {
assert_eq!(selectors.0.len(), 1);
// We can't assume that the serialized parsed selector will equal
// the input; for example, if there is no default namespace, '*|foo'
// should serialize to 'foo'.
assert_eq!(
selectors.0[0].to_css_string(),
selectors.to_css_string(),
match expected {
Some(x) => x,
None => input,
@ -3493,6 +3684,31 @@ pub mod tests {
assert!(parse_expected("foo:where(::before)", Some("foo:where()")).is_ok());
}
#[test]
fn parent_selector() {
assert!(parse("foo &").is_ok());
assert_eq!(
parse("#foo &.bar"),
Ok(SelectorList::from_vec(vec![Selector::from_vec(
vec![
Component::ID(DummyAtom::from("foo")),
Component::Combinator(Combinator::Descendant),
Component::ParentSelector,
Component::Class(DummyAtom::from("bar")),
],
(1 << 20) + (1 << 10) + (0 << 0),
SelectorFlags::HAS_PARENT
)]))
);
let parent = parse(".bar, div .baz").unwrap();
let child = parse("#foo &.bar").unwrap();
assert_eq!(
SelectorList::from_vec(vec![child.0[0].replace_parent_selector(&parent.0).into_owned()]),
parse("#foo :is(.bar, div .baz).bar").unwrap()
);
}
#[test]
fn test_pseudo_iter() {
let selector = &parse("q::before").unwrap().0[0];

26
components/servo_arc/lib.rs
View file

@ -1048,6 +1048,32 @@ impl<H, T> Arc<HeaderSliceWithLength<H, [T]>> {
}
}
impl<H, T> UniqueArc<HeaderSliceWithLength<H, [T]>> {
#[inline]
pub fn from_header_and_iter<I>(header: HeaderWithLength<H>, items: I) -> Self
where
I: Iterator<Item = T> + ExactSizeIterator,
{
Self(Arc::from_header_and_iter(header, items))
}
/// Returns a mutable reference to the header.
pub fn header_mut(&mut self) -> &mut H {
// We know this to be uniquely owned
unsafe { &mut (*self.0.ptr()).data.header.header }
}
/// Returns a mutable reference to the slice.
pub fn data_mut(&mut self) -> &mut [T] {
// We know this to be uniquely owned
unsafe { &mut (*self.0.ptr()).data.slice }
}
pub fn shareable_thin(self) -> ThinArc<H, T> {
Arc::into_thin(self.0)
}
}
impl<H: PartialEq, T: PartialEq> PartialEq for ThinArc<H, T> {
#[inline]
fn eq(&self, other: &ThinArc<H, T>) -> bool {