Struct style::selector_map::SelectorMap

pub struct SelectorMap<T: 'static> {
    pub root: SmallVec<[T; 1]>,
    pub id_hash: MaybeCaseInsensitiveHashMap<Atom, SmallVec<[T; 1]>>,
    pub class_hash: MaybeCaseInsensitiveHashMap<Atom, SmallVec<[T; 1]>>,
    pub local_name_hash: PrecomputedHashMap<LocalName, SmallVec<[T; 1]>>,
    pub attribute_hash: PrecomputedHashMap<LocalName, SmallVec<[T; 1]>>,
    pub namespace_hash: PrecomputedHashMap<Namespace, SmallVec<[T; 1]>>,
    pub rare_pseudo_classes: SmallVec<[T; 1]>,
    pub other: SmallVec<[T; 1]>,
    pub count: usize,
}

Map element data to selector-providing objects for which the last simple selector starts with them.

e.g., “p > img” would go into the set of selectors corresponding to the element “img” “a .foo .bar.baz” would go into the set of selectors corresponding to the class “bar”

Because we match selectors right-to-left (i.e., moving up the tree from an element), we need to compare the last simple selector in the selector with the element.

So, if an element has ID “id1” and classes “foo” and “bar”, then all the rules it matches will have their last simple selector starting either with “#id1” or with “.foo” or with “.bar”.

Hence, the union of the rules keyed on each of element’s classes, ID, element name, etc. will contain the Selectors that actually match that element.

We use a 1-entry SmallVec to avoid a separate heap allocation in the case where we only have one entry, which is quite common. See measurements in:

• https://bugzilla.mozilla.org/show_bug.cgi?id=1363789#c5
• https://bugzilla.mozilla.org/show_bug.cgi?id=681755

TODO: Tune the initial capacity of the HashMap

Fields

root: SmallVec<[T; 1]>

Rules that have :root selectors.

id_hash: MaybeCaseInsensitiveHashMap<Atom, SmallVec<[T; 1]>>

A hash from an ID to rules which contain that ID selector.

class_hash: MaybeCaseInsensitiveHashMap<Atom, SmallVec<[T; 1]>>

A hash from a class name to rules which contain that class selector.

local_name_hash: PrecomputedHashMap<LocalName, SmallVec<[T; 1]>>

A hash from local name to rules which contain that local name selector.

attribute_hash: PrecomputedHashMap<LocalName, SmallVec<[T; 1]>>

A hash from attributes to rules which contain that attribute selector.

namespace_hash: PrecomputedHashMap<Namespace, SmallVec<[T; 1]>>

A hash from namespace to rules which contain that namespace selector.

rare_pseudo_classes: SmallVec<[T; 1]>

Rules for pseudo-states that are rare but have global selectors.

other: SmallVec<[T; 1]>

All other rules.

count: usize

The number of entries in this map.

Implementations

impl<T> SelectorMap<T>

pub fn new() -> Self

Trivially constructs an empty SelectorMap.

pub fn shrink_if_needed(&mut self)

Shrink the capacity of the map if needed.

pub fn clear(&mut self)

Clears the hashmap retaining storage.

pub fn is_empty(&self) -> bool

Returns whether there are any entries in the map.

pub fn len(&self) -> usize

Returns the number of entries.

impl SelectorMap<Rule>

pub fn get_all_matching_rules<E>( &self, element: E, rule_hash_target: E, matching_rules_list: &mut ApplicableDeclarationList, matching_context: &mut MatchingContext<'_, E::Impl>, cascade_level: CascadeLevel, cascade_data: &CascadeData, stylist: &Stylist, )

where E: TElement,

Append to rule_list all Rules in self that match element.

Extract matching rules as per element’s ID, classes, tag name, etc.. Sort the Rules at the end to maintain cascading order.

pub(crate) fn get_matching_rules<E>( element: E, rules: &[Rule], matching_rules: &mut ApplicableDeclarationList, matching_context: &mut MatchingContext<'_, E::Impl>, cascade_level: CascadeLevel, cascade_data: &CascadeData, stylist: &Stylist, )

where E: TElement,

Adds rules in rules that match element to the matching_rules list.

impl<T: SelectorMapEntry> SelectorMap<T>

pub fn insert( &mut self, entry: T, quirks_mode: QuirksMode, ) -> Result<(), AllocErr>

Inserts an entry into the correct bucket(s).

pub fn lookup<'a, E, F>( &'a self, element: E, quirks_mode: QuirksMode, relevant_attributes: Option<&mut RelevantAttributes>, f: F, ) -> bool

where E: TElement, F: FnMut(&'a T) -> bool,

Looks up entries by id, class, local name, namespace, and other (in order).

Each entry is passed to the callback, which returns true to continue iterating entries, or false to terminate the lookup.

Returns false if the callback ever returns false.

FIXME(bholley) This overlaps with SelectorMap::get_all_matching_rules, but that function is extremely hot and I’d rather not rearrange it.

fn lookup_with_state<'a, E, F>( &'a self, element: E, element_state: ElementState, quirks_mode: QuirksMode, relevant_attributes: Option<&mut RelevantAttributes>, f: F, ) -> bool

where E: TElement, F: FnMut(&'a T) -> bool,

pub fn lookup_with_additional<'a, E, F>( &'a self, element: E, quirks_mode: QuirksMode, additional_id: Option<&WeakAtom>, additional_classes: &[Atom], additional_states: ElementState, f: F, ) -> bool

where E: TElement, F: FnMut(&'a T) -> bool,

Performs a normal lookup, and also looks up entries for the passed-in id and classes.

Each entry is passed to the callback, which returns true to continue iterating entries, or false to terminate the lookup.

Returns false if the callback ever returns false.

Trait Implementations

impl<T: Clone + 'static> Clone for SelectorMap<T>

fn clone(&self) -> SelectorMap<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug + 'static> Debug for SelectorMap<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: 'static> Default for SelectorMap<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T> MallocSizeOf for SelectorMap<T>

where T: MallocSizeOf + 'static,

fn size_of(&self, ops: &mut MallocSizeOfOps) -> usize

Measure the heap usage of all descendant heap-allocated structures, but not the space taken up by the value itself.