pub struct AncestorHashes {
    pub packed_hashes: [u32; 3],
}
Expand description

Ancestor hashes for the bloom filter. We precompute these and store them inline with selectors to optimize cache performance during matching. This matters a lot.

We use 4 hashes, which is copied from Gecko, who copied it from WebKit. Note that increasing the number of hashes here will adversely affect the cache hit when fast-rejecting long lists of Rules with inline hashes.

Because the bloom filter only uses the bottom 24 bits of the hash, we pack the fourth hash into the upper bits of the first three hashes in order to shrink Rule (whose size matters a lot). This scheme minimizes the runtime overhead of the packing for the first three hashes (we just need to mask off the upper bits) at the expense of making the fourth somewhat more complicated to assemble, because we often bail out before checking all the hashes.

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§packed_hashes: [u32; 3]

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impl AncestorHashes

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pub fn new<Impl: SelectorImpl>( selector: &Selector<Impl>, quirks_mode: QuirksMode ) -> Self

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pub fn fourth_hash(&self) -> u32

Returns the fourth hash, reassembled from parts.

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impl Clone for AncestorHashes

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fn clone(&self) -> AncestorHashes

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for AncestorHashes

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

Formats the value using the given formatter. Read more
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impl PartialEq for AncestorHashes

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fn eq(&self, other: &AncestorHashes) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl Eq for AncestorHashes

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impl StructuralPartialEq for AncestorHashes

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.