Struct memchr::arch::x86_64::avx2::packedpair::Finder

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pub struct Finder { /* private fields */ }
Expand description

A “packed pair” finder that uses 256-bit vector operations.

This finder picks two bytes that it believes have high predictive power for indicating an overall match of a needle. Depending on whether Finder::find or Finder::find_prefilter is used, it reports offsets where the needle matches or could match. In the prefilter case, candidates are reported whenever the Pair of bytes given matches.

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impl Finder

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pub fn new(needle: &[u8]) -> Option<Finder>

Create a new pair searcher. The searcher returned can either report exact matches of needle or act as a prefilter and report candidate positions of needle.

If AVX2 is unavailable in the current environment or if a Pair could not be constructed from the needle given, then None is returned.

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pub fn with_pair(needle: &[u8], pair: Pair) -> Option<Finder>

Create a new “packed pair” finder using the pair of bytes given.

This constructor permits callers to control precisely which pair of bytes is used as a predicate.

If AVX2 is unavailable in the current environment, then None is returned.

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pub fn is_available() -> bool

Returns true when this implementation is available in the current environment.

When this is true, it is guaranteed that Finder::with_pair will return a Some value. Similarly, when it is false, it is guaranteed that Finder::with_pair will return a None value. Notice that this does not guarantee that Finder::new will return a Finder. Namely, even when Finder::is_available is true, it is not guaranteed that a valid Pair can be found from the needle given.

Note also that for the lifetime of a single program, if this returns true then it will always return true.

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pub fn find(&self, haystack: &[u8], needle: &[u8]) -> Option<usize>

Execute a search using AVX2 vectors and routines.

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When haystack.len() is less than Finder::min_haystack_len.

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pub fn find_prefilter(&self, haystack: &[u8]) -> Option<usize>

Run this finder on the given haystack as a prefilter.

If a candidate match is found, then an offset where the needle could begin in the haystack is returned.

§Panics

When haystack.len() is less than Finder::min_haystack_len.

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pub fn pair(&self) -> &Pair

Returns the pair of offsets (into the needle) used to check as a predicate before confirming whether a needle exists at a particular position.

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pub fn min_haystack_len(&self) -> usize

Returns the minimum haystack length that this Finder can search.

Using a haystack with length smaller than this in a search will result in a panic. The reason for this restriction is that this finder is meant to be a low-level component that is part of a larger substring strategy. In that sense, it avoids trying to handle all cases and instead only handles the cases that it can handle very well.

Trait Implementations§

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impl Clone for Finder

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fn clone(&self) -> Finder

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 Finder

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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 Copy for Finder

Auto Trait Implementations§

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impl Freeze for Finder

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impl RefUnwindSafe for Finder

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impl Send for Finder

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impl Sync for Finder

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impl Unpin for Finder

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impl UnwindSafe for Finder

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> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dst. 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.