devela::_dep::memchr::memmem

Enum Prefilter

#[non_exhaustive]pub enum Prefilter {
    None,
    Auto,
}

Available on crate feature dep_memchr only.

Expand description

Prefilter controls whether heuristics are used to accelerate searching.

A prefilter refers to the idea of detecting candidate matches very quickly, and then confirming whether those candidates are full matches. This idea can be quite effective since it’s often the case that looking for candidates can be a lot faster than running a complete substring search over the entire input. Namely, looking for candidates can be done with extremely fast vectorized code.

The downside of a prefilter is that it assumes false positives (which are candidates generated by a prefilter that aren’t matches) are somewhat rare relative to the frequency of full matches. That is, if a lot of false positives are generated, then it’s possible for search time to be worse than if the prefilter wasn’t enabled in the first place.

Another downside of a prefilter is that it can result in highly variable performance, where some cases are extraordinarily fast and others aren’t. Typically, variable performance isn’t a problem, but it may be for your use case.

The use of prefilters in this implementation does use a heuristic to detect when a prefilter might not be carrying its weight, and will dynamically disable its use. Nevertheless, this configuration option gives callers the ability to disable prefilters if you have knowledge that they won’t be useful.

Variants (Non-exhaustive)§

This enum is marked as non-exhaustive

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

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None

Never used a prefilter in substring search.

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Auto

Automatically detect whether a heuristic prefilter should be used. If it is used, then heuristics will be used to dynamically disable the prefilter if it is believed to not be carrying its weight.

Trait Implementations§

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impl Clone for PrefilterConfig

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fn clone(&self) -> PrefilterConfig

Returns a copy of the value. Read more

1.0.0 · Source§

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

Performs copy-assignment from source. Read more

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impl Debug for PrefilterConfig

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

Formats the value using the given formatter. Read more

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impl Default for PrefilterConfig

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fn default() -> PrefilterConfig

Returns the “default value” for a type. Read more

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impl Copy for PrefilterConfig

Auto Trait Implementations§

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Enum PrefilterCopy item path

Variants (Non-exhaustive)§

None

Auto

Trait Implementations§

impl Clone for PrefilterConfig

fn clone(&self) -> PrefilterConfig

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

impl Debug for PrefilterConfig

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

impl Default for PrefilterConfig

fn default() -> PrefilterConfig

impl Copy for PrefilterConfig

Auto Trait Implementations§

impl Freeze for PrefilterConfig

impl RefUnwindSafe for PrefilterConfig

impl Send for PrefilterConfig

impl Sync for PrefilterConfig

impl Unpin for PrefilterConfig

impl UnwindSafe for PrefilterConfig

Blanket Implementations§

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

fn type_id(&self) -> TypeId

impl<T> ArchivePointee for T

type ArchivedMetadata = ()

fn pointer_metadata( _: &<T as ArchivePointee>::ArchivedMetadata, ) -> <T as Pointee>::Metadata

impl<T> Borrow<T> for Twhere T: ?Sized,

fn borrow(&self) -> &T

impl<T> BorrowMut<T> for Twhere T: ?Sized,

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

impl<T> ByteSized for T

const BYTE_ALIGN: usize = _

const BYTE_SIZE: usize = _

fn byte_align(&self) -> usize ⓘ

fn byte_size(&self) -> usize ⓘ

fn ptr_size_ratio(&self) -> [usize; 2]

impl<T, R> Chain<R> for Twhere T: ?Sized,

fn chain<F>(self, f: F) -> Rwhere F: FnOnce(Self) -> R, Self: Sized,

fn chain_ref<F>(&self, f: F) -> Rwhere F: FnOnce(&Self) -> R,

fn chain_mut<F>(&mut self, f: F) -> Rwhere F: FnOnce(&mut Self) -> R,

impl<T> CloneToUninit for Twhere T: Clone,

unsafe fn clone_to_uninit(&self, dst: *mut u8)

impl<T> ExtAny for Twhere T: Any + ?Sized,

fn type_id() -> TypeId

fn type_of(&self) -> TypeId

fn type_name(&self) -> &'static str ⓘ

fn type_is<T: 'static>(&self) -> bool

fn as_any_ref(&self) -> &dyn Anywhere Self: Sized,

fn as_any_mut(&mut self) -> &mut dyn Anywhere Self: Sized,

fn as_any_box(self: Box<Self>) -> Box<dyn Any>where Self: Sized,

fn downcast_ref<T: 'static>(&self) -> Option<&T> ⓘ

fn downcast_mut<T: 'static>(&mut self) -> Option<&mut T> ⓘ

impl<T> ExtMem for Twhere T: ?Sized,

const NEEDS_DROP: bool = _

fn mem_align_of<T>() -> usize ⓘ

fn mem_align_of_val(&self) -> usize ⓘ

fn mem_size_of<T>() -> usize ⓘ

fn mem_size_of_val(&self) -> usize ⓘ

fn mem_copy(&self) -> Selfwhere Self: Copy,

fn mem_needs_drop(&self) -> bool

fn mem_drop(self)where Self: Sized,

fn mem_forget(self)where Self: Sized,

fn mem_replace(&mut self, other: Self) -> Selfwhere Self: Sized,

fn mem_take(&mut self) -> Selfwhere Self: Default,

fn mem_swap(&mut self, other: &mut Self)where Self: Sized,

unsafe fn mem_zeroed<T>() -> T

unsafe fn mem_transmute_copy<Src, Dst>(src: &Src) -> Dst

fn mem_as_bytes(&self) -> &[u8] ⓘwhere Self: Sync + Unpin,

fn mem_as_bytes_mut(&mut self) -> &mut [u8] ⓘwhere Self: Sync + Unpin,

impl<T> From<T> for T

fn from(t: T) -> T

impl<S> FromSample<S> for S

fn from_sample_(s: S) -> S

impl<T> Hook for T

fn hook_ref<F>(self, f: F) -> Selfwhere F: FnOnce(&Self),

fn hook_mut<F>(self, f: F) -> Selfwhere F: FnOnce(&mut Self),

impl<T> Instrument for T

fn instrument(self, span: Span) -> Instrumented<Self> ⓘ

fn in_current_span(self) -> Instrumented<Self> ⓘ

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

Enum Prefilter

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

impl<T> Borrow<T> for T
where T: ?Sized,

impl<T> BorrowMut<T> for T
where T: ?Sized,

impl<T, R> Chain<R> for T
where T: ?Sized,

fn chain<F>(self, f: F) -> R
where F: FnOnce(Self) -> R, Self: Sized,

fn chain_ref<F>(&self, f: F) -> R
where F: FnOnce(&Self) -> R,

fn chain_mut<F>(&mut self, f: F) -> R
where F: FnOnce(&mut Self) -> R,

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

impl<T> ExtAny for T
where T: Any + ?Sized,

fn as_any_ref(&self) -> &dyn Any
where Self: Sized,

fn as_any_mut(&mut self) -> &mut dyn Any
where Self: Sized,

fn as_any_box(self: Box<Self>) -> Box<dyn Any>
where Self: Sized,

impl<T> ExtMem for T
where T: ?Sized,

fn mem_copy(&self) -> Self
where Self: Copy,

fn mem_drop(self)
where Self: Sized,

fn mem_forget(self)
where Self: Sized,

fn mem_replace(&mut self, other: Self) -> Self
where Self: Sized,

fn mem_take(&mut self) -> Self
where Self: Default,

fn mem_swap(&mut self, other: &mut Self)
where Self: Sized,

fn mem_as_bytes(&self) -> &[u8] ⓘ
where Self: Sync + Unpin,

fn mem_as_bytes_mut(&mut self) -> &mut [u8] ⓘ
where Self: Sync + Unpin,

fn hook_ref<F>(self, f: F) -> Self
where F: FnOnce(&Self),

fn hook_mut<F>(self, f: F) -> Self
where F: FnOnce(&mut Self),

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

fn into_either_with<F>(self, into_left: F) -> Either<Self, Self> ⓘ
where F: FnOnce(&Self) -> bool,

impl<F, T> IntoSample<T> for F
where T: FromSample<F>,

impl<T, N1, N2> Niching<NichedOption<T, N1>> for N2
where T: SharedNiching<N1, N2>, N1: Niching<T>, N2: Niching<T>,

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

impl<T, U> ToSample<U> for T
where U: FromSample<T>,

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

impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self> ⓘ
where S: Into<Dispatch>,

impl<S, T> Duplex<S> for T
where T: FromSample<S> + ToSample<S>,

impl<T> Ungil for T
where T: Send,