Struct regex_automata::nfa::thompson::backtrack::Cache

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

A cache represents mutable state that a BoundedBacktracker requires during a search.

For a given BoundedBacktracker, its corresponding cache may be created either via BoundedBacktracker::create_cache, or via Cache::new. They are equivalent in every way, except the former does not require explicitly importing Cache.

A particular Cache is coupled with the BoundedBacktracker from which it was created. It may only be used with that BoundedBacktracker. A cache and its allocations may be re-purposed via Cache::reset, in which case, it can only be used with the new BoundedBacktracker (and not the old one).

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impl Cache

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pub fn new(re: &BoundedBacktracker) -> Cache

Create a new BoundedBacktracker cache.

A potentially more convenient routine to create a cache is BoundedBacktracker::create_cache, as it does not require also importing the Cache type.

If you want to reuse the returned Cache with some other BoundedBacktracker, then you must call Cache::reset with the desired BoundedBacktracker.

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pub fn reset(&mut self, re: &BoundedBacktracker)

Reset this cache such that it can be used for searching with different BoundedBacktracker.

A cache reset permits reusing memory already allocated in this cache with a different BoundedBacktracker.

§Example

This shows how to re-purpose a cache for use with a different BoundedBacktracker.

use regex_automata::{
    nfa::thompson::backtrack::BoundedBacktracker,
    Match,
};

let re1 = BoundedBacktracker::new(r"\w")?;
let re2 = BoundedBacktracker::new(r"\W")?;

let mut cache = re1.create_cache();
assert_eq!(
    Some(Ok(Match::must(0, 0..2))),
    re1.try_find_iter(&mut cache, "Δ").next(),
);

// Using 'cache' with re2 is not allowed. It may result in panics or
// incorrect results. In order to re-purpose the cache, we must reset
// it with the BoundedBacktracker we'd like to use it with.
//
// Similarly, after this reset, using the cache with 're1' is also not
// allowed.
cache.reset(&re2);
assert_eq!(
    Some(Ok(Match::must(0, 0..3))),
    re2.try_find_iter(&mut cache, "☃").next(),
);
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pub fn memory_usage(&self) -> usize

Returns the heap memory usage, in bytes, of this cache.

This does not include the stack size used up by this cache. To compute that, use std::mem::size_of::<Cache>().

Trait Implementations§

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impl Clone for Cache

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fn clone(&self) -> Cache

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 Cache

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

Formats the value using the given formatter. Read more

Auto Trait Implementations§

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impl Freeze for Cache

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impl RefUnwindSafe for Cache

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impl Send for Cache

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impl Sync for Cache

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impl Unpin for Cache

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impl UnwindSafe for Cache

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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default 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.