Struct stash::UniqueStash

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pub struct UniqueStash<V> { /* private fields */ }

Expand description

An O(1) amortized table that does not reuse keys.

Guarantee: No two calls to put on the same UniqueStash will ever return the same Key.

An example use case is a file descriptor table.

An example use case is a session table where expired session IDs should never be re-used.

Implementations§

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impl<V> UniqueStash<V>

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pub const fn new() -> Self

Constructs a new, empty UniqueStash<T>.

The stash will not allocate until elements are put onto it.

pub fn with_capacity(capacity: usize) -> Self

Constructs a new, empty UniqueStash<T> with the specified capacity.

The stash will be able to hold exactly capacity elements without reallocating. If capacity is 0, the stash will not allocate.

It is important to note that this function does not specify the length of the returned stash , but only the capacity. (For an explanation of the difference between length and capacity, see the main Vec<T> docs in the std::vec module, ‘Capacity and reallocation’.)

Examples

use stash::UniqueStash;

let mut stash: UniqueStash<i32> = UniqueStash::with_capacity(10);

// The stash contains no items, even though it has capacity for more
assert_eq!(stash.len(), 0);

// These are all done without reallocating...
for i in 0i32..10 {
    let _ = stash.put(i);
}

// ...but this may make the stash reallocate
stash.put(11);

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pub fn capacity(&self) -> usize

Returns the number of elements the stash can hold without reallocating.

Examples

use stash::UniqueStash;

let stash: UniqueStash<i32> = UniqueStash::with_capacity(10);
assert_eq!(stash.capacity(), 10);

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pub fn len(&self) -> usize

The number of items in the stash.

Examples

use stash::UniqueStash;

let mut stash = UniqueStash::new();
assert_eq!(stash.len(), 0);
stash.put("a");
assert_eq!(stash.len(), 1);

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pub fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional more elements to be put into the given UniqueStash<T>. The collection may reserve more space to avoid frequent reallocations.

Panics

Panics if the new capacity overflows usize.

Examples

use stash::UniqueStash;

let mut stash: UniqueStash<i32> = UniqueStash::new();
let t1 = stash.put(1);
stash.reserve(10);
assert!(stash.capacity() >= 11);

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pub fn reserve_exact(&mut self, additional: usize)

Reserves the minimum capacity for exactly additional more elements to be put into the given UniqueStash<T>. Does nothing if the capacity is already sufficient.

Note that the allocator may give the collection more space than it requests. Therefore capacity can not be relied upon to be precisely minimal. Prefer reserve if future puts are expected.

Panics

Panics if the new capacity overflows usize.

Examples

use stash::UniqueStash;

let mut stash: UniqueStash<i32> = UniqueStash::new();
let t1 = stash.put(1);
stash.reserve_exact(10);
assert!(stash.capacity() >= 11);

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pub fn put(&mut self, value: V) -> Tag

Put a value into the stash.

Returns the index at which this value was stored.

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pub fn extend(&mut self, iter: I) -> Extend<'_, I> ⓘwhere I: Iterator<Item = V>,

Put all items in the iterator into the stash.

Returns an iterator over the indices where the items were inserted. The items are actually inserted as the Iterator is read. If the returned Iterator is dropped, the rest of the items will be inserted all at once.

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