Struct super_slab::SuperSlab

pub struct SuperSlab<T> { /* fields omitted */ }

A SuperSlab is a collection of Slabs, viewed as single Slab.

Implementations

impl<T> SuperSlab<T>

pub fn new() -> Self

Construct a new, empty SuperSlab. The function allocates 4 extents with each Slab having a capacity of 4.

Examples

let slab: SuperSlab<i32> = SuperSlab::new();
assert_eq!(slab.capacity(), 16);

pub fn with_capacity_and_extents(
    capacity: usize,
    secondary: usize,
    extents: usize
) -> Self

Construct a new, empty SuperSlab with the specified capacity.

The returned slab will be able to store exactly capacity without allocating an extent. If capacity is 0, a panic will occur.

It is important to note that this function does not specify the length of the returned slab, but only the capacity. For an explanation of the difference between length and capacity, see Capacity and reallocation.

Examples

// allocate with a capacity of 10, reserve 4 extents, each with a capacity of 2
// this produces two allocation, one for the extents (4 slots) and one for
// the primary (10 entries).

let mut slab = SuperSlab::with_capacity_and_extents(10, 2, 4);

// The slab contains no values, even though it has capacity for more
assert_eq!(slab.len(), 0);
assert_eq!(slab.capacity(), 10);

// These are all done without extending...
for i in 0..10 {
    slab.insert(i);
}

// ...but this will make the super slab add an extent
slab.insert(11);
assert_eq!(slab.capacity(), 12);

pub fn with_capacity(capacity: usize) -> Self

Simpler instantiation of a slab. This will extents will be 1/4 of capacity or capacity if capacity is less than or equal to 100.

Examples

// allocate with a capacity of 10, reserve 4 extents, each with a capacity of 10
// this produces two allocation, one for the extents (4 slots) and one for
// the primary (10 entries).

let mut slab = SuperSlab::with_capacity(10);

// The slab contains no values, even though it has capacity for more
assert_eq!(slab.len(), 0);
assert_eq!(slab.capacity(), 10);

// These are all done without extending...
for i in 0..10 {
    slab.insert(i);
}

// ...but this will make the super slab add an extent
slab.insert(11);
assert_eq!(slab.capacity(), 20);

pub fn capacity(&self) -> usize

Return the number of values the slab can store without reallocating.

Examples

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

pub fn clear(&mut self)

reserve is not supported. It seems to have limited value in a SuperSlab. reserve_exact is not supported. It seems to have limited value in a SuperSlab. shrink_to_fit is not supported. It seems to have limited value in a SuperSlab. compact is not supported. It may be supported in the future Clear the slabs of all values.

Examples

let mut slab = SuperSlab::new();

for i in 0..slab.capacity() {
    slab.insert(i);
}

slab.clear();
assert!(slab.is_empty());

pub fn len(&self) -> usize

Return the number of stored values.

Examples

let mut slab = SuperSlab::new();

for i in 0..6 {
    slab.insert(i);
}

assert_eq!(6, slab.len());

pub fn is_empty(&self) -> bool

Return true if there are no values stored in the slab.

Examples

let mut slab = SuperSlab::new();
assert!(slab.is_empty());

slab.insert(1);
assert!(!slab.is_empty());

pub fn iter(&self) -> Iter<'_, T>

Return an iterator over the slabs.

This function should generally be avoided as it is not efficient. Iterators must iterate over every slot in the slab even if it is vacant. As such, a slab with a capacity of 1 million but only one stored value must still iterate the million slots.

Examples

let mut slab = SuperSlab::with_capacity(2);

for i in 0..3 {
    slab.insert(i);
}

let mut iterator = slab.iter();
assert_eq!(iterator.next(), Some((0, &0)));
assert_eq!(iterator.next(), Some((1, &1)));
assert_eq!(iterator.next(), Some((2, &2)));
assert_eq!(iterator.next(), None);

pub fn iter_mut(&mut self) -> IterMut<'_, T>

Return an iterator that allows modifying each value.

This function should generally be avoided as it is not efficient. Iterators must iterate over every slot in the slab even if it is vacant. As such, a slab with a capacity of 1 million but only one stored value must still iterate the million slots.

Examples

let mut slab = SuperSlab::with_capacity(2);

let key1 = slab.insert(0);
let key2 = slab.insert(1);

for (key, val) in slab.iter_mut() {
    if key == key1 {
        *val += 2;
    }
}

assert_eq!(slab[key1], 2);
assert_eq!(slab[key2], 1);

pub fn get(&self, key: usize) -> Option<&T>

Return a reference to the value associated with the given key.

If the given key is not associated with a value, then None is returned.

Examples

let mut slab = SuperSlab::new();
let key = slab.insert("hello");

assert_eq!(slab.get(key), Some(&"hello"));
assert_eq!(slab.get(123), None);

pub fn get_mut(&mut self, key: usize) -> Option<&mut T>

Return a mutable reference to the value associated with the given key.

If the given key is not associated with a value, then None is returned.

Examples

let mut slab = SuperSlab::new();
let key = slab.insert("hello");

*slab.get_mut(key).unwrap() = "world";

assert_eq!(slab[key], "world");
assert_eq!(slab.get_mut(123), None);

pub unsafe fn get_unchecked(&self, key: usize) -> &T

Return a reference to the value associated with the given key without performing bounds checking.

Safety

This function should be used with care.

Examples

let mut slab = SuperSlab::new();
let key = slab.insert(2);

unsafe {
    assert_eq!(slab.get_unchecked(key), &2);
}

pub unsafe fn get_unchecked_mut(&mut self, key: usize) -> &mut T

Return a mutable reference to the value associated with the given key without performing bounds checking.

Safety

This function should be used with care.

Examples

let mut slab = SuperSlab::new();
let key = slab.insert(2);

unsafe {
    let val = slab.get_unchecked_mut(key);
    *val = 13;
}

assert_eq!(slab[key], 13);

pub fn insert(&mut self, val: T) -> usize

key_of is not supported. It may be supported in the future. Insert a value in the slab, returning key assigned to the value.

The returned key can later be used to retrieve or remove the value using indexed lookup and remove. Additional capacity is allocated if needed. See Capacity and reallocation.

Panics

Panics if the number of elements in the vector overflows a usize.

Examples

let mut slab = SuperSlab::new();
let key = slab.insert("hello");
assert_eq!(slab[key], "hello");

pub fn vacant_entry(&mut self) -> VacantEntry<'_, T>

Return a handle to a vacant entry allowing for further manipulation.

This function is useful when creating values that must contain their slab key. The returned VacantEntry reserves a slot in the slab and is able to query the associated key.

Examples

let mut slab = SuperSlab::new();

let hello = {
    let entry = slab.vacant_entry();
    let key = entry.key();

    entry.insert((key, "hello"));
    key
};

assert_eq!(hello, slab[hello].0);
assert_eq!("hello", slab[hello].1);

pub fn remove(&mut self, key: usize) -> T

Remove and return the value associated with the given key.

The key is then released and may be associated with future stored values.

Panics

Panics if key is not associated with a value.

Examples

let mut slab = SuperSlab::new();

let hello = slab.insert("hello");

assert_eq!(slab.remove(hello), "hello");
assert!(!slab.contains(hello));

pub fn contains(&self, key: usize) -> bool

Return true if a value is associated with the given key.

Examples

let mut slab = SuperSlab::new();

let hello = slab.insert("hello");
assert!(slab.contains(hello));

slab.remove(hello);

assert!(!slab.contains(hello));

pub fn retain<F>(&mut self, f: F) where
    F: FnMut(usize, &mut T) -> bool, 

Retain only the elements specified by the predicate.

In other words, remove all elements e such that f(usize, &mut e) returns false. This method operates in place and preserves the key associated with the retained values.

Examples

let mut slab = SuperSlab::with_capacity(2);

let k1 = slab.insert(0);
let k2 = slab.insert(1);
let k3 = slab.insert(2);

slab.retain(|key, val| key == k1 || *val == 1);

assert!(slab.contains(k1));
assert!(slab.contains(k2));
assert!(!slab.contains(k3));

assert_eq!(2, slab.len());

pub fn drain(&mut self) -> Drain<'_, T>

Return a draining iterator that removes all elements from the slab and yields the removed items.

Note: Elements are removed even if the iterator is only partially consumed or not consumed at all.

Examples

let mut slab = SuperSlab::new();

let _ = slab.insert(0);
let _ = slab.insert(1);
let _ = slab.insert(2);

{
    let mut drain = slab.drain();

    assert_eq!(Some(0), drain.next());
    assert_eq!(Some(1), drain.next());
    assert_eq!(Some(2), drain.next());
    assert_eq!(None, drain.next());
}

assert!(slab.is_empty());

Trait Implementations

impl<T: Clone> Clone for SuperSlab<T>

fn clone(&self) -> SuperSlab<T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> Debug for SuperSlab<T> where
    T: Debug, 

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

Formats the value using the given formatter.

impl<T> Default for SuperSlab<T>

fn default() -> Self

Returns the "default value" for a type.

impl<T> Index<usize> for SuperSlab<T>

type Output = T

The returned type after indexing.

fn index(&self, key: usize) -> &T

Performs the indexing (container[index]) operation.

impl<T> IndexMut<usize> for SuperSlab<T>

fn index_mut(&mut self, key: usize) -> &mut T

Performs the mutable indexing (container[index]) operation.

impl<'a, T> IntoIterator for &'a SuperSlab<T>

type Item = (usize, &'a T)

The type of the elements being iterated over.

type IntoIter = Iter<'a, T>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Iter<'a, T>

Creates an iterator from a value.

impl<'a, T> IntoIterator for &'a mut SuperSlab<T>

type Item = (usize, &'a mut T)

The type of the elements being iterated over.

type IntoIter = IterMut<'a, T>

Which kind of iterator are we turning this into?

fn into_iter(self) -> IterMut<'a, T>

Creates an iterator from a value.