Struct VacantEntry

pub struct VacantEntry<'a, T> { /* private fields */ }

A handle to a vacant entry in a Slab.

VacantEntry allows constructing values with the key that they will be assigned to.

Examples

let mut slab = Slab::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);

Implementations

impl<'a, T> VacantEntry<'a, T>

pub fn insert(self, val: T) -> &'a mut T

Insert a value in the entry, returning a mutable reference to the value.

To get the key associated with the value, use key prior to calling insert.

Examples

let mut slab = Slab::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 key(&self) -> usize

Return the key associated with this entry.

A value stored in this entry will be associated with this key.

Examples

let mut slab = Slab::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);

Trait Implementations

impl<'a, T: Debug> Debug for VacantEntry<'a, T>

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

Formats the value using the given formatter.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 16 bytes