Struct bevy::utils::hashbrown::hash_table::OccupiedEntry

pub struct OccupiedEntry<'a, T, A = Global>
where A: Allocator,
{ /* private fields */ }
Expand description

A view into an occupied entry in a HashTable. It is part of the Entry enum.

§Examples

use ahash::AHasher;
use hashbrown::hash_table::{Entry, HashTable, OccupiedEntry};
use std::hash::{BuildHasher, BuildHasherDefault};

let mut table = HashTable::new();
let hasher = BuildHasherDefault::<AHasher>::default();
let hasher = |val: &_| hasher.hash_one(val);
for x in ["a", "b", "c"] {
    table.insert_unique(hasher(&x), x, hasher);
}
assert_eq!(table.len(), 3);

let _entry_o: OccupiedEntry<_, _> = table.find_entry(hasher(&"a"), |&x| x == "a").unwrap();
assert_eq!(table.len(), 3);

// Existing key
match table.entry(hasher(&"a"), |&x| x == "a", hasher) {
    Entry::Vacant(_) => unreachable!(),
    Entry::Occupied(view) => {
        assert_eq!(view.get(), &"a");
    }
}

assert_eq!(table.len(), 3);

// Existing key (take)
match table.entry(hasher(&"c"), |&x| x == "c", hasher) {
    Entry::Vacant(_) => unreachable!(),
    Entry::Occupied(view) => {
        assert_eq!(view.remove().0, "c");
    }
}
assert_eq!(table.find(hasher(&"c"), |&x| x == "c"), None);
assert_eq!(table.len(), 2);

Implementations§

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impl<'a, T, A> OccupiedEntry<'a, T, A>
where A: Allocator,

pub fn remove(self) -> (T, VacantEntry<'a, T, A>)

Takes the value out of the entry, and returns it along with a VacantEntry that can be used to insert another value with the same hash as the one that was just removed.

§Examples
use ahash::AHasher;
use hashbrown::hash_table::Entry;
use hashbrown::HashTable;
use std::hash::{BuildHasher, BuildHasherDefault};

let mut table: HashTable<&str> = HashTable::new();
let hasher = BuildHasherDefault::<AHasher>::default();
let hasher = |val: &_| hasher.hash_one(val);
// The table is empty
assert!(table.is_empty() && table.capacity() == 0);

table.insert_unique(hasher(&"poneyland"), "poneyland", hasher);
let capacity_before_remove = table.capacity();

if let Entry::Occupied(o) = table.entry(hasher(&"poneyland"), |&x| x == "poneyland", hasher) {
    assert_eq!(o.remove().0, "poneyland");
}

assert!(table
    .find(hasher(&"poneyland"), |&x| x == "poneyland")
    .is_none());
// Now table hold none elements but capacity is equal to the old one
assert!(table.len() == 0 && table.capacity() == capacity_before_remove);

pub fn get(&self) -> &T

Gets a reference to the value in the entry.

§Examples
use ahash::AHasher;
use hashbrown::hash_table::Entry;
use hashbrown::HashTable;
use std::hash::{BuildHasher, BuildHasherDefault};

let mut table: HashTable<&str> = HashTable::new();
let hasher = BuildHasherDefault::<AHasher>::default();
let hasher = |val: &_| hasher.hash_one(val);
table.insert_unique(hasher(&"poneyland"), "poneyland", hasher);

match table.entry(hasher(&"poneyland"), |&x| x == "poneyland", hasher) {
    Entry::Vacant(_) => panic!(),
    Entry::Occupied(entry) => assert_eq!(entry.get(), &"poneyland"),
}

pub fn get_mut(&mut self) -> &mut T

Gets a mutable reference to the value in the entry.

If you need a reference to the OccupiedEntry which may outlive the destruction of the Entry value, see into_mut.

§Examples
use ahash::AHasher;
use hashbrown::hash_table::Entry;
use hashbrown::HashTable;
use std::hash::{BuildHasher, BuildHasherDefault};

let mut table: HashTable<(&str, u32)> = HashTable::new();
let hasher = BuildHasherDefault::<AHasher>::default();
let hasher = |val: &_| hasher.hash_one(val);
table.insert_unique(hasher(&"poneyland"), ("poneyland", 12), |(k, _)| hasher(&k));

assert_eq!(
    table.find(hasher(&"poneyland"), |&(x, _)| x == "poneyland",),
    Some(&("poneyland", 12))
);

if let Entry::Occupied(mut o) = table.entry(
    hasher(&"poneyland"),
    |&(x, _)| x == "poneyland",
    |(k, _)| hasher(&k),
) {
    o.get_mut().1 += 10;
    assert_eq!(o.get().1, 22);

    // We can use the same Entry multiple times.
    o.get_mut().1 += 2;
}

assert_eq!(
    table.find(hasher(&"poneyland"), |&(x, _)| x == "poneyland",),
    Some(&("poneyland", 24))
);

pub fn into_mut(self) -> &'a mut T

Converts the OccupiedEntry into a mutable reference to the value in the entry with a lifetime bound to the table itself.

If you need multiple references to the OccupiedEntry, see get_mut.

§Examples
use ahash::AHasher;
use hashbrown::hash_table::Entry;
use hashbrown::HashTable;
use std::hash::{BuildHasher, BuildHasherDefault};

let mut table: HashTable<(&str, u32)> = HashTable::new();
let hasher = BuildHasherDefault::<AHasher>::default();
let hasher = |val: &_| hasher.hash_one(val);
table.insert_unique(hasher(&"poneyland"), ("poneyland", 12), |(k, _)| hasher(&k));

assert_eq!(
    table.find(hasher(&"poneyland"), |&(x, _)| x == "poneyland",),
    Some(&("poneyland", 12))
);

let value: &mut (&str, u32);
match table.entry(
    hasher(&"poneyland"),
    |&(x, _)| x == "poneyland",
    |(k, _)| hasher(&k),
) {
    Entry::Occupied(entry) => value = entry.into_mut(),
    Entry::Vacant(_) => panic!(),
}
value.1 += 10;

assert_eq!(
    table.find(hasher(&"poneyland"), |&(x, _)| x == "poneyland",),
    Some(&("poneyland", 22))
);

pub fn into_table(self) -> &'a mut HashTable<T, A>

Converts the OccupiedEntry into a mutable reference to the underlying table.

Trait Implementations§

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impl<T, A> Debug for OccupiedEntry<'_, T, A>
where T: Debug, A: Allocator,

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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<T, A> Send for OccupiedEntry<'_, T, A>
where T: Send, A: Send + Allocator,

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impl<T, A> Sync for OccupiedEntry<'_, T, A>
where T: Sync, A: Sync + Allocator,

Auto Trait Implementations§

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impl<'a, T, A> Freeze for OccupiedEntry<'a, T, A>

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impl<'a, T, A> RefUnwindSafe for OccupiedEntry<'a, T, A>

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impl<'a, T, A> Unpin for OccupiedEntry<'a, T, A>

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impl<'a, T, A = Global> !UnwindSafe for OccupiedEntry<'a, T, A>

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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, U> AsBindGroupShaderType<U> for T
where U: ShaderType, &'a T: for<'a> Into<U>,

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fn as_bind_group_shader_type(&self, _images: &RenderAssets<GpuImage>) -> U

Return the T ShaderType for self. When used in AsBindGroup derives, it is safe to assume that all images in self exist.
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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> Downcast<T> for T

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fn downcast(&self) -> &T

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impl<T> Downcast for T
where T: Any,

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fn into_any(self: Box<T>) -> Box<dyn Any>

Convert Box<dyn Trait> (where Trait: Downcast) to Box<dyn Any>. Box<dyn Any> can then be further downcast into Box<ConcreteType> where ConcreteType implements Trait.
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fn into_any_rc(self: Rc<T>) -> Rc<dyn Any>

Convert Rc<Trait> (where Trait: Downcast) to Rc<Any>. Rc<Any> can then be further downcast into Rc<ConcreteType> where ConcreteType implements Trait.
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Convert &Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &Any’s vtable from &Trait’s.
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fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)

Convert &mut Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &mut Any’s vtable from &mut Trait’s.
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impl<T> DowncastSync for T
where T: Any + Send + Sync,

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fn into_any_arc(self: Arc<T>) -> Arc<dyn Any + Sync + Send>

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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<S> FromSample<S> for S

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fn from_sample_(s: S) -> S

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impl<T> Instrument for T

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

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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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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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
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Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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The alignment of pointer.
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The type for initializers.
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Initializes a with the given initializer. Read more
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Dereferences the given pointer. Read more
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Mutably dereferences the given pointer. Read more
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Drops the object pointed to by the given pointer. Read more
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