Struct hashbrown::hash_table::AbsentEntry

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

Type representing the absence of an entry, as returned by HashTable::find_entry.

This type only exists due to limitations in Rust’s NLL borrow checker. In the future, find_entry will return an Option<OccupiedEntry> and this type will be removed.

§Examples

use hashbrown::hash_table::{AbsentEntry, Entry};
use hashbrown::{HashTable, DefaultHashBuilder};
use std::hash::BuildHasher;

let mut table: HashTable<&str> = HashTable::new();
let hasher = DefaultHashBuilder::default();
let hasher = |val: &_| hasher.hash_one(val);

let entry_v: AbsentEntry<_, _> = table.find_entry(hasher(&"a"), |&x| x == "a").unwrap_err();
entry_v
    .into_table()
    .insert_unique(hasher(&"a"), "a", hasher);
assert!(table.find(hasher(&"a"), |&x| x == "a").is_some() && table.len() == 1);

// Nonexistent key (insert)
match table.entry(hasher(&"b"), |&x| x == "b", hasher) {
    Entry::Vacant(view) => {
        view.insert("b");
    }
    Entry::Occupied(_) => unreachable!(),
}
assert!(table.find(hasher(&"b"), |&x| x == "b").is_some() && table.len() == 2);

Implementations§

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

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

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

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

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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<'a, T, A> Freeze for AbsentEntry<'a, T, A>

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

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impl<'a, T, A> Send for AbsentEntry<'a, T, A>
where T: Send, A: Send,

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impl<'a, T, A> Sync for AbsentEntry<'a, T, A>
where T: Sync, A: Sync,

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

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

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> 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, 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.