Struct hashbrown::hash_table::AbsentEntry

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

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 ahash::AHasher;
use hashbrown::hash_table::{AbsentEntry, Entry, 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);

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

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

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

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

Trait Implementations

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

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

Formats the value using the given formatter.