Struct hashbrown::hash_map::RawOccupiedEntryMut

source · [−]
pub struct RawOccupiedEntryMut<'a, K, V, S, A: Allocator + Clone = Global> { /* private fields */ }
Expand description

A view into an occupied entry in a HashMap. It is part of the RawEntryMut enum.

Examples

use core::hash::{BuildHasher, Hash};
use hashbrown::hash_map::{HashMap, RawEntryMut, RawOccupiedEntryMut};

let mut map = HashMap::new();
map.extend([("a", 10), ("b", 20), ("c", 30)]);

fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
    use core::hash::Hasher;
    let mut state = hash_builder.build_hasher();
    key.hash(&mut state);
    state.finish()
}

let _raw_o: RawOccupiedEntryMut<_, _, _> = map.raw_entry_mut().from_key(&"a").insert("a", 100);
assert_eq!(map.len(), 3);

// Existing key (insert and update)
match map.raw_entry_mut().from_key(&"a") {
    RawEntryMut::Vacant(_) => unreachable!(),
    RawEntryMut::Occupied(mut view) => {
        assert_eq!(view.get(), &100);
        let v = view.get_mut();
        let new_v = (*v) * 10;
        *v = new_v;
        assert_eq!(view.insert(1111), 1000);
    }
}

assert_eq!(map[&"a"], 1111);
assert_eq!(map.len(), 3);

// Existing key (take)
let hash = compute_hash(map.hasher(), &"c");
match map.raw_entry_mut().from_key_hashed_nocheck(hash, &"c") {
    RawEntryMut::Vacant(_) => unreachable!(),
    RawEntryMut::Occupied(view) => {
        assert_eq!(view.remove_entry(), ("c", 30));
    }
}
assert_eq!(map.raw_entry().from_key(&"c"), None);
assert_eq!(map.len(), 2);

let hash = compute_hash(map.hasher(), &"b");
match map.raw_entry_mut().from_hash(hash, |q| *q == "b") {
    RawEntryMut::Vacant(_) => unreachable!(),
    RawEntryMut::Occupied(view) => {
        assert_eq!(view.remove_entry(), ("b", 20));
    }
}
assert_eq!(map.get(&"b"), None);
assert_eq!(map.len(), 1);

Implementations

Gets a reference to the key in the entry.

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};

let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();

match map.raw_entry_mut().from_key(&"a") {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(o) => assert_eq!(o.key(), &"a")
}

Gets a mutable reference to the key in the entry.

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};
use std::rc::Rc;

let key_one = Rc::new("a");
let key_two = Rc::new("a");

let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
map.insert(key_one.clone(), 10);

assert_eq!(map[&key_one], 10);
assert!(Rc::strong_count(&key_one) == 2 && Rc::strong_count(&key_two) == 1);

match map.raw_entry_mut().from_key(&key_one) {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(mut o) => {
        *o.key_mut() = key_two.clone();
    }
}
assert_eq!(map[&key_two], 10);
assert!(Rc::strong_count(&key_one) == 1 && Rc::strong_count(&key_two) == 2);

Converts the entry into a mutable reference to the key in the entry with a lifetime bound to the map itself.

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};
use std::rc::Rc;

let key_one = Rc::new("a");
let key_two = Rc::new("a");

let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
map.insert(key_one.clone(), 10);

assert_eq!(map[&key_one], 10);
assert!(Rc::strong_count(&key_one) == 2 && Rc::strong_count(&key_two) == 1);

let inside_key: &mut Rc<&str>;

match map.raw_entry_mut().from_key(&key_one) {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(o) => inside_key = o.into_key(),
}
*inside_key = key_two.clone();

assert_eq!(map[&key_two], 10);
assert!(Rc::strong_count(&key_one) == 1 && Rc::strong_count(&key_two) == 2);

Gets a reference to the value in the entry.

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};

let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();

match map.raw_entry_mut().from_key(&"a") {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(o) => assert_eq!(o.get(), &100),
}

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

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};

let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();

let value: &mut u32;

match map.raw_entry_mut().from_key(&"a") {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(o) => value = o.into_mut(),
}
*value += 900;

assert_eq!(map[&"a"], 1000);

Gets a mutable reference to the value in the entry.

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};

let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();

match map.raw_entry_mut().from_key(&"a") {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(mut o) => *o.get_mut() += 900,
}

assert_eq!(map[&"a"], 1000);

Gets a reference to the key and value in the entry.

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};

let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();

match map.raw_entry_mut().from_key(&"a") {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(o) => assert_eq!(o.get_key_value(), (&"a", &100)),
}

Gets a mutable reference to the key and value in the entry.

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};
use std::rc::Rc;

let key_one = Rc::new("a");
let key_two = Rc::new("a");

let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
map.insert(key_one.clone(), 10);

assert_eq!(map[&key_one], 10);
assert!(Rc::strong_count(&key_one) == 2 && Rc::strong_count(&key_two) == 1);

match map.raw_entry_mut().from_key(&key_one) {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(mut o) => {
        let (inside_key, inside_value) = o.get_key_value_mut();
        *inside_key = key_two.clone();
        *inside_value = 100;
    }
}
assert_eq!(map[&key_two], 100);
assert!(Rc::strong_count(&key_one) == 1 && Rc::strong_count(&key_two) == 2);

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

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};
use std::rc::Rc;

let key_one = Rc::new("a");
let key_two = Rc::new("a");

let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
map.insert(key_one.clone(), 10);

assert_eq!(map[&key_one], 10);
assert!(Rc::strong_count(&key_one) == 2 && Rc::strong_count(&key_two) == 1);

let inside_key: &mut Rc<&str>;
let inside_value: &mut u32;
match map.raw_entry_mut().from_key(&key_one) {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(o) => {
        let tuple = o.into_key_value();
        inside_key = tuple.0;
        inside_value = tuple.1;
    }
}
*inside_key = key_two.clone();
*inside_value = 100;
assert_eq!(map[&key_two], 100);
assert!(Rc::strong_count(&key_one) == 1 && Rc::strong_count(&key_two) == 2);

Sets the value of the entry, and returns the entry’s old value.

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};

let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();

match map.raw_entry_mut().from_key(&"a") {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(mut o) => assert_eq!(o.insert(1000), 100),
}

assert_eq!(map[&"a"], 1000);

Sets the value of the entry, and returns the entry’s old value.

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};
use std::rc::Rc;

let key_one = Rc::new("a");
let key_two = Rc::new("a");

let mut map: HashMap<Rc<&str>, u32> = HashMap::new();
map.insert(key_one.clone(), 10);

assert_eq!(map[&key_one], 10);
assert!(Rc::strong_count(&key_one) == 2 && Rc::strong_count(&key_two) == 1);

match map.raw_entry_mut().from_key(&key_one) {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(mut o) => {
        let old_key = o.insert_key(key_two.clone());
        assert!(Rc::ptr_eq(&old_key, &key_one));
    }
}
assert_eq!(map[&key_two], 10);
assert!(Rc::strong_count(&key_one) == 1 && Rc::strong_count(&key_two) == 2);

Takes the value out of the entry, and returns it.

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};

let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();

match map.raw_entry_mut().from_key(&"a") {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(o) => assert_eq!(o.remove(), 100),
}
assert_eq!(map.get(&"a"), None);
source

pub fn remove_entry(self) -> (K, V)

Take the ownership of the key and value from the map.

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};

let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();

match map.raw_entry_mut().from_key(&"a") {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(o) => assert_eq!(o.remove_entry(), ("a", 100)),
}
assert_eq!(map.get(&"a"), None);
source

pub fn replace_entry_with<F>(self, f: F) -> RawEntryMut<'a, K, V, S, A>where
    F: FnOnce(&K, V) -> Option<V>,

Provides shared access to the key and owned access to the value of the entry and allows to replace or remove it based on the value of the returned option.

Examples
use hashbrown::hash_map::{HashMap, RawEntryMut};

let mut map: HashMap<&str, u32> = [("a", 100), ("b", 200)].into();

let raw_entry = match map.raw_entry_mut().from_key(&"a") {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(o) => o.replace_entry_with(|k, v| {
        assert_eq!(k, &"a");
        assert_eq!(v, 100);
        Some(v + 900)
    }),
};
let raw_entry = match raw_entry {
    RawEntryMut::Vacant(_) => panic!(),
    RawEntryMut::Occupied(o) => o.replace_entry_with(|k, v| {
        assert_eq!(k, &"a");
        assert_eq!(v, 1000);
        None
    }),
};
match raw_entry {
    RawEntryMut::Vacant(_) => { },
    RawEntryMut::Occupied(_) => panic!(),
};
assert_eq!(map.get(&"a"), None);

Trait Implementations

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Auto Trait Implementations

Blanket Implementations

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Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.