Enum hashbrown::hash_map::RawEntryMut

pub enum RawEntryMut<'a, K, V, S> {
    Occupied(RawOccupiedEntryMut<'a, K, V, S>),
    Vacant(RawVacantEntryMut<'a, K, V, S>),
}

A view into a single entry in a map, which may either be vacant or occupied.

This is a lower-level version of Entry.

This enum is constructed through the raw_entry_mut method on HashMap, then calling one of the methods of that RawEntryBuilderMut.

Variants

Occupied(RawOccupiedEntryMut<'a, K, V, S>)

An occupied entry.

Vacant(RawVacantEntryMut<'a, K, V, S>)

A vacant entry.

Implementations

impl<'a, K, V, S> RawEntryMut<'a, K, V, S>

pub fn insert(self, key: K, value: V) -> RawOccupiedEntryMut<'a, K, V, S> where
    K: Hash,
    S: BuildHasher, 

Sets the value of the entry, and returns a RawOccupiedEntryMut.

Examples

use hashbrown::HashMap;

let mut map: HashMap<&str, u32> = HashMap::new();
let entry = map.raw_entry_mut().from_key("horseyland").insert("horseyland", 37);

assert_eq!(entry.remove_entry(), ("horseyland", 37));

pub fn or_insert(self, default_key: K, default_val: V) -> (&'a mut K, &'a mut V) where
    K: Hash,
    S: BuildHasher, 

Ensures a value is in the entry by inserting the default if empty, and returns mutable references to the key and value in the entry.

Examples

use hashbrown::HashMap;

let mut map: HashMap<&str, u32> = HashMap::new();

map.raw_entry_mut().from_key("poneyland").or_insert("poneyland", 3);
assert_eq!(map["poneyland"], 3);

*map.raw_entry_mut().from_key("poneyland").or_insert("poneyland", 10).1 *= 2;
assert_eq!(map["poneyland"], 6);

pub fn or_insert_with<F>(self, default: F) -> (&'a mut K, &'a mut V) where
    F: FnOnce() -> (K, V),
    K: Hash,
    S: BuildHasher, 

Ensures a value is in the entry by inserting the result of the default function if empty, and returns mutable references to the key and value in the entry.

Examples

use hashbrown::HashMap;

let mut map: HashMap<&str, String> = HashMap::new();

map.raw_entry_mut().from_key("poneyland").or_insert_with(|| {
    ("poneyland", "hoho".to_string())
});

assert_eq!(map["poneyland"], "hoho".to_string());

pub fn and_modify<F>(self, f: F) -> Self where
    F: FnOnce(&mut K, &mut V), 

Provides in-place mutable access to an occupied entry before any potential inserts into the map.

Examples

use hashbrown::HashMap;

let mut map: HashMap<&str, u32> = HashMap::new();

map.raw_entry_mut()
   .from_key("poneyland")
   .and_modify(|_k, v| { *v += 1 })
   .or_insert("poneyland", 42);
assert_eq!(map["poneyland"], 42);

map.raw_entry_mut()
   .from_key("poneyland")
   .and_modify(|_k, v| { *v += 1 })
   .or_insert("poneyland", 0);
assert_eq!(map["poneyland"], 43);

pub fn and_replace_entry_with<F>(self, f: F) -> Self where
    F: FnOnce(&K, V) -> Option<V>, 

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

Examples

use hashbrown::HashMap;
use hashbrown::hash_map::RawEntryMut;

let mut map: HashMap<&str, u32> = HashMap::new();

let entry = map
    .raw_entry_mut()
    .from_key("poneyland")
    .and_replace_entry_with(|_k, _v| panic!());

match entry {
    RawEntryMut::Vacant(_) => {},
    RawEntryMut::Occupied(_) => panic!(),
}

map.insert("poneyland", 42);

let entry = map
    .raw_entry_mut()
    .from_key("poneyland")
    .and_replace_entry_with(|k, v| {
        assert_eq!(k, &"poneyland");
        assert_eq!(v, 42);
        Some(v + 1)
    });

match entry {
    RawEntryMut::Occupied(e) => {
        assert_eq!(e.key(), &"poneyland");
        assert_eq!(e.get(), &43);
    },
    RawEntryMut::Vacant(_) => panic!(),
}

assert_eq!(map["poneyland"], 43);

let entry = map
    .raw_entry_mut()
    .from_key("poneyland")
    .and_replace_entry_with(|_k, _v| None);

match entry {
    RawEntryMut::Vacant(_) => {},
    RawEntryMut::Occupied(_) => panic!(),
}

assert!(!map.contains_key("poneyland"));

Trait Implementations

impl<K: Debug, V: Debug, S> Debug for RawEntryMut<'_, K, V, S>

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

Formats the value using the given formatter.