Enum RawEntryMut

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

🔬This is a nightly-only experimental API. (hash_raw_entry #56167)

Available on crate feature map only.

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>)

🔬This is a nightly-only experimental API. (hash_raw_entry #56167)

An occupied entry.

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

🔬This is a nightly-only experimental API. (hash_raw_entry #56167)

A vacant entry.

Implementations

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

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

where K: Hash, S: BuildHasher,

🔬This is a nightly-only experimental API. (hash_raw_entry #56167)

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

#![feature(hash_raw_entry)]
use std::collections::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,

🔬This is a nightly-only experimental API. (hash_raw_entry #56167)

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

#![feature(hash_raw_entry)]
use std::collections::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) -> RawEntryMut<'a, K, V, S>

where F: FnOnce(&mut K, &mut V),

🔬This is a nightly-only experimental API. (hash_raw_entry #56167)

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

Examples

#![feature(hash_raw_entry)]
use std::collections::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);

Trait Implementations

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

where K: Debug, V: Debug,

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

Formats the value using the given formatter.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 24 bytes

Size for each variant:

• Occupied: 24 bytes
• Vacant: 24 bytes