Enum tracing_core::stdlib::collections::hash_map::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)

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.