Type Definition bevy_utils::HashMap

pub type HashMap<K, V> = HashMap<K, V, RandomState>;

A HashMap implementing aHash, a high speed keyed hashing algorithm intended for use in in-memory hashmaps.

aHash is designed for performance and is NOT cryptographically secure.

Construction

Users may be surprised when a HashMap cannot be constructed with HashMap::new():

use bevy_utils::HashMap;

// Produces an error like "no function or associated item named `new` found [...]"
let map: HashMap<String, String> = HashMap::new();

The standard library’s HashMap::new is implemented only for HashMaps which use the DefaultHasher, so it’s not available for Bevy’s HashMap.

However, an empty HashMap can easily be constructed using the Default implementation:

use bevy_utils::HashMap;

// This works!
let map: HashMap<String, String> = HashMap::default();
assert!(map.is_empty());

Trait Implementations

impl<K, V> AHashExt for HashMap<K, V>

fn with_capacity(capacity: usize) -> Self

Creates an empty HashMap with the specified capacity with aHash.

The hash map will be able to hold at least capacity elements without reallocating. If capacity is 0, the hash map will not allocate.

Examples

use bevy_utils::{HashMap, AHashExt};
let mut map: HashMap<&str, i32> = HashMap::with_capacity(10);
assert!(map.capacity() >= 10);