array_map 0.4.0

Map backed array for fixed size keys with O(1) performance


no_std compatible Map and Set backed by arrays.

This crate will evolve as more const-generic features become available.

This is especially useful if you have a bare enum where you want to treat each key as a field

use array_map::*;
enum DetectionType {
let thresholds = ArrayMap::<DetectionType, f32, {DetectionType::count()}>::from_closure(|dt| match dt {
    DetectionType::Person => 0.8,
    DetectionType::Vehicle => 0.9,
    DetectionType::Bicycle => 0.7,
let person_threshold = thresholds[DetectionType::Person];

This can also be used to memoize some common computations. (this is 2x as fast as doing the computation on aarch64)

use array_map::*;
let u8_to_f32_cache = ArrayMap::<u8, f32, {u8::SIZE}>::from_closure(|u|f32::from(*u) / 255.0);
let bytes = vec![0_u8; 1024];
// take some bytes and convert them to f32
let floats = bytes.iter().copied().map(|b|u8_to_f32_cache[b]).collect::<Vec<_>>();