An exhaustive map for types with finite inhabitants.
Example usage:
use exhaustive_map::ExhaustiveMap;
let mut map = ExhaustiveMap::<u8, u16>::from_fn(|i| i as u16 + 100);
assert_eq!(map.len(), 256);
assert_eq!(map[3], 103);
map[7] = 9999;
assert_eq!(map[7], 9999);
map.swap(7, 3);
assert_eq!(map[3], 9999);
assert_eq!(map[7], 103);
The key type must implement the Finite
trait.
You can implement this for your own types using derive:
use exhaustive_map::{Finite, FiniteExt};
#[derive(Finite, Debug, PartialEq)]
enum Color {
Red,
Green,
Blue,
}
let all: Vec<_> = Color::iter_all().collect();
assert_eq!(all, vec![Color::Red, Color::Green, Color::Blue]);
The Finite
trait can also be implemented manually:
use exhaustive_map::Finite;
#[derive(Debug, PartialEq)]
enum Color {
Red,
Green,
Blue,
}
impl Finite for Color {
const INHABITANTS: usize = 3;
fn to_usize(&self) -> usize {
match self {
Self::Red => 0,
Self::Green => 1,
Self::Blue => 2,
}
}
fn from_usize(i: usize) -> Option<Self> {
Some(match i {
0 => Self::Red,
1 => Self::Green,
2 => Self::Blue,
_ => return None,
})
}
}