In Rust, is there a way to iterate through the values of an enum?

You can use the strum crate to easily iterate through the values of an enum.

use strum::IntoEnumIterator; // 0.17.1
use strum_macros::EnumIter; // 0.17.1

#[derive(Debug, EnumIter)]
enum Direction {
    NORTH,
    SOUTH,
    EAST,
    WEST,
}

fn main() {
    for direction in Direction::iter() {
        println!("{:?}", direction);
    }
}

Output:

NORTH
SOUTH
EAST
WEST

If the enum is C-like (as in your example), then you can create a static array of each of the variants and return an iterator of references to them:

use self::Direction::*;
use std::slice::Iter;

#[derive(Debug)]
pub enum Direction {
    North,
    South,
    East,
    West,
}

impl Direction {
    pub fn iterator() -> Iter<'static, Direction> {
        static DIRECTIONS: [Direction; 4] = [North, South, East, West];
        DIRECTIONS.iter()
    }
}

fn main() {
    for dir in Direction::iterator() {
        println!("{:?}", dir);
    }
}

If you make the enum implement Copy, you can use Iterator::copied and return impl Trait to have an iterator of values:

impl Direction {
    pub fn iterator() -> impl Iterator<Item = Direction> {
        [North, South, East, West].iter().copied()
    }
}

See also:

• What is the correct way to return an Iterator (or any other trait)?
• Why can I return a reference to a local literal but not a variable?