Rusty Mars Rover

Cargo.toml

[package]
name = "rover"
version = "0.1.0"
authors = ["David Whitney <[email protected]>"]
edition = "2018"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]

main.rs

/*
5 5       <-- grid size
1 2 N   < -- location of rover
LMLMLMLMM  <---- directions
3 3 E    <--- another rover
MMRMMRMRRM <--- other directions

Output:
1 3 N
5 1 E
*/

pub fn main() {

    calc(1, 2, 'N', "LMLMLMLMM");    
    println!("=======");
    calc(3, 3, 'E', "MMRMMRMRRM");
}

fn calc(x: i32, y: i32, facing: char, instructions: &str) {
    let mut _x = x;
    let mut _y = y;
    let mut _facing = facing;

    let compass: [char; 4] = ['N', 'E', 'S', 'W'];
    let mut _facing_index: i32 = compass.iter().position(|&s| s == _facing).unwrap() as i32;
    let mut iterator = instructions.chars();

    for _i in 0..instructions.chars().count() {
        let ch = iterator.next().unwrap();

        match ch {
            'L' => {
                _facing_index = if _facing_index == 0 {
                    (compass.len() as i32) - 1
                } else {
                    _facing_index - 1
                }
            }
            'R' => {
                _facing_index = if _facing_index == 3 {
                    0
                } else {
                    _facing_index + 1
                }
            }
            'M' => match _facing {
                'N' => _y = _y + 1,
                'E' => _x = _x + 1,
                'S' => _y = _y - 1,
                'W' => _x = _x - 1,
                _ => {}
            },
            _ => {}
        }

        _facing = compass[_facing_index as usize];
    }

    println!("{0}, {1}, {2}", _x, _y, _facing);
}



#[cfg(test)]
mod tests {
    // Note this useful idiom: importing names from outer (for mod tests) scope.
    use super::*;

    #[test]
    fn test_add() {
        // assert_eq!(add(1, 2), 3);
    }
}