game of life in rust

game_of_life.rs

extern crate rand;

use std::{thread, time};
use rand::Rng;

/*
RULES

For a space that is 'populated':
Each cell with one or no neighbors dies, as if by solitude.
Each cell with four or more neighbors dies, as if by overpopulation.
Each cell with two or three neighbors survives.

For a space that is 'empty' or 'unpopulated'
Each cell with three neighbors becomes populated.

*/

fn print_grid(grid: &Vec<bool>, width: usize) {
    for row in 0..(grid.len() / width) {
        print!("|");
        for col in 0..width {
            let cell = grid[row * width + col];
            print!("{}", if cell {"x"} else {" "});
        }
        println!("|");
    }
    println!("-");
}

fn step(new_grid: &mut Vec<bool>, width: usize) {
    let grid = new_grid.clone();
    let height = grid.len() / width;
    for row in 0..height {
        for col in 0..width {
            let cell = grid[row * width + col];
            let mut neighbors = 0;
            for dx in [-1, 0, 1].iter() {
                for dy in [-1, 0, 1].iter() {
                    if *dx == 0 && *dy == 0 {
                        continue
                    }
                    let new_row = ((row as i32) + dy) % (height as i32);
                    let new_col = ((col as i32) + dx) % (width as i32);
                    if new_col >= (width as i32) || new_col < 0 {
                        continue
                    }
                    if new_row >= (height as i32) || new_row < 0 {
                        continue
                    }
                    if grid[(new_row as usize) * width + (new_col as usize)] {
                        neighbors += 1;
                    }
                }
            }
            if cell {
                if neighbors < 2 || neighbors > 3 {
                    new_grid[row * width + col] = false;
                }
            } else {
                if neighbors == 3 {
                    new_grid[row * width + col] = true;
                }
            }
        }
    }
}

fn main() {

    let mut grid: Vec<bool> = vec![];
    let width = 100;
    let rows = 100;
    let mut rng = rand::thread_rng();
    for _ in 0..(width*rows) {
        grid.push(rng.gen());
    }

    /*
    let mut grid: Vec<bool> = vec![
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, true, true, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, true, true, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, true, true, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, true, true, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false,
        false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false
        
    ];
    let width = 20;
    */

    for _ in 0..200 {
        print!("{}[2J", 27 as char); // clear screen

        print_grid(&grid, width);
        step(&mut grid, width);

        let sleep_time = time::Duration::from_millis(100);
        thread::sleep(sleep_time);
    }
}