conway_v1.rs

extern crate rand;

use rand::Rng;

const WIDTH : usize = 80;
const HEIGH : usize = 40;

const SIZE : usize = WIDTH * HEIGH;

type MatrixLine = [bool; WIDTH];
type Matrix = [MatrixLine; HEIGH];


fn matrix_init() -> Matrix {
    let mut matrix : Matrix = [[false; WIDTH]; HEIGH];
    let mut rng = rand::thread_rng();

    for _ in 0..(SIZE / 2) {
        let x = rng.gen_range(0, WIDTH);
        let y = rng.gen_range(0, HEIGH);
        matrix[y][x] = true;
    }

    matrix
}

fn matrix_render(matrix : Matrix) {
    for row in matrix.iter() {
        for cell in row.iter() {
            let ch = match *cell {
                true => "#",
                false => " ",
            };
            print!("{}", ch);
        }
        println!("");
    }
}

fn matrix_next(matrix : Matrix) -> Matrix {
    let mut result: Matrix = [[false; WIDTH]; HEIGH];
    for (ri, row) in matrix.iter().enumerate() {
        for (ci, cell) in row.iter().enumerate() {
            let alive_count = matrix_count_cell_neighbors(matrix, ri as i32, ci as i32);
            let new_val =
                if *cell {
                    if alive_count < 2 {
                        false
                    } else if alive_count == 2 || alive_count == 3 {
                        true
                    } else {
                        false
                    }
                } else {
                    alive_count == 3
                };
            result[ri][ci] = new_val;
        }
    }
    result
}

fn matrix_count_cell_neighbors(matrix: Matrix, ri: i32, ci: i32) -> i32 {
    let mut count = 0;
    let offsets = [
        (-1, -1), (-1, 0), (-1, 1),
        (0, -1) ,          (0, 1),
        (1, -1) , (1, 0) , (1, 1)
    ];
    for offset in offsets.iter() {
        let &(ro, co) = offset;
        let r = ri + ro;
        let c = ci + co;
        if r < 0 || c < 0 || r >= HEIGH as i32 || c >= WIDTH as i32 {
            continue;
        } else if matrix[r as usize][c as usize] {
            count += 1;
        }
    }
    count
}


fn main() {
    let mut matrix = matrix_init();

    loop {
        print!("\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n");
        matrix_render(matrix);
        matrix = matrix_next(matrix);
        std::thread::sleep_ms(100);
    }
}