Grid Mutation Iterator

grid_neighbors_mut.rs

struct GridNeighborsMut<'a> {
  grid: &'a mut Grid,
  point_x: usize,
  point_y: usize,
  count: usize,
}
impl<'a> Iterator for GridNeighborsMut<'a> {
  type Item = &'a mut Elevation;
  fn next(&mut self) -> Option<Self::Item> {
      unsafe {
          let grid = self.grid;
          match self.count {
              0 => {
                  self.count += 1;
                  grid.get_mut(self.point_x, self.point_y + 1)
              }
              1 => {
                  self.count += 1;
                  grid.get_mut(self.point_x + 1, self.point_y)
              }
              2 => {
                  self.count += 1;
                  grid.get_mut(self.point_x, self.point_y - 1)
              }
              3 => {
                  self.count += 1;
                  grid.get_mut(self.point_x - 1, self.point_y)
              }
              _ => None,
          }
      }
  }
}