pub struct Indexer {
min_free_index: usize,
free_indices: Vec<usize>,
}
const RESERVATION_AMOUNT: isize = 10;
impl Indexer {
pub fn new() -> Self {
Indexer {
min_free_index: 0,
free_indices: Vec::new(),
}
}
pub fn free_index(&mut self, value: usize) {
self.free_indices.push(value);
}
pub fn get_next_index(&mut self) -> usize {
if self.free_indices.len() <= 0 {
self.reserve_indices(RESERVATION_AMOUNT);
}
self.free_indices.pop().unwrap()
}
fn get_next_min_index(&mut self) -> usize {
let result = self.min_free_index;
self.min_free_index += 1;
result
}
fn reserve_indices(&mut self, value: isize) {
let indices_to_reserve = (self.free_indices.len() as isize) - value;
let indices_to_reserve = if indices_to_reserve <= 0 { 0 } else { indices_to_reserve };
for _ in 0..indices_to_reserve {
let next_index = self.get_next_min_index();
self.free_indices.push(next_index);
}
}
}