1use std::ops::{Bound, Range, RangeBounds};
2
3/// Divide `n` by `divisor`, and round up to the nearest integer
4/// if not evenly divisible.
5#[inline]
6pub(super) fn div_round_up(n: usize, divisor: usize) -> usize {
7 debug_assert!(divisor != 0, "Division by zero!");
8 if n == 0 {
9 0
10 } else {
11 (n - 1) / divisor + 1
12 }
13}
14
15/// Normalize arbitrary `RangeBounds` to a `Range`
16pub(super) fn simplify_range(range: impl RangeBounds<usize>, len: usize) -> Range<usize> {
17 let start: usize = match range.start_bound() {
18 Bound::Unbounded => 0,
19 Bound::Included(&i: usize) if i <= len => i,
20 Bound::Excluded(&i: usize) if i < len => i + 1,
21 bound: Bound<&usize> => panic!("range start {:?} should be <= length {}", bound, len),
22 };
23 let end: usize = match range.end_bound() {
24 Bound::Unbounded => len,
25 Bound::Excluded(&i: usize) if i <= len => i,
26 Bound::Included(&i: usize) if i < len => i + 1,
27 bound: Bound<&usize> => panic!("range end {:?} should be <= length {}", bound, len),
28 };
29 if start > end {
30 panic!(
31 "range start {:?} should be <= range end {:?}",
32 range.start_bound(),
33 range.end_bound()
34 );
35 }
36 start..end
37}
38
39#[cfg(test)]
40mod tests {
41 use super::*;
42
43 #[test]
44 fn check_div_round_up() {
45 assert_eq!(0, div_round_up(0, 5));
46 assert_eq!(1, div_round_up(5, 5));
47 assert_eq!(1, div_round_up(1, 5));
48 assert_eq!(2, div_round_up(3, 2));
49 assert_eq!(
50 usize::max_value() / 2 + 1,
51 div_round_up(usize::max_value(), 2)
52 );
53 }
54}
55