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use std::ops::{Bound, Range, RangeBounds};
/// Divide `n` by `divisor`, and round up to the nearest integer
/// if not evenly divisible.
#[inline]
pub(super) fn div_round_up(n: usize, divisor: usize) -> usize {
debug_assert!(divisor != 0, "Division by zero!");
if n == 0 {
0
} else {
(n - 1) / divisor + 1
}
}
/// Normalize arbitrary `RangeBounds` to a `Range`
pub(super) fn simplify_range(range: impl RangeBounds<usize>, len: usize) -> Range<usize> {
let start = match range.start_bound() {
Bound::Unbounded => 0,
Bound::Included(&i) if i <= len => i,
Bound::Excluded(&i) if i < len => i + 1,
bound => panic!("range start {:?} should be <= length {}", bound, len),
};
let end = match range.end_bound() {
Bound::Unbounded => len,
Bound::Excluded(&i) if i <= len => i,
Bound::Included(&i) if i < len => i + 1,
bound => panic!("range end {:?} should be <= length {}", bound, len),
};
if start > end {
panic!(
"range start {:?} should be <= range end {:?}",
range.start_bound(),
range.end_bound()
);
}
start..end
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn check_div_round_up() {
assert_eq!(0, div_round_up(0, 5));
assert_eq!(1, div_round_up(5, 5));
assert_eq!(1, div_round_up(1, 5));
assert_eq!(2, div_round_up(3, 2));
assert_eq!(
usize::max_value() / 2 + 1,
div_round_up(usize::max_value(), 2)
);
}
}