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Diffstat (limited to 'vendor/rustc-rayon/src/math.rs')
-rw-r--r-- | vendor/rustc-rayon/src/math.rs | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/vendor/rustc-rayon/src/math.rs b/vendor/rustc-rayon/src/math.rs new file mode 100644 index 000000000..9de588965 --- /dev/null +++ b/vendor/rustc-rayon/src/math.rs @@ -0,0 +1,54 @@ +use std::ops::{Bound, Range, RangeBounds}; + +/// Divide `n` by `divisor`, and round up to the nearest integer +/// if not evenly divisable. +#[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) + ); + } +} |