Jeff Vander Stoep | aa840b6 | 2021-10-19 10:09:02 +0200 | [diff] [blame] | 1 | use std::collections::BTreeSet; |
| 2 | use std::ops::Bound::{self, *}; |
| 3 | |
| 4 | use quickcheck::{quickcheck, TestResult}; |
| 5 | |
| 6 | /// Covers every `std::ops::Range*` plus variants with exclusive start. |
| 7 | type RangeAny<T> = (Bound<T>, Bound<T>); |
| 8 | |
| 9 | /// Mimic `RangeBounds::contains`, stabilized in Rust 1.35. |
| 10 | trait RangeBounds<T> { |
| 11 | fn contains(&self, _: &T) -> bool; |
| 12 | } |
| 13 | |
| 14 | impl<T: PartialOrd> RangeBounds<T> for RangeAny<T> { |
| 15 | fn contains(&self, item: &T) -> bool { |
| 16 | (match &self.0 { |
| 17 | Included(start) => start <= item, |
| 18 | Excluded(start) => start < item, |
| 19 | Unbounded => true, |
| 20 | }) && (match &self.1 { |
| 21 | Included(end) => item <= end, |
| 22 | Excluded(end) => item < end, |
| 23 | Unbounded => true, |
| 24 | }) |
| 25 | } |
| 26 | } |
| 27 | |
| 28 | /// Checks conditions where `BTreeSet::range` panics: |
| 29 | /// - Panics if range start > end. |
| 30 | /// - Panics if range start == end and both bounds are Excluded. |
| 31 | fn panics<T: PartialOrd>(range: RangeAny<T>) -> bool { |
| 32 | match (&range.0, &range.1) { |
| 33 | (Excluded(start), Excluded(end)) => start >= end, |
| 34 | (Included(start), Excluded(end)) |
| 35 | | (Excluded(start), Included(end)) |
| 36 | | (Included(start), Included(end)) => start > end, |
| 37 | (Unbounded, _) | (_, Unbounded) => false, |
| 38 | } |
| 39 | } |
| 40 | |
| 41 | /// Checks that `BTreeSet::range` returns all items contained in the given `range`. |
| 42 | fn check_range(set: BTreeSet<i32>, range: RangeAny<i32>) -> TestResult { |
| 43 | if panics(range) { |
| 44 | TestResult::discard() |
| 45 | } else { |
| 46 | let xs: BTreeSet<_> = set.range(range).cloned().collect(); |
| 47 | TestResult::from_bool( |
| 48 | set.iter().all(|x| range.contains(x) == xs.contains(x)), |
| 49 | ) |
| 50 | } |
| 51 | } |
| 52 | |
| 53 | fn main() { |
| 54 | quickcheck(check_range as fn(_, _) -> TestResult); |
| 55 | } |