btree_set_range/
btree_set_range.rs

1use std::collections::BTreeSet;
2use std::ops::Bound::{self, *};
3
4use quickcheck::{quickcheck, TestResult};
5
6/// Covers every `std::ops::Range*` plus variants with exclusive start.
7type RangeAny<T> = (Bound<T>, Bound<T>);
8
9/// Mimic `RangeBounds::contains`, stabilized in Rust 1.35.
10trait RangeBounds<T> {
11    fn contains(&self, _: &T) -> bool;
12}
13
14impl<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.
31fn 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`.
42fn 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
53fn main() {
54    quickcheck(check_range as fn(_, _) -> TestResult);
55}
btree_set_range/btree_set_range.rs

btree_set_range/
btree_set_range.rs
