lsm_tree/
util.rs

1use crate::range::prefix_upper_range;
2use crate::UserKey;
3use std::ops::RangeBounds;
4
5pub use crate::range::prefix_to_range;
6
7/// Helper function to create a prefixed range.
8///
9/// Made for phil.
10///
11/// # Panics
12///
13/// Panics if the prefix is empty.
14pub fn prefixed_range<P: AsRef<[u8]>, K: AsRef<[u8]>, R: RangeBounds<K>>(
15    prefix: P,
16    range: R,
17) -> impl RangeBounds<UserKey> {
18    use std::ops::Bound::{Excluded, Included, Unbounded};
19
20    let prefix = prefix.as_ref();
21
22    assert!(!prefix.is_empty(), "prefix may not be empty");
23
24    match (range.start_bound(), range.end_bound()) {
25        (Unbounded, Unbounded) => prefix_to_range(prefix),
26        (lower, Unbounded) => {
27            let lower = lower.map(|k| UserKey::fused(prefix, k.as_ref()));
28            let upper = prefix_upper_range(prefix);
29            (lower, upper)
30        }
31        (Unbounded, upper) => {
32            let upper = match upper {
33                Included(k) => Included(UserKey::fused(prefix, k.as_ref())),
34                Excluded(k) => Excluded(UserKey::fused(prefix, k.as_ref())),
35                Unbounded => unreachable!(),
36            };
37
38            (Included(prefix.into()), upper)
39        }
40        (lower, upper) => {
41            let lower = match lower {
42                Included(k) => Included(UserKey::fused(prefix, k.as_ref())),
43                Excluded(k) => Excluded(UserKey::fused(prefix, k.as_ref())),
44                Unbounded => unreachable!(),
45            };
46
47            let upper = match upper {
48                Included(k) => Included(UserKey::fused(prefix, k.as_ref())),
49                Excluded(k) => Excluded(UserKey::fused(prefix, k.as_ref())),
50                Unbounded => unreachable!(),
51            };
52
53            (lower, upper)
54        }
55    }
56}
57
58#[cfg(test)]
59mod tests {
60    use super::prefixed_range;
61    use crate::UserKey;
62    use std::ops::Bound::{Excluded, Included};
63    use std::ops::RangeBounds;
64    use test_log::test;
65
66    #[test]
67    fn prefixed_range_1() {
68        let prefix = "abc";
69        let min = 5u8.to_be_bytes();
70        let max = 9u8.to_be_bytes();
71
72        let range = prefixed_range(prefix, min..=max);
73
74        assert_eq!(
75            range.start_bound(),
76            Included(&UserKey::new(&[b'a', b'b', b'c', 5]))
77        );
78        assert_eq!(
79            range.end_bound(),
80            Included(&UserKey::new(&[b'a', b'b', b'c', 9]))
81        );
82    }
83
84    #[test]
85    fn prefixed_range_2() {
86        let prefix = "abc";
87        let min = 5u8.to_be_bytes();
88        let max = 9u8.to_be_bytes();
89
90        let range = prefixed_range(prefix, min..max);
91
92        assert_eq!(
93            range.start_bound(),
94            Included(&UserKey::new(&[b'a', b'b', b'c', 5]))
95        );
96        assert_eq!(
97            range.end_bound(),
98            Excluded(&UserKey::new(&[b'a', b'b', b'c', 9]))
99        );
100    }
101
102    #[test]
103    fn prefixed_range_3() {
104        let prefix = "abc";
105        let min = 5u8.to_be_bytes();
106
107        let range = prefixed_range(prefix, min..);
108
109        assert_eq!(
110            range.start_bound(),
111            Included(&UserKey::new(&[b'a', b'b', b'c', 5]))
112        );
113        assert_eq!(range.end_bound(), Excluded(&UserKey::new(b"abd")));
114    }
115
116    #[test]
117    fn prefixed_range_4() {
118        let prefix = "abc";
119        let max = 9u8.to_be_bytes();
120
121        let range = prefixed_range(prefix, ..max);
122
123        assert_eq!(range.start_bound(), Included(&UserKey::new(b"abc")));
124        assert_eq!(
125            range.end_bound(),
126            Excluded(&UserKey::new(&[b'a', b'b', b'c', 9]))
127        );
128    }
129
130    #[test]
131    fn prefixed_range_5() {
132        let prefix = "abc";
133        let max = u8::MAX.to_be_bytes();
134
135        let range = prefixed_range(prefix, ..=max);
136
137        assert_eq!(range.start_bound(), Included(&UserKey::new(b"abc")));
138        assert_eq!(
139            range.end_bound(),
140            Included(&UserKey::new(&[b'a', b'b', b'c', u8::MAX]))
141        );
142    }
143
144    #[test]
145    fn prefixed_range_6() {
146        let prefix = "abc";
147        let max = u8::MAX.to_be_bytes();
148
149        let range = prefixed_range(prefix, ..max);
150
151        assert_eq!(range.start_bound(), Included(&UserKey::new(b"abc")));
152        assert_eq!(
153            range.end_bound(),
154            Excluded(&UserKey::new(&[b'a', b'b', b'c', u8::MAX]))
155        );
156    }
157}
lsm_tree/util.rs

lsm_tree/
util.rs
