cuendillar 0.1.0

Embedded persistent key–value storage engine (LSM-tree based)
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

use std::cmp::Ordering;

use crate::database::iterator::DatabaseIterator;

impl PartialEq for Box<dyn DatabaseIterator> {
    fn eq(&self, other: &Self) -> bool {
        self.peek() == other.peek()
    }
}

impl Eq for Box<dyn DatabaseIterator> {}

impl PartialOrd for Box<dyn DatabaseIterator> {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl Ord for Box<dyn DatabaseIterator> {
    fn cmp(&self, other: &Self) -> Ordering {
        match (self.peek(), other.peek()) {
            (Some(a), Some(b)) => {
                if a.get_key() < b.get_key() {
                    Ordering::Greater
                } else if a.get_key() > b.get_key() {
                    Ordering::Less
                }
                // if above two conditions are false then they two are equal
                else if a.get_seq_no() > b.get_seq_no() {
                    Ordering::Greater
                } else {
                    Ordering::Less
                }
            } // reverse for min-heap behavior
            (Some(_), None) => Ordering::Less,
            (None, Some(_)) => Ordering::Greater,
            (None, None) => Ordering::Equal,
        }
    }
}