Function intersection_by_custom

rust/stringzilla.rs:3771–3822

()

    #[test]
    fn intersection_by_custom() {
        // Define a custom type.
        #[derive(Debug)]
        #[allow(dead_code)]
        struct Person {
            name: &'static str,
            age: u32, //? We won't use this field for intersection
        }

        let group1 = [
            Person { name: "Alice", age: 25 },
            Person { name: "Bob", age: 30 },
            Person {
                name: "Charlie",
                age: 35,
            },
        ];
        let group2 = [
            Person { name: "David", age: 40 },
            Person {
                name: "Charlie",
                age: 50,
            },
            Person { name: "Alice", age: 60 },
        ];
        let mut out1 = [0; 3];
        let mut out2 = [0; 3];

        let n = sz::intersection_by(
            |i: sz::SortedIdx| group1[i].name.as_bytes(),
            |j: sz::SortedIdx| group2[j].name.as_bytes(),
            0,
            &mut out1,
            &mut out2,
        )
        .expect("intersection_by failed");
        assert!(n <= group1.len().min(group2.len()));

        // Use the indices for `group1` to get common names.
        let common_from_api: HashSet<_> = out1[..n].iter().map(|&i| group1[i].name).collect();

        // Compute expected common names using a `HashSet`.
        let expected: HashSet<_> = group1
            .iter()
            .map(|p| p.name)
            .collect::<HashSet<_>>()
            .intersection(&group2.iter().map(|p| p.name).collect())
            .cloned()
            .collect();

        assert_eq!(common_from_api, expected);
    }

    #[test]
    #[should_panic]