fn test_into_iter_refresh()

in sgx_tstd/hashbrown/src/map.rs [6285:6349]

• 57 lines of code
• 9 McCabe index (conditional complexity)

    fn test_into_iter_refresh() {
        #[cfg(miri)]
        const N: usize = 32;
        #[cfg(not(miri))]
        const N: usize = 128;

        let mut rng = rand::thread_rng();
        for n in 0..N {
            let mut map = HashMap::new();
            for i in 0..n {
                assert!(map.insert(i, 2 * i).is_none());
            }
            let hash_builder = map.hasher().clone();

            let mut it = unsafe { map.table.iter() };
            assert_eq!(it.len(), n);

            let mut i = 0;
            let mut left = n;
            let mut removed = Vec::new();
            loop {
                // occasionally remove some elements
                if i < n && rng.gen_bool(0.1) {
                    let hash_value = super::make_insert_hash(&hash_builder, &i);

                    unsafe {
                        let e = map.table.find(hash_value, |q| q.0.eq(&i));
                        if let Some(e) = e {
                            it.reflect_remove(&e);
                            let t = map.table.remove(e);
                            removed.push(t);
                            left -= 1;
                        } else {
                            assert!(removed.contains(&(i, 2 * i)), "{} not in {:?}", i, removed);
                            let e = map.table.insert(
                                hash_value,
                                (i, 2 * i),
                                super::make_hasher::<usize, _, usize, _>(&hash_builder),
                            );
                            it.reflect_insert(&e);
                            if let Some(p) = removed.iter().position(|e| e == &(i, 2 * i)) {
                                removed.swap_remove(p);
                            }
                            left += 1;
                        }
                    }
                }

                let e = it.next();
                if e.is_none() {
                    break;
                }
                assert!(i < n);
                let t = unsafe { e.unwrap().as_ref() };
                assert!(!removed.contains(t));
                let (key, value) = t;
                assert_eq!(*value, 2 * key);
                i += 1;
            }
            assert!(i <= n);

            // just for safety:
            assert_eq!(map.table.len(), left);
        }
    }