wiki/list-editor/util.js

function reverse(a, from, to) {
    --from;
    while (++from < --to) {
        var tmp = a[from];
        a[from] = a[to];
        a[to] = tmp;
    }
}

function rotate(a, from, to, k) {
    var n = to - from;
    k = (k % n + n) % n;
    if (k > 0) {
        reverse(a, from, from + k);
        reverse(a, from + k, to);
        reverse(a, from, to);
    }
}

export default {
    rotate
};