List<T> modification

A.md

Try Haxe

ListUtils.hx

class ListUtils {
  public static function kvIt<T>(list:List<T>):ListKeyItemIterator<T> {
    return new ListKeyItemIterator(@:privateAccess list.h);
  }
}

private typedef ListNode<T> = {item:T, next:ListNode<T>};

private class ListKeyItemIterator<T> {
  var idx:Int;
  var head:ListNode<T>;

  public inline function new(head:ListNode<T>) {
    this.head = head;
    this.idx = 0;
  }

  public inline function hasNext():Bool {
    return head != null;
  }

  public inline function next():{key:Int, value:ListNode<T>} {
    var val = head.item;
    var ret = {value: head, key: idx++};
    head = head.next;
    return ret;
  }
}

Test.hx

using ListUtils;

class Test {
  static function main() {
    var list = new List<Int>();
    for (i in 0...10) list.add(i);

    for (i => item in list.kvIt()) {
      if (i == 4) {
        item.item = 42;
        break;
      }
    }

    for (i in list) trace(i);
  }
}