default random access list spliterator
Peter Levart
peter.levart at gmail.com
Mon Mar 7 14:53:10 UTC 2016
On 03/07/2016 01:59 PM, Paul Sandoz wrote:
>> On 7 Mar 2016, at 12:47, Peter Levart <peter.levart at gmail.com> wrote:
>>
>> What about a Spliterator based on List.subList() method? While the specification of List.subList() does not guarantee any specific behavior when underlying list is structurally modified, the implementations (at least implementations in JDK based on AbstractList) do have a fail-fast behavior and there's a chance other implementations too.
>>
> We currently have as the @implSpec:
>
> * @implSpec
> * The default implementation creates a
> * <em><a href="Spliterator.html#binding">late-binding</a></em> spliterator
> * from the list's {@code Iterator}. The spliterator inherits the
> * <em>fail-fast</em> properties of the list's iterator.
>
> Note the inheritance clause, which also covers the sublist case.
>
> We would need to update with something like:
>
> "If this list implements RandomAccess then…. and the spliterator is late-binding, and fail-fast
> on a best effort basis if it is detected that this list (or any backing list if this list is a sub-list) has
> been structurally modified when traversing due to an change in size as returned by the size()
> method."
>
> Paul.
Hi Paul,
I don't think you understood my hint. I was thinking of a Spliterator
implementation for RandomAccess List(s) that would leverage
List.subList() method to implement splitting and/or fail-fast behavior.
As there is a good chance that sub-list implementations already provide
fail-fast behavior for structural changes in the backing list. For example:
Spliterator<E> spliterator() {
List<E> subList = subList(0, size());
return
IntStream.range(0,subList.size()).mapToObj(subList::get).spliterator();
}
This is a simple variant of Tagir's eager-binding RandomAccess
spliterator which is fail-fast if the List's sub-list is fail-fast.
Regards, Peter
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