RFR: 8266571: Sequenced Collections [v12]

[Pavel Rappo]

On Fri, 21 Jul 2023 11:16:11 GMT, Hollis Waite <duke at openjdk.org> wrote:

>> Stuart Marks has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 96 commits:
>> 
>>  - Merge branch 'master' into JDK-8266571-SequencedCollections
>>  - Optimizations for ReverseOrderListView; check indexes in reversed domain.
>>  - Wording tweaks to SequencedMap / NavigableMap.
>>  - Change "The implementation in this class" to "... interface."
>>  - Delegate more methods in the views of ReverseOrderSortedMapView.
>>  - Add missing @throws and @since tags.
>>  - Convert code samples to snippets.
>>  - Various editorial changes.
>>  - Fix up toArray(T[]) on reverse-ordered views.
>>  - Remove unnecessary 'final' from a couple places.
>>  - ... and 86 more: https://git.openjdk.org/jdk/compare/2ea62c13...2827aa69
>
> It'd be convenient if SequencedCollection overrode Iterable.iterator() to return a ListIterator. That would make it simpler to derive a List from LinkedHashMap.values().

> @hwaite, the problem is that the derived List will not be a random access List, so it will perform badly with any code that loop over List.get() (yes, you are not supposed to do that but sadly a lot of people do).

Pardon? What about semantics mismatch and compatibility issues? If SequencedCollection were to redefine `iterator` as follows, it would break all the existing implementations of List out there:

    @Override
    ListIterator<E> iterator();

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PR Comment: https://git.openjdk.org/jdk/pull/7387#issuecomment-1645667941