I'm happy with the logic and specification of this proposal. I think it will be a useful addition.
I'll let the Oracle team chime in to do a further review. thanks Stephen On 16 January 2016 at 13:31, Tagir F. Valeev <amae...@gmail.com> wrote: > Hello! > > Thanks for review! Here's the updated patch: > http://cr.openjdk.java.net/~tvaleev/webrev/8146218/r2/ > > SC> The docs say that if the end date is before the start date, the > SC> stream is empty. While I can see just about why LongStream.range() > SC> works that way, I don't think this API should. The minimum is an > SC> exception, but it would be easy to support negative in the > SC> days-only case or the months-only case. The problem is where there > SC> are both months/years and days and those should be exceptions. > > Now datesUntil(endExclusive) throws an IllegalArgumentException if end > date is before start date. > > datesUntil(endExclusive, step) supports negative periods. It throws > IllegalArgumentException if: > - step is zero > - step.toTotalMonths() and step.getDays() both non-zero and have > opposite sign > - step is negative and end date is after start date > - step is positive and end date is before start date > > Otherwise it works correctly: you can use > LocalDate.of(2016, 1, 1) > .datesUntil(LocalDate.of(2015, 1, 1), Period.ofMonths(-1)); > > Steps like Period.of(-1, -1, -1) are also supported. > > SC> The single-arg implementation uses plusDays() with an > SC> incrementing number. When the performance patch goes in, the > SC> proposed streaming implementation will be optimal for small > SC> streams but less optimal for large ones. The fastest way to loop > SC> over a list of dates would be to manually generate them by > SC> incrementing the day until it exceeds the length of month, and so > SC> on. However, this would be serial. > > As I understand, plusDays performance patch is already pushed. > > It's possible to write custom Spliterator which would use > previous.plusDays(1) in tryAdvance() and jump (via > LocalDate.of(startEpochDay+n)) in trySplit() if parallel processing is > requested. However this adds at least one additional class and more > complexity. I guess, such optimization can be considered later as > separate issue when API is stabilized. > > SC> As such, I think the best way to write this, taking account of > SC> how plusDays() is implemented, is as follows: > > SC> LongStream.range(start.toEpochDay(), > SC> end.toEpochDay()).mapToObj(LocalDate::ofEpochDay); > > Ok, now it's done this way. > > SC> In the period-based method, it would be best to capture the case > SC> where totalMonths == 0 and days > 0 and forward to another method > SC> that ignores months. That private method can share implementation > SC> with the public single-arg method (passing in 1). > > This case still more complex than one-day case as it requires division > and multiplication. Thus I'd keep these case separately. However I > simplified "months = 0" path using ofEpochDay, now it should be > faster. > > SC> The docs for the period-based method should specify the strategy > SC> that produces the results (in abstract terms). This needs to cover > SC> that the result is equivalent to always adding to the start period > SC> a multiple of the period. > > I added some clarifications, please check. > > SC> Some nits: > SC> I prefer to avoid @link in the first sentence. Just using 'stream' > would be sufficient. > > Done. > > SC> The first sentence should be a summary. In this case it probably has a > bit too much detail. > > Done. > > SC> The @return has 'values' on a new line when it could be on the same > line. > > I set now line length = 100 characters in my IDE. Is it ok? > > SC> If statements need braces. > > Done. > > With best regards, > Tagir Valeev. > >
