> Sometimes, `Spliterator::forEachRemaining` has much more optimized > implementation, compared to `Spliterator::tryAdvance`. For example, if a > `Stream::spliterator` called for a stream that has intermediate operations, > `tryAdvance()` may buffer intermediate elements while `forEachRemaining()` > just delegates to the `wrapAndCopyInto` (see > `StreamSpliterators.AbstractWrappingSpliterator` and its inheritors). > > `Spliterators::iterator` methods (used in particular by `Stream::iterator`) > provide adapter iterators that delegate to the supplied spliterator. > Unfortunately, they don't have a specialized implementation for > `Iterator::forEachRemaining`. As a result, a default implementation is used > that delegates to `hasNext`/`next`, which in turn causes the delegation to > `tryAdvance`. It's quite simple to implement `Iterator::forEachRemaining` > here, taking advantage of possible spliterator optimizations if the iterator > client decides to use `forEachRemaining`. > > This patch implements Iterator::forEachRemaining in Spliterators::iterator > methods. Also, I nullize the `nextElement` in `Iterator::next` to avoid > accidental prolongation of the user's object lifetime when iteration is > finished. Finally, a small cleanup: I added the `final` modifier where > possible to private fields in `Spliterators`. > > Test-wise, some scenarios are already covered by > SpliteratorTraversingAndSplittingTest. However, the resulting iterator is > always wrapped into `Spliterators::spliterator`, so usage scenarios are > somewhat limited. In particular, calling `hasNext` (without `next`) before > `forEachRemaining` was not covered there. I added more tests in > `IteratorFromSpliteratorTest` to cover these scenarios. I checked that > removing `valueReady = false;` or `action.accept(t);` lines from newly > implemented `forEachRemaining` method causes new tests to fail (but old tests > don't fail due to this).
Tagir F. Valeev has updated the pull request incrementally with one additional commit since the last revision: Add a comment clarifying the purpose of the test ------------- Changes: - all: https://git.openjdk.java.net/jdk/pull/4124/files - new: https://git.openjdk.java.net/jdk/pull/4124/files/9a5e0dd2..cc337995 Webrevs: - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4124&range=02 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4124&range=01-02 Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod Patch: https://git.openjdk.java.net/jdk/pull/4124.diff Fetch: git fetch https://git.openjdk.java.net/jdk pull/4124/head:pull/4124 PR: https://git.openjdk.java.net/jdk/pull/4124
