Limit operation

[Brian Goetz]

Pushed.

On 9/17/2012 5:16 AM, Paul Sandoz wrote:
> Hi,
>
> Please see here for a simple implementation of the limit operation:
>
>    http://cr.openjdk.java.net/~psandoz/lambda/limit/webrev/
>
> Can someone with committer rights commit it?
>
> --
>
> This is the first intermediate type of operation that is short-circuiting. So it fills up a little gap in the use-cases.
>
> Other potential intermediate short-circuit operations are interleave and zipmap.
>
> This operation can be used in conjunction with a skip operation to produce a sub-stream and with streams of infinite size to limit the output to a finite size. Webrevs for those will appear in the very near future...
>
> It is a stateful operation, so will end up slicing the pipeline for the parallel case. Currently uses a very dumb serial impl that buffers items until the limit is reached, which is bad when the limit is large. A spliterator-based parallel implementation has similarities to some of the terminal find* operations, so i will look at what Brian's is doing for those and copy where appropriate!
>
> --
>
> I tweaked the exerciseOps code to not test sink wrapping for short-circuit ops, since it is currently not possible to short-circuit when pushing.
>
> I also look the liberty of cleaning up a bit the Iterator<Mapping<K, V> to MapIterator<K, V> code.
>
> Paul.
>