WIP: Iterable string splitting (splititr)

[ghost]

As per discussion in #6933, an iterator variant of split (and also possibly rsplit) would be useful.

[ghost]

This is still WIP, but it supports the basic functionality of split. It uses an immutable iterator object this time and keeps the state separate. Feedback is as always welcome.

• limit
• keep_empty
• run with the full split test suite

I also noticed that split and rsplit lacks Unicode tests, I should probably open a separate PR for this.

[ivarne]

I think this immutable would perform better if it was made parametric

immutable SplitItr{S<:String, T}
    str::S
    splitter::T
end

[ghost]

@ivarne: Thanks a bundle for the feedback, I have incorporated it into my local repository. I still intend to complete this PR and hope to be able to grab some time this weekend to, my apologies for causing additional messages to go out on the mailing list, do tell me if this was bad style on my part.

[ivarne]

It will be great to see this finished, especially if the performance could be good enough to implement split as.

split(...) = collect(splititr(...))

There are lots of posts in the Julia community, and as long as they are "on topic", it is fairly easy for everyone that follows the project to find out if they have anything to contribute on the topic. If you have a question or an opinion, feel free to post. Announcing that you might find time this weekend, is probably not that interesting for everyone to see (especially on a PR that has been silent for 12 days). It is unlikely that someone else will do the job in parallel with you, and because this is performance sensitive code, it will be good to have multiple implementations to test anyway.

[StefanKarpinski]

I don't mind the reminder, myself. But then, given the amount of Julia email I get, what's one more?

[vtjnash]

Seems like a good addition (sorry for the surprise; I'm looking at really old PR's today). Care to update this to look like the current Base._split method, and then define split(...) = collect(SubString{T}, splititr(...)) as suggested above?