mergesorted - function to merge together 2 sorted iterators

[dfdx]

Function to merge 2 sorted iterators of unique values. Example:

it1 = [:a, :c, :d, :f]
it2 = [:b, :d, :e]
merged = mergesorted(it1, it2)
collect(merged)  # ==> [:a, :b, :c, :d, :e, :f]

(Note that :d presents in both iterators, but only single occurrence is emitted)

[tkelman]

are

[dfdx]

Fixed, thanks.

[dfdx]

I noticed that tests were failing for Julia 0.5, so I've rewritten them to be more similar to existing ones. I also modified next function to make it easier to analyze.

[mschauer]

We usually do not throw an error for calling next after done

[dfdx]

I don't really have a strong opinion here, but I'm curious what's the conventional approach to handle next() after done(...) == true?

I know that for objects like ranges we can just continue producing new elements. However, for IO-based iterators (e.g. iterator over a file) we can't really produce anything else after the end of EOF. So what is supposed to be an appropriate result for calls to next() for such iterators?

(In fact, I'm working on one such iterator right now, so would be glad to make it using best practices)

[mschauer]

The conventional approach is to assume that one only calls next after having called done before to make sure that the iterator is not terminated.

[dfdx]

Please, check #63 for a version of PR that takes into account some of comments in this thread.

[dfdx]

Closing as the least valuable implementation, see improved versions in #63