Make `Iterators.mergeSorted()` stable

I’ve noticed that Iterators.mergeSorted() is unstable.

So for example if I have arrays: [A_1, B_1, C_1] [A_2, B_2, C_2] (where the comparator looks only at the letter), I’d like the result to iterate [A_1, A_2, B_1, B_2, C_1, C_2]. The current implementation doesn’t guarantee this.

Might it be possible to add a stable version?

I confess it’s not obvious what to do if the arrays are something like [A_1, A_2, B_1], [A_3] - to me it would make sense to empty the first iterator of A_n elements before moving on to the second, so [A_1, A_2, A_3, B_1].

[I appreciate I’m being a little lazy with my terminology here - I can provide a fully fleshed example if it’s not clear]

[u6885077]

Hi, I am new to open source contribution projects. I see that this issue is still open. I was hoping that I could work on it if it has not already been implemented?

[msmerc]

@chaoren / google folk: I’ve had a go at solving this, see https://gist.github.com/msmerc/fff91f4049dd4d8e39f3614bb0c58acb

My solution is to generate a comparable such that objects are equal (using the original comparator) it will compare the position in the initial array. Is this something you’d want in the main library? Let me know.