Using bsearch to find index for inserting new element into sorted array

Question

I have a sorted unique array and want to efficiently insert an element into it that is not in the array like this:

a = [1,2,4,5,6]
new_elm = 3
insert_at = a.bsearch_index {|x| x > new_elm } # => 2
a.insert(insert_at, new_elm) # now a = [1,2,3,4,5,6]

The method bsearch_index doesn't exist: only bsearch, which returns the matching element rather than the matching element's index. Is there any built in way to accomplish this?

Answer 1

Ruby 2.3.1 introduced bsearch_index thus the question can now be resolved this way:

a = [1,2,4,5,6]
new_elm = 3

index = a.bsearch_index{|x, _| x > new_elm}
=> 2

a.insert(index, new_elm)