Today is more server side coding for algorithms straight from my thesis. There are some tweaks to the order of the algorithm for improved performance. I really want to get away with single data pass, but I need two steps: 

1) accumulate geometry in projection space.

2) iterated over projection space, presented in order.

This is a similar problem of finding the index of an item in a sorted list. 

< "forest", "sign", "deer", "road" >

A fast approach to finding the index for quick lookup time O(log n) requires sorting the list first. A lexicographical sort gives:

The index of the word "forest" is 1

To achieve this without sorting requires knowing all the preceding lower values. This is linear in search time, since a traversal through the entire list is needed to find out that there is one element less than "forest". Now to complicate the problem, what if it were a stream of data. It would be impossible to determine how many following items had value less than "forest" until they are seen. Halting problem.

EDIT: forgot to mention Xcode crashed only once today!