C++17 STL Cookbook

How it works...

Initially, the gather algorithm is hard to grasp because it is very short but has a seemingly complex task. Therefore, let's step through it:

1. The initial state is a range of items, for which we present a predicate function. In the diagram, all items for which our predicate function returns true, are painted in gray. The iterators a and c mark the whole range, and iterator b points to a pivot element. The pivot element is the element around which we want to gather all the gray items.
2. The gather algorithm calls std::stable_partition on the range [a, b) and while doing that, it uses a negated version of the predicate. It negates ...