class Concurrent::Collection::NonConcurrentPriorityQueue
@!macro priority_queue
A queue collection in which the elements are sorted based on their comparison (spaceship) operator `<=>`. Items are added to the queue at a position relative to their priority. On removal the element with the "highest" priority is removed. By default the sort order is from highest to lowest, but a lowest-to-highest sort order can be set on construction. The API is based on the `Queue` class from the Ruby standard library. The pure Ruby implementation, `RubyNonConcurrentPriorityQueue` uses a heap algorithm stored in an array. The algorithm is based on the work of Robert Sedgewick and Kevin Wayne. The JRuby native implementation is a thin wrapper around the standard library `java.util.NonConcurrentPriorityQueue`. When running under JRuby the class `NonConcurrentPriorityQueue` extends `JavaNonConcurrentPriorityQueue`. When running under all other interpreters it extends `RubyNonConcurrentPriorityQueue`. @note This implementation is *not* thread safe. @see http://en.wikipedia.org/wiki/Priority_queue @see http://ruby-doc.org/stdlib-2.0.0/libdoc/thread/rdoc/Queue.html @see http://algs4.cs.princeton.edu/24pq/index.php#2.6 @see http://algs4.cs.princeton.edu/24pq/MaxPQ.java.html @see http://docs.oracle.com/javase/7/docs/api/java/util/PriorityQueue.html
@!visibility private