rbtree-ruby

https://github.com/firelzrd/rbtree-ruby

A high-performance pure Ruby Red-Black Tree implementation. Features: O(1) key lookup via hybrid hash index, O(log n) insert/delete, lazy Enumerator-based range queries (lt/gt/between), nearest/prev/succ search, memory-efficient node pooling, and MultiRBTree for duplicate keys with first/last value access.