GoLLRB

GoLLRB is a Left-Leaning Red-Black (LLRB) implementation of 2-3 balanced binary search trees in Go Language.

Overview

As of this writing and to the best of the author's knowledge, Go still does not have a balanced binary search tree (BBST) data structure. These data structures are quite useful in a variety of cases. A BBST maintains elements in sorted order under dynamic updates (inserts and deletes) and can support various order-specific queries. Furthermore, in practice one often implements other common data structures like Priority Queues, using BBST's.

2-3 trees (a type of BBST's), as well as the runtime-similar 2-3-4 trees, are the de facto standard BBST algoritms found in implementations of Python, Java, and other libraries. The LLRB method of implementing 2-3 trees is a recent improvement over the traditional implementation. The LLRB approach was discovered relatively recently (in 2008) by Robert Sedgewick of Princeton University.

GoLLRB is a Go implementation of LLRB 2-3 trees.

Maturity

GoLLRB has been used in some pretty heavy-weight machine learning tasks over many gigabytes of data. I consider it to be in stable, perhaps even production, shape. There are no known bugs.

Installation

With a healthy Go Language installed, simply run go get github.com/petar/GoLLRB/llrb

Example

package main

import (
	"fmt"
	"github.com/petar/GoLLRB/llrb"
)

func Print(item llrb.Item) bool {
	i, ok := item.(llrb.Int)
	if !ok {
		return false
	}
	fmt.Println(int(i))
	return true
}

func main() {
	tree := llrb.New()
	tree.ReplaceOrInsert(llrb.Int(1))
	tree.ReplaceOrInsert(llrb.Int(2))
	tree.ReplaceOrInsert(llrb.Int(3))
	tree.ReplaceOrInsert(llrb.Int(4))
	tree.DeleteMin()
	tree.Delete(llrb.Int(4))
	tree.AscendGreaterOrEqual(tree.Min(), Print)
}

About

GoLLRB was written by Petar Maymounkov.

Follow me on Twitter @maymounkov!