Does Ruby have containers like stacks, queues, linked-lists, maps, or sets?

Question

I checked several Ruby tutorials online and they seemed to use array for everything. So how could I implement the following data structures in Ruby?

• Stacks
• Queues
• Linked lists
• Maps
• Sets

Answer 1

(Moved from Comment)

Well, an array can be a stack or queue by limiting yourself to stack or queue methods (push, pop, shift, unshift). Using push / pop gives LIFO(last in first out) behavior (stack), while using push / shift or unshift / pop gives FIFO behavior (queue).

Maps are hashes, and a Set class already exists.

You could implement a linked list using classes, but arrays will give linked-list like behavior using the standard array methods.

Answer 2

I guess most of it is covered in above answers but just for summing it up for a better explanation:

Stack:

stack = [] stack << 2 # push 2 => stack = [2] stack << 3 # push 3 => stack = [2, 3] stack.pop  # pop => 3, stack = [2] 

Queue:

# we have a Queue class queue = Queue.new queue << 2 # push 2 => queue = [2] queue << 3 # push 3 => queue = [2, 3] (just a representation, it will be an object though) queue.pop # pop 2 

Linked List:

# A very simple representation class Node   attr_accessor :value, :next_node    def initialize(value, next_node=nil)     @value = value     @next_node = next_node   end end  class LinkedList    def initialize(value)     @head = Node.new(value)   end    def add(value)     current = @head     while !current.next_node.nil?       current = current.next_node     end     current.next_node = Node.new(value)   end end  ll = LinkedList.new ll.add(10) ll.add(20) 

Maps:

# Hash incase of ruby a = {} (or a = Hash.new) a['one'] = 1 # a = {"one"=>1} a['two'] = 2 # a = {"one"=>1, "two"=>2} 

Set:

# we have a Set class require 'set' s = Set.new         # <Set: {}> s.add(1)            # <Set: {1}> s.add(2)            # <Set: {1, 2}> s.add(1)            # <Set: {1, 2}> s.instance_of?(Set) # true