programming-examples/ruby/Data_Structures/queue_as_array.rb
2019-11-15 12:59:38 +01:00

55 lines
1.0 KiB
Ruby

# This file contains the Ruby code from book of
# "Data Structures and Algorithms
# with Object-Oriented Design Patterns in Ruby"
# by Bruno R. Preiss.
#
# Copyright (c) 2004 by Bruno R. Preiss, P.Eng. All rights reserved.
class QueueAsArray < Queue
def initialize(size = 0)
super()
@array = Array.new(size)
@head = 0
@tail = size - 1
end
def purge
while @count > 0
@array[@head] = nil
@head = @head + 1
if @head == @array.length
@head = 0
end
@count -= 1
end
end
def head
raise ContainerEmpty if @count == 0
@array[@head]
end
def enqueue(obj)
raise ContainerFull if @count == @array.length
@tail = @tail + 1
if @tail == @array.length
@tail = 0
end
@array[@tail] = obj
@count += 1
end
def dequeue
raise ContainerEmpty if @count == 0
result = @array[@head]
@array[@head] = nil
@head = @head + 1
if @head == @array.length
@head = 0
end
@count -= 1
result
end
end