programming-examples/ruby/Data_Structures/hash_table.rb

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2019-11-15 12:59:38 +01:00
# 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 HashTable < SearchableContainer
def initialize
super
end
abstractmethod :length
def loadFactor
return count / length
end
def f(obj)
obj.hash
end
def g(x)
x.abs % length
end
def h(obj)
g(f(obj))
end
end
class ChainedHashTable < HashTable
def initialize(length)
super()
@array = Array.new(length)
for i in 0 ... length
@array[i] = SinglyLinkedList.new
end
end
def length
@array.length
end
def purge
for i in 0 ... length
@array[i].purge
end
@count = 0
end
def insert(obj)
@array[h(obj)].append(obj)
@count += 1
end
def withdraw(obj)
@array[h(obj)].extract(obj)
@count -= 1
end
def find(obj)
ptr = @array[h(obj)].head
while not ptr.nil?
return ptr.datum if ptr.datum == obj
ptr = ptr.succ
end
nil
end
end