Class: List

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/list.rb

Overview

This class is used to represent double-linked lists It includes the mixin Enumerable

Defined Under Namespace

Classes: Node

Instance Method Summary collapse

Constructor Details

#initialize ⇒ List

initializes the vales of the list’s head and tail to nil



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# File 'lib/list.rb', line 13

def initialize

  @head = nil
  @tail = nil

end

Instance Method Details

#add(value) ⇒ Object

adds a value to the end of the list, behind the former last element if it’s the first element, this becomes the new head and tail



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# File 'lib/list.rb', line 31

def add (value)

  if @tail == nil then
    @head = Node.new(value, nil, nil)
    @tail = @head
  else
    temp = Node.new(value, nil, @tail)
    @tail.next = temp
    @tail = temp
  end

end

#addAll(array) ⇒ Object

adds all elements in the given Array to our list. This works by calling the add(value)-method for each element in the array



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# File 'lib/list.rb', line 46

def addAll (array)

  array.each { |value| add(value) }

end

#each ⇒ Object

this method is included because we implement the method Enumerable. Yields every element in the list, one after another, by calling the to_a-method.



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# File 'lib/list.rb', line 95

def each
  self.to_a.each { |i| yield i }
end

#getNode ⇒ Object

returns the head-node



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# File 'lib/list.rb', line 53

def getNode

  @head

end

#head ⇒ Object

returns the value of the head



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# File 'lib/list.rb', line 60

def head
  @head.value
end

#isEmpty? ⇒ Boolean

returns true if the list is empty and false else

Returns:

  • (Boolean) 


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# File 'lib/list.rb', line 21

def isEmpty?
  if @head == nil then
    true
  else
    false
  end
end

#tail ⇒ Object

returns the value of the tail



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# File 'lib/list.rb', line 65

def tail   
  @tail.value
end

#to_a ⇒ Object

returns an array with all the values of this list



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# File 'lib/list.rb', line 70

def to_a
  tempArray = []
  tempNode = @head
  while tempNode != nil do
    tempArray.push(tempNode.value)
    tempNode = tempNode.next
  end
  tempArray
end

#to_a_reverse ⇒ Object

returns an array with all the values of this list, but in a reverse order



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# File 'lib/list.rb', line 82

def to_a_reverse
  tempArray = []
  tempNode = @tail
  while tempNode != nil do
    tempArray.push(tempNode.value)
    tempNode = tempNode.prev
  end
  tempArray
end