Class: Containers::List

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

Defined Under Namespace

Classes: Node

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ List

Returns a new instance of List.



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# File 'lib/containers/list.rb', line 4

def initialize
  @first = nil
  @last = nil
end

Class Method Details

.[](*arr) ⇒ Object 



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# File 'lib/containers/list.rb', line 9

def self.[](*arr)
  from_a(arr)
end

.from_a(arr) ⇒ Object 



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

def self.from_a(arr)
  l = new
  arr.each(&l.method(:push_front))
  l
end

Instance Method Details

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/containers/list.rb', line 19

def empty?
  @first == @last && @first.nil?
end

#peek_back ⇒ Object 



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# File 'lib/containers/list.rb', line 73

def peek_back
  @last&.data
end

#peek_front ⇒ Object 



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# File 'lib/containers/list.rb', line 69

def peek_front
  @first&.data
end

#pop_back ⇒ Object Also known as: pop 



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# File 'lib/containers/list.rb', line 56

def pop_back
  to_return = @last&.data
  unless @last.nil?
    @last = @last.prev
    if @last.nil?
      @first = nil
    else
      @last.next = nil unless @last.nil?
    end
  end
  to_return
end

#pop_front ⇒ Object Also known as: shift 



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# File 'lib/containers/list.rb', line 33

def pop_front
  to_return = @first&.data
  unless @first.nil?
    @first = @first.next
    if @first.nil?
      @last = nil
    else
      @first.prev = nil unless @first.nil?
    end
  end
  to_return
end

#push_back(element) ⇒ Object Also known as: push 



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

def push_back(element)
  node = Node.new(element, @last, nil)
  if @last.nil?
    @first = node
  else
    @last.next = node
  end
  @last = node
end

#push_front(element) ⇒ Object Also known as: unshift 



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# File 'lib/containers/list.rb', line 23

def push_front(element)
  node = Node.new(element, nil, @first)
  if @first.nil?
    @last = node
  else
    @first.prev = node
  end
  @first = node
end