Class: Cache::LinkedList

Inherits:
Object
  • Object
show all
Defined in:
lib/background_queue/server_lib/lru.rb

Defined Under Namespace

Classes: Element

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ LinkedList

Returns a new instance of LinkedList.



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# File 'lib/background_queue/server_lib/lru.rb', line 124

def initialize
  @head = @last = nil
end

Instance Attribute Details

#last ⇒ Object (readonly)

Returns the value of attribute last.



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# File 'lib/background_queue/server_lib/lru.rb', line 123

def last
  @last
end

Instance Method Details

#add(key, value) ⇒ Object 



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# File 'lib/background_queue/server_lib/lru.rb', line 128

def add(key, value)
  add_element(Element.new(key, value, @head))
end

#add_element(el) ⇒ Object 



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# File 'lib/background_queue/server_lib/lru.rb', line 132

def add_element(el)
  @head.previous_element = el if @head

  el.next_element = @head
  el.previous_element = nil
  @head = el
  @last = el unless @last
  el
end

#move_to_head(el) ⇒ Object 



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# File 'lib/background_queue/server_lib/lru.rb', line 150

def move_to_head(el)
  remove_element(el)
  add_element(el)
end

#pp ⇒ Object

Returns a nicely formatted stirng of all elements in the linked list. First element is most recently used, last element is least recently used.



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# File 'lib/background_queue/server_lib/lru.rb', line 158

def pp
  s = ''
  el = @head
  while el
    s << ', ' if s.size > 0
    s <<  el.to_s
    el = el.next_element
  end
  s
end

#remove_element(el) ⇒ Object 



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# File 'lib/background_queue/server_lib/lru.rb', line 142

def remove_element(el)
  el.previous_element.next_element = el.next_element if el.previous_element
  el.next_element.previous_element = el.previous_element if el.next_element

  @last = el.previous_element if el == @last
  @head = el.next_element if el == @head
end