Class: Hyperactive::List::Head

Inherits:
Record::Bass show all
Includes:
Archipelago::Current::ThreadedCollection
Defined in:
lib/hyperactive/list.rb

Overview

A List head.

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Transactions::Accessors

append_features

Methods included from Index::Indexable

append_features

Methods included from Record::Persistent

#<=>, append_features, #create, #with_transaction

Constructor Details

#initialize ⇒ Head

Create a List::Head. This is in essence the linked list.

NB: Remember to call create on the new instance or use Head.get_instance to get that done automatically.



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

def initialize
  super
  self.size = 0
  self.first_element = self.last_element = nil
end

Instance Attribute Details

#first_element ⇒ Object

Returns the value of attribute first_element.



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# File 'lib/hyperactive/list.rb', line 66

def first_element
  @first_element
end

#last_element ⇒ Object

Returns the value of attribute last_element.



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# File 'lib/hyperactive/list.rb', line 66

def last_element
  @last_element
end

#size ⇒ Object

Returns the value of attribute size.



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# File 'lib/hyperactive/list.rb', line 66

def size
  @size
end

Instance Method Details

#<<(v) ⇒ Object

Push v onto the end of this list.



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# File 'lib/hyperactive/list.rb', line 157

def <<(v)
  if self.first_element
    new_element = Element.get_instance_with_transaction(@transaction, self.last_element, nil, v, @record_id)
    self.last_element.next = new_element
    self.last_element = new_element
  else
    start(v)
  end
  self.size += 1
  return v
end

#clear! ⇒ Object

Remove all elements from this List::Head.



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# File 'lib/hyperactive/list.rb', line 117

def clear!
  self.first_element.t_each do |element|
    element.destroy!
  end
  self.first_element = self.last_element = nil
  self.size = 0
end

#destroy! ⇒ Object

Destroys this list and all its elements.



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# File 'lib/hyperactive/list.rb', line 128

def destroy!
  self.clear!
  super
end

#each(&block) ⇒ Object

Yield to block once for each value in this list.



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# File 'lib/hyperactive/list.rb', line 207

def each(&block)
  element = self.first_element
  while element
    yield(element.value)
    element = element.next
  end
end

#empty? ⇒ Boolean

Return whether this List is empty.

Returns:

  • (Boolean) 


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# File 'lib/hyperactive/list.rb', line 110

def empty?
  return self.size == 0
end

#first ⇒ Object

Return the first value of the list.



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# File 'lib/hyperactive/list.rb', line 136

def first
  if self.first_element
    self.first_element.value
  else
    nil
  end
end

#last ⇒ Object

Return the last value of the list.



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# File 'lib/hyperactive/list.rb', line 147

def last
  if self.last_element
    self.last_element.value
  else
  end
end

#pop ⇒ Object

Remove the last value from this list and return it.



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# File 'lib/hyperactive/list.rb', line 187

def pop
  v = nil
  if size > 1
    element = self.last_element
    self.last_element = element.previous
    self.last_element.next = nil
    v = element.value
    element.destroy!
  else
    v = self.first_element.value
    self.first_element.destroy!
    self.first_element = self.last_element = nil
  end
  self.size -= 1
  return v
end

#shift ⇒ Object

Remove the first value from this list and return it.



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# File 'lib/hyperactive/list.rb', line 218

def shift
  v = nil
  if size > 1
    element = self.first_element
    self.first_element = element.next
    self.first_element.previous = nil
    v = element.value
    element.destroy!
  else
    v = self.first_element.value
    self.first_element.destroy!
    self.first_element = self.last_element = nil
  end
  self.size -= 1
  return v
end

#unlink!(element) ⇒ Object

Unlinks the given element and reconnects the List around it.



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

def unlink!(element)
  raise "#{element} is not a part of #{self}" unless element.list_id == @record_id

  if size > 1
    if element == self.first_element
      self.first_element = element.next
      self.first_element.previous = nil
    elsif element == self.last_element
      self.last_element = element.previous
      self.last_element.next = nil
    else
      element.previous.next = element.next
      element.next.previous = element.previous
    end
  else
    if element == self.first_element
      self.first_element = self.last_element = nil
    else
      raise "#{element} is not a part of #{self} even though it claims to be"
    end
  end
  self.size -= 1
  element.destroy!
end

#unshift(v) ⇒ Object

Push v onto the beginning of this list.



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# File 'lib/hyperactive/list.rb', line 172

def unshift(v)
  if self.first_element
    new_element = Element.get_instance_with_transaction(@transaction, nil, self.first_element, v, @record_id)
    self.first_element.previous = new_element
    self.first_element = new_element
  else
    start(v)
  end 
  self.size += 1
  return v
end