Class: Async::List

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

Overview

A general doublely linked list. This is used internally by Barrier and Condition to manage child tasks.

Direct Known Subclasses

Children

Defined Under Namespace

Classes: Node

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ List

Initialize a new, empty, list.



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# File 'lib/async/list.rb', line 10

def initialize
	@head = self
	@tail = self
	@size = 0
end

Instance Attribute Details

#head ⇒ Object

Points at the end of the list.



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# File 'lib/async/list.rb', line 40

def head
  @head
end

#size ⇒ Object (readonly)

Returns the value of attribute size.



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# File 'lib/async/list.rb', line 45

def size
  @size
end

#tail ⇒ Object

Points at the start of the list.



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# File 'lib/async/list.rb', line 43

def tail
  @tail
end

Instance Method Details

#added(node) ⇒ Object

A callback that is invoked when an item is added to the list.



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# File 'lib/async/list.rb', line 48

def added(node)
	@size += 1
	return node
end

#append(node) ⇒ Object

Append a node to the end of the list.



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# File 'lib/async/list.rb', line 54

def append(node)
	if node.head
		raise ArgumentError, "Node is already in a list!"
	end
	
	node.tail = self
	@head.tail = node
	node.head = @head
	@head = node
	
	return added(node)
end

#each(&block) ⇒ Object

Iterate over each node in the linked list. It is generally safe to remove the current node, any previous node or any future node during iteration.



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# File 'lib/async/list.rb', line 173

def each(&block)
	return to_enum unless block_given?
	
	Iterator.each(self, &block)
	
	return self
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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

def empty?
	@size == 0
end

#first ⇒ Object 



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# File 'lib/async/list.rb', line 194

def first
	# validate!
	
	current = @tail
	
	while !current.equal?(self)
		if current.is_a?(Iterator)
			current = current.tail
		else
			return current
		end
	end
	
	return nil
end

#include?(needle) ⇒ Boolean

Determine whether the given node is included in the list.

Returns:

  • (Boolean) 


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# File 'lib/async/list.rb', line 185

def include?(needle)
	self.each do |item|
		return true if needle.equal?(item)
	end
	
	return false
end

#last ⇒ Object 



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# File 'lib/async/list.rb', line 211

def last
	# validate!
	
	current = @head
	
	while !current.equal?(self)
		if current.is_a?(Iterator)
			current = current.head
		else
			return current
		end
	end
	
	return nil
end

#prepend(node) ⇒ Object 



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# File 'lib/async/list.rb', line 67

def prepend(node)
	if node.head
		raise ArgumentError, "Node is already in a list!"
	end
	
	node.head = self
	@tail.head = node
	node.tail = @tail
	@tail = node
	
	return added(node)
end

#remove(node) ⇒ Object

Remove the node. If it was already removed, this will raise an error.

You should be careful to only remove nodes that are part of this list.



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# File 'lib/async/list.rb', line 115

def remove(node)
	# One downside of this interface is we don't actually check if the node is part of the list defined by `self`. This means that there is a potential for a node to be removed from a different list using this method, which in can throw off book-keeping when lists track size, etc.
	unless node.head
		raise ArgumentError, "Node is not in a list!"
	end
	
	remove!(node)
end

#remove?(node) ⇒ Boolean

Remove the node if it is in a list.

You should be careful to only remove nodes that are part of this list.

Returns:

  • (Boolean) 


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# File 'lib/async/list.rb', line 101

def remove?(node)
	if node.head
		return remove!(node)
	end
	
	return nil
end

#removed(node) ⇒ Object

A callback that is invoked when an item is removed from the list.



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# File 'lib/async/list.rb', line 91

def removed(node)
	@size -= 1
	return node
end

#shift ⇒ Object 



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# File 'lib/async/list.rb', line 227

def shift
	if node = first
		remove!(node)
	end
end

#stack(node, &block) ⇒ Object

Add the node, yield, and the remove the node.



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# File 'lib/async/list.rb', line 83

def stack(node, &block)
	append(node)
	return yield(node)
ensure
	remove!(node)
end

#to_a ⇒ Object

Fast, safe, unbounded accumulation of children.



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# File 'lib/async/list.rb', line 24

def to_a
	items = []
	current = self
	
	while current.tail != self
		unless current.tail.is_a?(Iterator)
			items << current.tail
		end
		
		current = current.tail
	end
	
	return items
end

#to_s ⇒ Object Also known as: inspect

Print a short summary of the list.



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# File 'lib/async/list.rb', line 17

def to_s
	sprintf("#<%s:0x%x size=%d>", self.class.name, object_id, @size)
end