Class: IntervalSkipList

Inherits:
Object
  • Object
show all
Defined in:
lib/treetop/runtime/interval_skip_list/node.rb,
lib/treetop/runtime/interval_skip_list/head_node.rb,
lib/treetop/runtime/interval_skip_list/interval_skip_list.rb

Defined Under Namespace

Classes: HeadNode, Node

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ IntervalSkipList

Returns a new instance of IntervalSkipList.



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# File 'lib/treetop/runtime/interval_skip_list/interval_skip_list.rb', line 4

def initialize
  @head = HeadNode.new(max_height)
  @ranges = {}
  @probability = 0.5
end

Instance Attribute Details

#probability ⇒ Object (readonly)

Returns the value of attribute probability.



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# File 'lib/treetop/runtime/interval_skip_list/interval_skip_list.rb', line 2

def probability
  @probability
end

Instance Method Details

#containing(n) ⇒ Object 



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# File 'lib/treetop/runtime/interval_skip_list/interval_skip_list.rb', line 36

def containing(n)
  containing_with_node(n).first
end

#delete(marker) ⇒ Object 



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# File 'lib/treetop/runtime/interval_skip_list/interval_skip_list.rb', line 64

def delete(marker)
  range = ranges[marker]
  path_to_first_node = make_path
  first_node = find(range.first, path_to_first_node)

  cur_node = first_node
  cur_level = first_node.top_level
  while next_node_at_level_inside_range?(cur_node, cur_level, range)
    while can_ascend_from?(cur_node, cur_level) && next_node_at_level_inside_range?(cur_node, cur_level + 1, range)
      cur_level += 1
    end
    cur_node = unmark_forward_path_at_level(cur_node, cur_level, marker)
  end

  while node_inside_range?(cur_node, range)
    while can_descend_from?(cur_level) && next_node_at_level_outside_range?(cur_node, cur_level, range)
      cur_level -= 1
    end
    cur_node = unmark_forward_path_at_level(cur_node, cur_level, marker)
  end
  last_node = cur_node

  first_node.endpoint_of.delete(marker)
  if first_node.endpoint_of.empty?
    first_node.delete(path_to_first_node)
  end

  last_node.endpoint_of.delete(marker)
  if last_node.endpoint_of.empty?
    path_to_last_node = make_path
    find(range.last, path_to_last_node)
    last_node.delete(path_to_last_node)
  end
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/treetop/runtime/interval_skip_list/interval_skip_list.rb', line 14

def empty?
  head.forward[0].nil?
end

#expire(range, length_change) ⇒ Object 



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# File 'lib/treetop/runtime/interval_skip_list/interval_skip_list.rb', line 18

def expire(range, length_change)
  expired_markers, first_node_after_range = overlapping(range)
  expired_markers.each { |marker| delete(marker) }
  first_node_after_range.propagate_length_change(length_change)    
end

#insert(range, marker) ⇒ Object 



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# File 'lib/treetop/runtime/interval_skip_list/interval_skip_list.rb', line 40

def insert(range, marker)
  ranges[marker] = range
  first_node = insert_node(range.first)
  first_node.endpoint_of.push(marker)
  last_node = insert_node(range.last)
  last_node.endpoint_of.push(marker)

  cur_node = first_node
  cur_level = first_node.top_level
  while next_node_at_level_inside_range?(cur_node, cur_level, range)
    while can_ascend_from?(cur_node, cur_level) && next_node_at_level_inside_range?(cur_node, cur_level + 1, range)
      cur_level += 1
    end
    cur_node = mark_forward_path_at_level(cur_node, cur_level, marker)
  end

  while node_inside_range?(cur_node, range)
    while can_descend_from?(cur_level) && next_node_at_level_outside_range?(cur_node, cur_level, range)
      cur_level -= 1 
    end
    cur_node = mark_forward_path_at_level(cur_node, cur_level, marker)
  end
end

#max_height ⇒ Object 



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# File 'lib/treetop/runtime/interval_skip_list/interval_skip_list.rb', line 10

def max_height
  3
end

#overlapping(range) ⇒ Object 



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# File 'lib/treetop/runtime/interval_skip_list/interval_skip_list.rb', line 24

def overlapping(range)
  markers, first_node = containing_with_node(range.first)

  cur_node = first_node
  begin
    markers.concat(cur_node.forward_markers.flatten)
    cur_node = cur_node.forward[0]
  end while cur_node.key < range.last

  return markers.uniq, cur_node
end