Class: Rope::InteriorNode

Inherits:
BasicNode show all
Defined in:
lib/rope/interior_node.rb

Overview

Specifies an interior node. Its underlying data is retrieved by combining its children recursively.

Instance Attribute Summary collapse

Attributes inherited from BasicNode

#depth, #length

Instance Method Summary collapse

Methods inherited from BasicNode

#+, #segment, #to_primitive

Constructor Details

#initialize(left, right) ⇒ InteriorNode

Initializes a new concatenation node.



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# File 'lib/rope/interior_node.rb', line 11

def initialize(left, right)
  @left = left
  @right = right

  @length = left.length + right.length
  @depth = [left.depth, right.depth].max + 1
end

Instance Attribute Details

#left ⇒ Object (readonly)

Left and right nodes



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# File 'lib/rope/interior_node.rb', line 8

def left
  @left
end

#right ⇒ Object (readonly)

Left and right nodes



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# File 'lib/rope/interior_node.rb', line 8

def right
  @right
end

Instance Method Details

#data ⇒ Object

Gets the underlying data in the tree



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# File 'lib/rope/interior_node.rb', line 20

def data
  left.data + right.data
end

#freeze ⇒ Object

Freeze is redefined to freeze the subtree; used when dup’ing a Rope to protect against aliasing



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# File 'lib/rope/interior_node.rb', line 73

def freeze
  unless frozen?
    super
    @left.freeze  unless @left.frozen?
    @right.freeze unless @right.frozen?
  end
  self
end

#rebalance! ⇒ Object

Rebalances this tree



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# File 'lib/rope/interior_node.rb', line 83

def rebalance!
  # TODO
end

#replace!(index, length, substr) ⇒ Object

Overwrites data at index with substr

Returns self, however leaf nodes may return a new interior node if the replace! causes a leaf to be split



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# File 'lib/rope/interior_node.rb', line 120

def replace!(index, length, substr)
  # We may be frozen, so this all gets reified into a new node or overwrites on ourselves 
  new_left  = @left
  new_right = @right

  # Translate to positive index if given a negative one
  if index < 0
    index += @length
  end

  rindex = index - @left.length
  if(index == 0 && length == @left.length)
  	#substr exactly replaces left sub-tree
  	new_left = LeafNode.new(substr)
  elsif(index == @left.length && length == @right.length)
  	#substr exactly replaces right sub-tree
  	new_right = LeafNode.new(substr)
  elsif rindex < 0
  	if(index + length <= @left.length)
  		#Replacement segment is a subsection of the left tree
     
     #Requested index is in the left subtree, and a split may occur
     new_left = @left.replace!(index, length, substr)
  	else
   	#Replacement segement is a subsection of left tree along with a subsection of the right tree
   	left_count = @left.length - index

   	new_left = InteriorNode.new(
   		@left.subtree(0, index),
   		LeafNode.new(substr)
   	)
   	new_right = @right.subtree(rindex + length, @right.length - (rindex + length))
   end
  else
    # Requested index is in the right subtree, and a split may occur
    new_right = @right.replace!(rindex, length, substr)
  end

  if(frozen?)
    InteriorNode.new(new_left, new_right)
  else
    #Length could have changed if the substr replaced a section of a different size or there was an append
    @left   = new_left
    @right  = new_right
    @length = @left.length + @right.length
    @depth  = [left.depth, right.depth].max + 1
    self
  end
end

#slice(arg0, *args) ⇒ Object

Gets a slice of the underlying data in the tree



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# File 'lib/rope/interior_node.rb', line 25

def slice(arg0, *args)
  if args.length == 0
    if arg0.is_a?(Fixnum)
      slice(arg0, 1)
    elsif arg0.is_a?(Range)
      from, to = arg0.minmax

      # Special case when the range doesn't actually describe a valid range
      return nil if from.nil? || to.nil?

      # Normalize so both from and to are positive indices
      if from < 0
        from += @length
      end
      if to < 0
        to += @length
      end

      if from <= to
        subtree(from, (to - from) + 1)
      else
        # Range first is greater than range last
        # Return empty string to match what String does
        raise "TODO"
      end
    end

    # TODO: arg0.is_a?(Range)
    # TODO: arg0.is_a?(Regexp)
    # TODO: arg0.is_a?(String)
  else
    arg1 = args[0] # may be slightly confusing; refer to method definition
    if arg0.is_a?(Fixnum) && arg1.is_a?(Fixnum) # Fixnum, Fixnum
      if arg1 >= 0
        subtree(arg0, arg1)
      else
        # Negative length, return nil to match what String does
        nil
      end
    end

    # TODO: arg0.is_a?(Regexp) && arg1.is_a?(Fixnum)
  end
end

#subtree(from, length) ⇒ Object

Returns a node that represents a slice of this tree



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# File 'lib/rope/interior_node.rb', line 88

def subtree(from, length)
  # Translate to positive index if given a negative one
  if from < 0
    from += @length
  end

  # If more than @length characters are requested, truncate
  length = [(@length - from), length].min

  # Entire length requested
  return self if length == @length

  # Check if the requested subtree is entirely in the right subtree
  rfrom = from - @left.length
  return @right.subtree(rfrom, length) if rfrom >= 0

  llen = @left.length - from
  rlen = length - llen
  if rlen > 0
    # Requested subtree overlaps both the left and the right subtree
    @left.subtree(from, llen) + @right.subtree(0, rlen)
  else
    # Requested subtree is entirely in the left subtree
    @left.subtree(from, length)
  end
end