module Register

  # A label is a placeholder for it's next Instruction
  # It's function is not to turn into code, but to be a valid brnch target
  #
  # So branches and Labels are pairs, fan out, fan in
  #
  #

  class Label < Instruction
    def initialize source , name , nekst = nil
      super(source , nekst)
      @name = name
    end
    attr_reader :name

    def to_s
      "Label: #{@name} (#{self.next.class})"
    end

    def to_ac labels = []
      return [] if labels.include?(self)
      labels << self
      super
    end

    def length labels = []
      return 0 if labels.include?(self)
      labels << self
      ret = 1
      ret += self.next.length(labels) if self.next
      ret
    end

    def assemble io
    end

    def assemble_all io , labels = []
      return if labels.include?(self)
      labels << self
      self.next.assemble_all(io,labels)
    end

    def total_byte_length labels = []
      return 0 if labels.include?(self)
      labels << self
      ret = self.next.total_byte_length(labels)
      #puts "#{self.class.name} return #{ret}"
      ret
    end

    # labels have the same position as their next
    def set_position position , labels = []
      return position if labels.include?(self)
      labels << self
      self.position = position
      self.next.set_position(position,labels)
    end

    def each_label labels =[] , &block
      return if labels.include?(self)
      labels << self
      block.yield(self)
      super
    end
  end
end