Circular Buffer

circular_buffer.rb

class CircularBuffer
  class BufferEmptyException < StandardError; end
  class BufferFullException < StandardError; end

  attr_reader :buffer, :buffer_size
  attr_accessor :read_id, :write_id

  def initialize(buffer_size)
    @buffer = []
    @buffer_size = buffer_size
    @read_id = 1
    @write_id = 1
    buffer_size.times { |n| buffer << Element.new(n + 1) }
  end

  def read
    read_validation
    value = element(read_id).value
    element(read_id).clear
    rotate_read_id
    value
  end

  def write(value)
    return if value.nil?
    write_validation
    element(write_id).value = value
    rotate_write_id
  end

  def write!(value)
    if value && full?
      element(write_id).clear
      rotate_read_id
    end
    write(value)
  end

  def clear
    buffer.each { |element| element.value = nil }
  end

  private

  def empty?
    buffer.all? { |element| element.value.nil? }
  end

  def full?
    buffer.none? { |element| element.value.nil? }
  end

  def element(id)
    buffer.find { |element| element.id == id }
  end

  def rotate_read_id
    read_id == buffer_size ? (self.read_id = 1) : (self.read_id += 1)
  end

  def rotate_write_id
    write_id == buffer_size ? (self.write_id = 1) : (self.write_id += 1)
  end

  def read_validation
    fail BufferEmptyException if empty?
  end

  def write_validation
    fail BufferFullException if full?
  end
end

class Element
  attr_reader :id
  attr_accessor :value

  def initialize(id)
    @id = id
    @value = nil
  end

  def clear
    self.value = nil
  end
end