class Google::Protobuf::RepeatedField

def define_array_wrapper_method(method_name)
  define_method(method_name) do |*args, &block|
    arr = self.to_a
    result = arr.send(method_name, *args)
    self.replace(arr)
    return result if result
    return block ? block.call : result
  end
end

def define_array_wrapper_with_result_method(method_name)
  define_method(method_name) do |*args, &block|
    # result can be an Enumerator, Array, or nil
    # Enumerator can sometimes be returned if a block is an optional argument and it is not passed in
    # nil usually specifies that no change was made
    result = self.to_a.send(method_name, *args, &block)
    if result
      new_arr = result.to_a
      self.replace(new_arr)
      if result.is_a?(Enumerator)
        # generate a fresh enum; rewinding the exiting one, in Ruby 2.2, will
        # reset the enum with the same length, but all the #next calls will
        # return nil
        result = new_arr.to_enum
        # generate a wrapper enum so any changes which occur by a chained
        # enum can be captured
        ie = ProxyingEnumerator.new(self, result)
        result = ie.to_enum
      end
    end
    result
  end
end

def empty?
  self.size == 0
end

def first(n=nil)
  n ? self[0..n] : self[0]
end

def last(n=nil)
  n ? self[(self.size-n-1)..-1] : self[-1]
end

def pop(n=nil)
  if n
    results = []
    n.times{ results << pop_one }
    return results
  else
    return pop_one
  end
end