CSV::Parser::InputsScanner#adjust_last_keep

# File tmp/rubies/ruby-3.3.0/lib/csv/parser.rb, line 257
def adjust_last_keep
  # trace(__method__, :start)

  keep = @keeps.last
  # trace(__method__, :done, :empty) if keep.nil?
  return if keep.nil?

  scanner, start, buffer = keep
  string = @scanner.string
  if @scanner != scanner
    start = 0
  end
  if start == 0 and @scanner.eos?
    keep_data = string
  else
    keep_data = string.byteslice(start, @scanner.pos - start)
  end
  if keep_data
    if buffer
      buffer << keep_data
    else
      keep[2] = keep_data.dup
    end
  end

  # trace(__method__, :done)
end