CSV::Parser::InputsScanner#each_line

# File tmp/rubies/ruby-3.1.3/lib/csv/parser.rb, line 97
def each_line(row_separator)
  return enum_for(__method__, row_separator) unless block_given?
  buffer = nil
  input = @scanner.rest
  position = @scanner.pos
  offset = 0
  n_row_separator_chars = row_separator.size
  # trace(__method__, :start, line, input)
  while true
    input.each_line(row_separator) do |line|
      @scanner.pos += line.bytesize
      if buffer
        if n_row_separator_chars == 2 and
          buffer.end_with?(row_separator[0]) and
          line.start_with?(row_separator[1])
          buffer << line[0]
          line = line[1..-1]
          position += buffer.bytesize + offset
          @scanner.pos = position
          offset = 0
          yield(buffer)
          buffer = nil
          next if line.empty?
        else
          buffer << line
          line = buffer
          buffer = nil
        end
      end
      if line.end_with?(row_separator)
        position += line.bytesize + offset
        @scanner.pos = position
        offset = 0
        yield(line)
      else
        buffer = line
      end
    end
    break unless read_chunk
    input = @scanner.rest
    position = @scanner.pos
    offset = -buffer.bytesize if buffer
  end
  yield(buffer) if buffer
end