class RubyLex

def self.interpolate_ripper_ignored_tokens(code, tokens)

With interpolated tokens, tokens.map(&:tok).join will be equal to code.
Example: DATA part, token after heredoc_beg when heredoc has unclosed embexpr.
Some part of the code is not included in Ripper's token. 
def self.interpolate_ripper_ignored_tokens(code, tokens)
  line_positions = [0]
  code.lines.each do |line|
    line_positions << line_positions.last + line.bytesize
  end
  prev_byte_pos = 0
  interpolated = []
  prev_line = 1
  tokens.each do |t|
    line, col = t.pos
    byte_pos = line_positions[line - 1] + col
    if prev_byte_pos < byte_pos
      tok = code.byteslice(prev_byte_pos...byte_pos)
      pos = [prev_line, prev_byte_pos - line_positions[prev_line - 1]]
      interpolated << Ripper::Lexer::Elem.new(pos, :on_ignored_by_ripper, tok, 0)
      prev_line += tok.count("\n")
    end
    interpolated << t
    prev_byte_pos = byte_pos + t.tok.bytesize
    prev_line += t.tok.count("\n")
  end
  if prev_byte_pos < code.bytesize
    tok = code.byteslice(prev_byte_pos..)
    pos = [prev_line, prev_byte_pos - line_positions[prev_line - 1]]
    interpolated << Ripper::Lexer::Elem.new(pos, :on_ignored_by_ripper, tok, 0)
  end
  interpolated
end