class Diff::LCS::Hunk

def old_diff
  warn 'Expecting only one block in an old diff hunk!' if @blocks.size > 1
  op_act = { '+' => 'a', '-' => 'd', '!' => 'c' }
  block = @blocks[0]
  # Calculate item number range. Old diff range is just like a context
  # diff range, except the ranges are on one line with the action between
  # them.
  s = encode("#{context_range(:old)}#{op_act[block.op]}#{context_range(:new)}\n")
  # If removing anything, just print out all the remove lines in the hunk
  # which is just all the remove lines in the block.
  unless block.remove.empty?
    @data_old[@start_old..@end_old].each { |e| s << encode('< ') + e + encode("\n") }
  end
  s << encode("---\n") if block.op == '!'
  unless block.insert.empty?
    @data_new[@start_new..@end_new].each { |e| s << encode('> ') + e + encode("\n") }
  end
  s
end