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.
  @data_old[@start_old .. @end_old].each { |e| s << encode("< ") + e + encode("\n") } unless block.remove.empty?
  s << encode("---\n") if block.op == "!"
  @data_new[@start_new .. @end_new].each { |e| s << encode("> ") + e + encode("\n") } unless block.insert.empty?
  s
end