Method: Tamper::ExistencePack#encode

Defined in:
lib/tamper/existence_pack.rb

#encode(guid) ⇒ Object 



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# File 'lib/tamper/existence_pack.rb', line 18

def encode(guid)
  guid_diff  = guid.to_i - @last_guid
  guid_diff += 1 if @current_chunk.empty? && @output.empty? && guid.to_i > 0

  if guid_diff == 1 || guid.to_i == 0  # guid is 1 step forward
    @current_chunk << '1'
    @run_counter += 1

  elsif guid_diff <= 0  # somehow we went backwards or didn't change guid on iteration
    raise ArgumentError, "Error: data was not sorted by GUID (got #{@last_guid}, then #{guid})!"

  elsif guid_diff > 40  # big gap, encode with skip control char
    dump_keep(@current_chunk, @run_counter)

    @output += control_code(:skip, guid_diff - 1)
    @current_chunk = '1'
    @run_counter   = 1

  else # skips < 40 should just be encoded as '0'
    if @run_counter > 40    # first check if a run came before this 0; if so dump it
      dump_keep(@current_chunk, @run_counter)
      @current_chunk = ''
      @run_counter = 0
    end

    @current_chunk += ('0' * (guid_diff - 1))
    @current_chunk << '1'
    @run_counter = 1
  end

  @last_guid = guid.to_i
end