Module: ULID::Generate

Includes:
Constants
Included in:
Identifier
Defined in:
lib/ulid/generate.rb

Constant Summary

Constants included from Constants

Constants::B32REF, Constants::ENCODING, Constants::MAX_ENTROPY, Constants::MAX_TIME, Constants::MIN_ENTROPY, Constants::MIN_TIME

Instance Method Summary collapse

Instance Method Details

#encode32 ⇒ Object

returns the binary ULID as Base32 encoded string.



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# File 'lib/ulid/generate.rb', line 10

def encode32
  # Optimized unrolled loop ahead.
  # From https://github.com/RobThree/NUlid
  # via https://github.com/oklog/ulid/blob/c3c01856f7e43fa64133819126887124d5f05e39/ulid.go#L154

  id = @bytes.bytes

  output = ''

  # Base32 encodes 5 bits of each byte of the input in each byte of the
  # output. That means each input byte produces >1 output byte and some
  # output bytes encode parts of multiple input bytes.
  #
  # The end result is a human / URL friendly output string that can be
  # decoded into the original bytes.

  # 10 byte timestamp
  output << ENCODING[(id[0]&224)>>5]
  output << ENCODING[id[0]&31]
  output << ENCODING[(id[1]&248)>>3]
  output << ENCODING[((id[1]&7)<<2)|((id[2]&192)>>6)]
  output << ENCODING[(id[2]&62)>>1]
  output << ENCODING[((id[2]&1)<<4)|((id[3]&240)>>4)]
  output << ENCODING[((id[3]&15)<<1)|((id[4]&128)>>7)]
  output << ENCODING[(id[4]&124)>>2]
  output << ENCODING[((id[4]&3)<<3)|((id[5]&224)>>5)]
  output << ENCODING[id[5]&31]

  # 16 bytes of entropy
  output << ENCODING[(id[6]&248)>>3]
  output << ENCODING[((id[6]&7)<<2)|((id[7]&192)>>6)]
  output << ENCODING[(id[7]&62)>>1]
  output << ENCODING[((id[7]&1)<<4)|((id[8]&240)>>4)]
  output << ENCODING[((id[8]&15)<<1)|((id[9]&128)>>7)]
  output << ENCODING[(id[9]&124)>>2]
  output << ENCODING[((id[9]&3)<<3)|((id[10]&224)>>5)]
  output << ENCODING[id[10]&31]
  output << ENCODING[(id[11]&248)>>3]
  output << ENCODING[((id[11]&7)<<2)|((id[12]&192)>>6)]
  output << ENCODING[(id[12]&62)>>1]
  output << ENCODING[((id[12]&1)<<4)|((id[13]&240)>>4)]
  output << ENCODING[((id[13]&15)<<1)|((id[14]&128)>>7)]
  output << ENCODING[(id[14]&124)>>2]
  output << ENCODING[((id[14]&3)<<3)|((id[15]&224)>>5)]
  output << ENCODING[id[15]&31]

  output
end

#millisecond_time ⇒ Object 



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# File 'lib/ulid/generate.rb', line 63

def millisecond_time
  (@time.to_r * 1_000).to_i
end

#random_bytes ⇒ Object 



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# File 'lib/ulid/generate.rb', line 59

def random_bytes
  SecureRandom.random_bytes(10)
end

#time_bytes ⇒ Object

THIS IS CORRECT (to the ULID spec)



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# File 'lib/ulid/generate.rb', line 68

def time_bytes
  id = []

  t = millisecond_time

  # via https://github.com/oklog/ulid/blob/c3c01856f7e43fa64133819126887124d5f05e39/ulid.go#L295
  id << [t >> 40].pack('c')
  id << [t >> 32].pack('c')
  id << [t >> 24].pack('c')
  id << [t >> 16].pack('c')
  id << [t >> 8].pack('c')
  id << [t].pack('c')

  id.join
end