Method: DomainName::Punycode.encode

Defined in:
lib/domain_name/punycode.rb

.encode(string) ⇒ Object

Encode a string in Punycode



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# File 'lib/domain_name/punycode.rb', line 101

def encode(string)
  input = string.unpack('U*')
  output = ''

  # Initialize the state
  n = INITIAL_N
  delta = 0
  bias = INITIAL_BIAS

  # Handle the basic code points
  input.each { |cp| output << cp.chr if cp < 0x80 }

  h = b = output.length

  # h is the number of code points that have been handled, b is the
  # number of basic code points, and out is the number of characters
  # that have been output.

  output << DELIMITER if b > 0

  # Main encoding loop

  while h < input.length
    # All non-basic code points < n have been handled already.  Find
    # the next larger one

    m = MAXINT
    input.each { |cp|
      m = cp if (n...m) === cp
    }

    # Increase delta enough to advance the decoder's <n,i> state to
    # <m,0>, but guard against overflow

    delta += (m - n) * (h + 1)
    raise BufferOverflowError if delta > MAXINT
    n = m

    input.each { |cp|
      # AMC-ACE-Z can use this simplified version instead
      if cp < n
        delta += 1
        raise BufferOverflowError if delta > MAXINT
      elsif cp == n
        # Represent delta as a generalized variable-length integer
        q = delta
        k = BASE
        loop {
          t = k <= bias ? TMIN : k - bias >= TMAX ? TMAX : k - bias
          break if q < t
          q, r = (q - t).divmod(BASE - t)
          output << ENCODE_DIGIT[t + r, false]
          k += BASE
        }

        output << ENCODE_DIGIT[q, false]

        # Adapt the bias
        delta = h == b ? delta / DAMP : delta >> 1
        delta += delta / (h + 1)
        bias = 0
        while delta > CUTOFF
          delta /= LOBASE
          bias += BASE
        end
        bias += (LOBASE + 1) * delta / (delta + SKEW)

        delta = 0
        h += 1
      end
    }

    delta += 1
    n += 1
  end

  output
end