class OpenSSL::Config

def extract_reference(value)
  rest = ''
  if m = value.match(/\(([^)]*)\)|\{([^}]*)\}/)
    value = m[1] || m[2]
    rest = m.post_match
  elsif [?(, ?{].include?(value[0])
    raise ConfigError, "no close brace"
  end
  if m = value.match(/[a-zA-Z0-9_]*(?:::[a-zA-Z0-9_]*)?/)
    return m[0], m.post_match + rest
  else
    raise
  end
end