mirror of
https://github.com/PiBrewing/craftbeerpi4.git
synced 2024-11-23 07:28:13 +01:00
137 lines
4.2 KiB
Python
137 lines
4.2 KiB
Python
""" Concise UUID generation. """
|
|
import binascii
|
|
import math
|
|
import os
|
|
import uuid as _uu
|
|
|
|
|
|
def int_to_string(number, alphabet, padding=None):
|
|
"""
|
|
Convert a number to a string, using the given alphabet.
|
|
The output has the most significant digit first.
|
|
"""
|
|
output = ""
|
|
alpha_len = len(alphabet)
|
|
while number:
|
|
number, digit = divmod(number, alpha_len)
|
|
output += alphabet[digit]
|
|
if padding:
|
|
remainder = max(padding - len(output), 0)
|
|
output = output + alphabet[0] * remainder
|
|
return output[::-1]
|
|
|
|
|
|
def string_to_int(string, alphabet):
|
|
"""
|
|
Convert a string to a number, using the given alphabet.
|
|
The input is assumed to have the most significant digit first.
|
|
"""
|
|
number = 0
|
|
alpha_len = len(alphabet)
|
|
for char in string:
|
|
number = number * alpha_len + alphabet.index(char)
|
|
return number
|
|
|
|
|
|
class ShortUUID(object):
|
|
def __init__(self, alphabet=None):
|
|
if alphabet is None:
|
|
alphabet = list("23456789ABCDEFGHJKLMNPQRSTUVWXYZ" "abcdefghijkmnopqrstuvwxyz")
|
|
|
|
self.set_alphabet(alphabet)
|
|
|
|
@property
|
|
def _length(self):
|
|
"""
|
|
Return the necessary length to fit the entire UUID given
|
|
the current alphabet.
|
|
"""
|
|
return int(math.ceil(math.log(2 ** 128, self._alpha_len)))
|
|
|
|
def encode(self, uuid, pad_length=None):
|
|
"""
|
|
Encode a UUID into a string (LSB first) according to the alphabet
|
|
|
|
If leftmost (MSB) bits are 0, the string might be shorter.
|
|
"""
|
|
if pad_length is None:
|
|
pad_length = self._length
|
|
return int_to_string(uuid.int, self._alphabet, padding=pad_length)
|
|
|
|
def decode(self, string, legacy=False):
|
|
"""
|
|
Decode a string according to the current alphabet into a UUID
|
|
Raises ValueError when encountering illegal characters
|
|
or a too-long string.
|
|
|
|
If string too short, fills leftmost (MSB) bits with 0.
|
|
|
|
Pass `legacy=True` if your UUID was encoded with a ShortUUID version
|
|
prior to 1.0.0.
|
|
"""
|
|
if legacy:
|
|
string = string[::-1]
|
|
return _uu.UUID(int=string_to_int(string, self._alphabet))
|
|
|
|
def uuid(self, name=None, pad_length=None):
|
|
"""
|
|
Generate and return a UUID.
|
|
|
|
If the name parameter is provided, set the namespace to the provided
|
|
name and generate a UUID.
|
|
"""
|
|
if pad_length is None:
|
|
pad_length = self._length
|
|
|
|
# If no name is given, generate a random UUID.
|
|
if name is None:
|
|
u = _uu.uuid4()
|
|
elif name.lower().startswith(("http://", "https://")):
|
|
u = _uu.uuid5(_uu.NAMESPACE_URL, name)
|
|
else:
|
|
u = _uu.uuid5(_uu.NAMESPACE_DNS, name)
|
|
return self.encode(u, pad_length)
|
|
|
|
def random(self, length=None):
|
|
"""
|
|
Generate and return a cryptographically-secure short random string
|
|
of the specified length.
|
|
"""
|
|
if length is None:
|
|
length = self._length
|
|
|
|
random_num = int(binascii.b2a_hex(os.urandom(length)), 16)
|
|
return int_to_string(random_num, self._alphabet, padding=length)[:length]
|
|
|
|
def get_alphabet(self):
|
|
"""Return the current alphabet used for new UUIDs."""
|
|
return "".join(self._alphabet)
|
|
|
|
def set_alphabet(self, alphabet):
|
|
"""Set the alphabet to be used for new UUIDs."""
|
|
|
|
# Turn the alphabet into a set and sort it to prevent duplicates
|
|
# and ensure reproducibility.
|
|
new_alphabet = list(sorted(set(alphabet)))
|
|
if len(new_alphabet) > 1:
|
|
self._alphabet = new_alphabet
|
|
self._alpha_len = len(self._alphabet)
|
|
else:
|
|
raise ValueError("Alphabet with more than " "one unique symbols required.")
|
|
|
|
def encoded_length(self, num_bytes=16):
|
|
"""
|
|
Returns the string length of the shortened UUID.
|
|
"""
|
|
factor = math.log(256) / math.log(self._alpha_len)
|
|
return int(math.ceil(factor * num_bytes))
|
|
|
|
|
|
# For backwards compatibility
|
|
_global_instance = ShortUUID()
|
|
encode = _global_instance.encode
|
|
decode = _global_instance.decode
|
|
uuid = _global_instance.uuid
|
|
random = _global_instance.random
|
|
get_alphabet = _global_instance.get_alphabet
|
|
set_alphabet = _global_instance.set_alphabet
|