| # Licensed to the Apache Software Foundation (ASF) under one or more |
| # contributor license agreements. See the NOTICE file distributed with |
| # this work for additional information regarding copyright ownership. |
| # The ASF licenses this file to You under the Apache License, Version 2.0 |
| # (the "License"); you may not use this file except in compliance with |
| # the License. You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| |
| """ |
| UUID generation utilities. |
| """ |
| |
| from __future__ import absolute_import # so we can import standard 'uuid' |
| |
| from random import randrange |
| from uuid import uuid4 |
| |
| from shortuuid import ShortUUID |
| |
| |
| # Alphanumeric without visually ambiguous characters; default length is 22 |
| UUID_BASE57 = ShortUUID() |
| |
| # Lower-case alphanumeric; default length is 25 |
| UUID_LOWERCASE_ALPHANUMERIC = ShortUUID(alphabet='abcdefghijklmnopqrstuvwxyz0123456789') |
| |
| |
| def generate_uuid(length=None, variant='base57'): |
| """ |
| A random string with varying degrees of guarantee of universal uniqueness. |
| |
| :param variant: |
| * ``base57`` (the default) uses a mix of upper and lowercase alphanumerics ensuring no visually |
| ambiguous characters; default length 22 |
| * ``alphanumeric`` uses lowercase alphanumeric; default length 25 |
| * ``uuid`` uses lowercase hexadecimal in the classic UUID format, including dashes; length is |
| always 36 |
| * ``hex`` uses lowercase hexadecimal characters but has no guarantee of uniqueness; default |
| length of 5 |
| """ |
| |
| if variant == 'base57': |
| the_id = UUID_BASE57.uuid() |
| if length is not None: |
| the_id = the_id[:length] |
| |
| elif variant == 'alphanumeric': |
| the_id = UUID_LOWERCASE_ALPHANUMERIC.uuid() |
| if length is not None: |
| the_id = the_id[:length] |
| |
| elif variant == 'uuid': |
| the_id = str(uuid4()) |
| |
| elif variant == 'hex': |
| length = length or 5 |
| # See: http://stackoverflow.com/a/2782859 |
| the_id = ('%0' + str(length) + 'x') % randrange(16 ** length) |
| |
| else: |
| raise ValueError('unsupported UUID variant: {0}'.format(variant)) |
| |
| return the_id |