Coverage for /pythoncovmergedfiles/medio/medio/src/python-crc32c/src/google_crc32c/cext.py: 83%

1# Copyright 2020 Google LLC 

2# 

3# Licensed under the Apache License, Version 2.0 (the "License"); 

4# you may not use this file except in compliance with the License. 

5# You may obtain a copy of the License at 

6# 

7# https://www.apache.org/licenses/LICENSE-2.0 

8# 

9# Unless required by applicable law or agreed to in writing, software 

10# distributed under the License is distributed on an "AS IS" BASIS, 

11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 

12# See the License for the specific language governing permissions and 

13# limitations under the License. 

14 

15import struct 

16 

17# NOTE: ``__config__`` **must** be the first import because it (may) 

18# modify the search path used to locate shared libraries. 

19import google_crc32c.__config__ # type: ignore 

20from google_crc32c._crc32c import extend # type: ignore 

21from google_crc32c._crc32c import value # type: ignore 

22from google_crc32c._checksum import CommonChecksum 

23 

24 

25class Checksum(CommonChecksum): 

26 """Hashlib-alike helper for CRC32C operations. 

27 

28 Args: 

29 initial_value (Optional[bytes]): the initial chunk of data from 

30 which the CRC32C checksum is computed. Defaults to b''. 

31 """ 

32 

33 __slots__ = ("_crc",) 

34 

35 def __init__(self, initial_value=b""): 

36 self._crc = value(initial_value) 

37 

38 def update(self, chunk): 

39 """Update the checksum with a new chunk of data. 

40 

41 Args: 

42 chunk (Optional[bytes]): a chunk of data used to extend 

43 the CRC32C checksum. 

44 """ 

45 self._crc = extend(self._crc, chunk)