Added delete option to database storage.

venv/Lib/site-packages/google_crc32c/cffi.py

@@ -0,0 +1,72 @@
+# Copyright 2020 Google LLC
+#
+# Licensed 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
+#
+#     https://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.
+
+import struct
+
+# NOTE: ``__config__`` **must** be the first import because it (may)
+#       modify the search path used to locate shared libraries.
+import google_crc32c.__config__
+import google_crc32c._crc32c_cffi
+from google_crc32c._checksum import CommonChecksum
+
+
+def extend(crc, chunk):
+    """Update an existing CRC checksum with new chunk of data.
+
+    Args
+        crc (int): An existing CRC check sum.
+        chunk (Union[bytes, List[int], Tuple[int]]): A new chunk of data.
+            Intended to be a byte string or similar.
+
+    Returns
+        int: New CRC checksum computed by extending existing CRC
+        with ``chunk``.
+    """
+    return google_crc32c._crc32c_cffi.lib.crc32c_extend(crc, chunk, len(chunk))
+
+
+def value(chunk):
+    """Compute a CRC checksum for a chunk of data.
+
+    Args
+        chunk (Union[bytes, List[int], Tuple[int]]): A new chunk of data.
+            Intended to be a byte string or similar.
+
+    Returns
+        int: New CRC checksum computed for ``chunk``.
+    """
+    return google_crc32c._crc32c_cffi.lib.crc32c_value(chunk, len(chunk))
+
+
+class Checksum(CommonChecksum):
+    """Hashlib-alike helper for CRC32C operations.
+
+    Args:
+        initial_value (Optional[bytes]): the initial chunk of data from
+            which the CRC32C checksum is computed.  Defaults to b''.
+    """
+
+    __slots__ = ("_crc",)
+
+    def __init__(self, initial_value=b""):
+        self._crc = value(initial_value)
+
+    def update(self, chunk):
+        """Update the checksum with a new chunk of data.
+
+        Args:
+            chunk (Optional[bytes]): a chunk of data used to extend
+                the CRC32C checksum.
+        """
+        self._crc = extend(self._crc, chunk)