""" ``encoding`` module.
"""
from base64 import b64encode
BASE64_ALTCHARS = "-_".encode("latin1")
[docs]def encode_keys(mapping, key_encode):
"""Encodes all keys in mapping with ``key_encode`` callable.
Returns tuple of: key mapping (encoded key => key) and
value mapping (encoded key => value).
>>> mapping = {'k1': 1, 'k2': 2}
>>> keys, mapping = encode_keys(mapping,
... lambda k: str(base64_encode(k).decode('latin1')))
>>> sorted(keys.items())
[('azE=', 'k1'), ('azI=', 'k2')]
>>> sorted(mapping.items())
[('azE=', 1), ('azI=', 2)]
"""
key_mapping = {}
encoded_mapping = {}
for key in mapping:
encoded_key = key_encode(key)
key_mapping[encoded_key] = key
encoded_mapping[encoded_key] = mapping[key]
return key_mapping, encoded_mapping
[docs]def string_encode(key):
"""Encodes ``key`` with UTF-8 encoding."""
if isinstance(key, str):
return key.encode("UTF-8")
else:
return key # pragma: nocover
[docs]def base64_encode(key):
"""Encodes ``key`` with base64 encoding.
>>> result = base64_encode('my key')
>>> result == 'bXkga2V5'.encode('latin1')
True
"""
if isinstance(key, str):
key = key.encode("UTF-8")
return b64encode(key, BASE64_ALTCHARS)
[docs]def hash_encode(hash_factory):
"""Encodes ``key`` with given hash function.
See list of available hashes in ``hashlib``
module from Python Statndard Library.
Additional algorithms may also be available
depending upon the OpenSSL library that Python
uses on your platform.
>>> try:
... from hashlib import sha1
... key_encode = hash_encode(sha1)
... r = base64_encode(key_encode('my key'))
... assert r == 'RigVwkWdSuGyFu7au08PzUMloU8='.encode('latin1')
... except ImportError: # Python2.4
... pass
"""
assert callable(hash_factory)
def key_encode(key):
h = hash_factory()
if isinstance(key, str):
key = key.encode("UTF-8")
h.update(key)
return h.digest()
return key_encode