def fingerprint(blob):
"""Compute the fingerprint of its input.
This blob can contain an integer, a string, a dict or
an object with a fingerprint method.
"""
# is it an integer?
try:
mpz_value = mpz(blob)
except (TypeError, ValueError):
pass
else:
string = utils.mpztob64(mpz_value)
return b64encode(crypthash(string).digest())
# is it a string?
if isinstance(blob, str):
return b64encode(crypthash(blob).digest())
# is it a list?
if isinstance(blob, (list, tuple)):
list_of_fingerprints = [fingerprint(i) for i in blob]
string = json.dumps(list_of_fingerprints, separators=(',', ':'))
return b64encode(crypthash(string).digest())
# is it a dict?
if isinstance(blob, dict):
# is this dict already a hash of something?
if "#" in blob:
return blob["#"]
# otherwise, transform dict into array and fingerprint it
keys = sorted(blob)
list_of_fingerprints = [fingerprint([k, blob[k]]) \
for k in keys]
string = json.dumps(list_of_fingerprints, separators=(',', ':'))
return b64encode(crypthash(string).digest())
# is it None
if blob is None:
return fingerprint('None')
# is it an object?
try:
# is it a class for which we can compute a fingerprint?
return blob.fingerprint()
except AttributeError:
pass
assert False, "fingerprint cannot parse object"
def exportable(blob, f_dict=None):
"""Produces something that only contains strings, lists and dicts,
so that it can be given as input for json.dumps for instance.
In particular:
- convert all integers to base64
- make sure that all elements of all lists can be dumped
- make sure that all elements of all dictionaries can be dumped
- convert other objects into a dictionary that can be dumped
"""
if f_dict is None:
f_dict = {}
# is it an integer?
try:
mpz_value = mpz(blob)
except (TypeError, ValueError):
pass
else:
return utils.mpztob64(mpz_value), f_dict
# is it a class for which we can compute a fingerprint?
try:
result, f_dict = blob.exportable(f_dict)
return result, f_dict
except AttributeError:
pass
# is it a string?
if isinstance(blob, str):
return blob, f_dict
# is it a list?
elif isinstance(blob, (list, tuple)):
result = []
for b in blob:
e, f_dict = exportable(b, f_dict)
result.append(e)
return result, f_dict
# is it a dictionary?
elif isinstance(blob, dict):
dict_to_export = {}
for k in blob.keys():
dict_to_export[k], f_dict = exportable(blob[k], f_dict)
return dict_to_export, f_dict
print "I cannot parse this:", blob
assert False, "exportable cannot parse object"
