From d9d009b981a75f888b4bcac32a4e0c8637ef1294 Mon Sep 17 00:00:00 2001
From: Andreas Kloeckner <inform@tiker.net>
Date: Wed, 10 Mar 2021 16:17:28 -0600
Subject: [PATCH] unordered_hash: update a hash instance, instead of forcing
creation of a new one
---
pytools/__init__.py | 17 +++++++++++++----
pytools/persistent_dict.py | 8 +++-----
test/test_pytools.py | 16 ++++++++--------
3 files changed, 24 insertions(+), 17 deletions(-)
diff --git a/pytools/__init__.py b/pytools/__init__.py
index c8cfa90..f1f1ebf 100644
--- a/pytools/__init__.py
+++ b/pytools/__init__.py
@@ -2623,7 +2623,7 @@ def resolve_name(name):
# {{{ unordered_hash
-def unordered_hash(hash_constructor, iterable):
+def unordered_hash(hash_instance, iterable, hash_constructor=None):
"""Using a hash algorithm given by the parameter-less constructor
*hash_constructor*, return a hash object whose internal state
depends on the entries of *iterable*, but not their order. If *hash*
@@ -2631,6 +2631,10 @@ def unordered_hash(hash_constructor, iterable):
the each entry *i* of the iterable must permit ``hash.upate(i)`` to
succeed. An example of *hash_constructor* is ``hashlib.sha256``
from :mod:`hashlib`. ``hash.digest_size`` must also be defined.
+ If *hash_constructor* is not provided, ``hash_instance.name`` is
+ used to deduce it.
+
+ :returns: the updated *hash_instance*.
.. warning::
@@ -2639,6 +2643,12 @@ def unordered_hash(hash_constructor, iterable):
.. versionadded:: 2021.2
"""
+
+ if hash_constructor is None:
+ from functools import partial
+ import hashlib
+ hash_constructor = partial(hashlib.new, hash_instance.name)
+
h_int = 0
for i in iterable:
h_i = hash_constructor()
@@ -2650,9 +2660,8 @@ def unordered_hash(hash_constructor, iterable):
# mix adjacent bits).
h_int = h_int ^ int.from_bytes(h_i.digest(), sys.byteorder)
- h = hash_constructor()
- h.update(h_int.to_bytes(h.digest_size, sys.byteorder))
- return h
+ hash_instance.update(h_int.to_bytes(hash_instance.digest_size, sys.byteorder))
+ return hash_instance
# }}}
diff --git a/pytools/persistent_dict.py b/pytools/persistent_dict.py
index f48027f..c3a7b1d 100644
--- a/pytools/persistent_dict.py
+++ b/pytools/persistent_dict.py
@@ -294,11 +294,9 @@ class KeyBuilder:
def update_for_frozenset(self, key_hash, key):
from pytools import unordered_hash
- self.rec(key_hash,
- unordered_hash(
- self.new_hash,
- (self.rec(self.new_hash(), key_i).digest() for key_i in key)
- ).digest())
+ unordered_hash(
+ key_hash,
+ (self.rec(self.new_hash(), key_i).digest() for key_i in key))
@staticmethod
def update_for_NoneType(key_hash, key): # noqa
diff --git a/test/test_pytools.py b/test/test_pytools.py
index 49a4390..356e47c 100644
--- a/test/test_pytools.py
+++ b/test/test_pytools.py
@@ -446,15 +446,15 @@ def test_unordered_hash():
random.shuffle(lst)
from pytools import unordered_hash
- assert (unordered_hash(hashlib.sha256, lorig).digest()
- == unordered_hash(hashlib.sha256, lst).digest())
- assert (unordered_hash(hashlib.sha256, lorig).digest()
- == unordered_hash(hashlib.sha256, lorig).digest())
- assert (unordered_hash(hashlib.sha256, lorig).digest()
- != unordered_hash(hashlib.sha256, lorig[:-1]).digest())
+ assert (unordered_hash(hashlib.sha256(), lorig).digest()
+ == unordered_hash(hashlib.sha256(), lst).digest())
+ assert (unordered_hash(hashlib.sha256(), lorig).digest()
+ == unordered_hash(hashlib.sha256(), lorig).digest())
+ assert (unordered_hash(hashlib.sha256(), lorig).digest()
+ != unordered_hash(hashlib.sha256(), lorig[:-1]).digest())
lst[0] = b"aksdjfla;sdfjafd"
- assert (unordered_hash(hashlib.sha256, lorig).digest()
- != unordered_hash(hashlib.sha256, lst).digest())
+ assert (unordered_hash(hashlib.sha256(), lorig).digest()
+ != unordered_hash(hashlib.sha256(), lst).digest())
if __name__ == "__main__":
--
GitLab