/usr/lib/python3/dist-packages/sqlalchemy/util/_collections.py is in python3-sqlalchemy 1.1.11+ds1-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 | # util/_collections.py
# Copyright (C) 2005-2017 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""Collection classes and helpers."""
from __future__ import absolute_import
import weakref
import operator
from .compat import threading, itertools_filterfalse, string_types, \
binary_types
from . import py2k
import types
import collections
EMPTY_SET = frozenset()
class AbstractKeyedTuple(tuple):
__slots__ = ()
def keys(self):
"""Return a list of string key names for this :class:`.KeyedTuple`.
.. seealso::
:attr:`.KeyedTuple._fields`
"""
return list(self._fields)
class KeyedTuple(AbstractKeyedTuple):
"""``tuple`` subclass that adds labeled names.
E.g.::
>>> k = KeyedTuple([1, 2, 3], labels=["one", "two", "three"])
>>> k.one
1
>>> k.two
2
Result rows returned by :class:`.Query` that contain multiple
ORM entities and/or column expressions make use of this
class to return rows.
The :class:`.KeyedTuple` exhibits similar behavior to the
``collections.namedtuple()`` construct provided in the Python
standard library, however is architected very differently.
Unlike ``collections.namedtuple()``, :class:`.KeyedTuple` is
does not rely on creation of custom subtypes in order to represent
a new series of keys, instead each :class:`.KeyedTuple` instance
receives its list of keys in place. The subtype approach
of ``collections.namedtuple()`` introduces significant complexity
and performance overhead, which is not necessary for the
:class:`.Query` object's use case.
.. versionchanged:: 0.8
Compatibility methods with ``collections.namedtuple()`` have been
added including :attr:`.KeyedTuple._fields` and
:meth:`.KeyedTuple._asdict`.
.. seealso::
:ref:`ormtutorial_querying`
"""
def __new__(cls, vals, labels=None):
t = tuple.__new__(cls, vals)
if labels:
t.__dict__.update(zip(labels, vals))
else:
labels = []
t.__dict__['_labels'] = labels
return t
@property
def _fields(self):
"""Return a tuple of string key names for this :class:`.KeyedTuple`.
This method provides compatibility with ``collections.namedtuple()``.
.. versionadded:: 0.8
.. seealso::
:meth:`.KeyedTuple.keys`
"""
return tuple([l for l in self._labels if l is not None])
def __setattr__(self, key, value):
raise AttributeError("Can't set attribute: %s" % key)
def _asdict(self):
"""Return the contents of this :class:`.KeyedTuple` as a dictionary.
This method provides compatibility with ``collections.namedtuple()``,
with the exception that the dictionary returned is **not** ordered.
.. versionadded:: 0.8
"""
return dict((key, self.__dict__[key]) for key in self.keys())
class _LW(AbstractKeyedTuple):
__slots__ = ()
def __new__(cls, vals):
return tuple.__new__(cls, vals)
def __reduce__(self):
# for pickling, degrade down to the regular
# KeyedTuple, thus avoiding anonymous class pickling
# difficulties
return KeyedTuple, (list(self), self._real_fields)
def _asdict(self):
"""Return the contents of this :class:`.KeyedTuple` as a dictionary."""
d = dict(zip(self._real_fields, self))
d.pop(None, None)
return d
class ImmutableContainer(object):
def _immutable(self, *arg, **kw):
raise TypeError("%s object is immutable" % self.__class__.__name__)
__delitem__ = __setitem__ = __setattr__ = _immutable
class immutabledict(ImmutableContainer, dict):
clear = pop = popitem = setdefault = \
update = ImmutableContainer._immutable
def __new__(cls, *args):
new = dict.__new__(cls)
dict.__init__(new, *args)
return new
def __init__(self, *args):
pass
def __reduce__(self):
return immutabledict, (dict(self), )
def union(self, d):
if not d:
return self
elif not self:
if isinstance(d, immutabledict):
return d
else:
return immutabledict(d)
else:
d2 = immutabledict(self)
dict.update(d2, d)
return d2
def __repr__(self):
return "immutabledict(%s)" % dict.__repr__(self)
class Properties(object):
"""Provide a __getattr__/__setattr__ interface over a dict."""
__slots__ = '_data',
def __init__(self, data):
object.__setattr__(self, '_data', data)
def __len__(self):
return len(self._data)
def __iter__(self):
return iter(list(self._data.values()))
def __add__(self, other):
return list(self) + list(other)
def __setitem__(self, key, object):
self._data[key] = object
def __getitem__(self, key):
return self._data[key]
def __delitem__(self, key):
del self._data[key]
def __setattr__(self, key, obj):
self._data[key] = obj
def __getstate__(self):
return {'_data': self._data}
def __setstate__(self, state):
object.__setattr__(self, '_data', state['_data'])
def __getattr__(self, key):
try:
return self._data[key]
except KeyError:
raise AttributeError(key)
def __contains__(self, key):
return key in self._data
def as_immutable(self):
"""Return an immutable proxy for this :class:`.Properties`."""
return ImmutableProperties(self._data)
def update(self, value):
self._data.update(value)
def get(self, key, default=None):
if key in self:
return self[key]
else:
return default
def keys(self):
return list(self._data)
def values(self):
return list(self._data.values())
def items(self):
return list(self._data.items())
def has_key(self, key):
return key in self._data
def clear(self):
self._data.clear()
class OrderedProperties(Properties):
"""Provide a __getattr__/__setattr__ interface with an OrderedDict
as backing store."""
__slots__ = ()
def __init__(self):
Properties.__init__(self, OrderedDict())
class ImmutableProperties(ImmutableContainer, Properties):
"""Provide immutable dict/object attribute to an underlying dictionary."""
__slots__ = ()
class OrderedDict(dict):
"""A dict that returns keys/values/items in the order they were added."""
__slots__ = '_list',
def __reduce__(self):
return OrderedDict, (self.items(),)
def __init__(self, ____sequence=None, **kwargs):
self._list = []
if ____sequence is None:
if kwargs:
self.update(**kwargs)
else:
self.update(____sequence, **kwargs)
def clear(self):
self._list = []
dict.clear(self)
def copy(self):
return self.__copy__()
def __copy__(self):
return OrderedDict(self)
def sort(self, *arg, **kw):
self._list.sort(*arg, **kw)
def update(self, ____sequence=None, **kwargs):
if ____sequence is not None:
if hasattr(____sequence, 'keys'):
for key in ____sequence.keys():
self.__setitem__(key, ____sequence[key])
else:
for key, value in ____sequence:
self[key] = value
if kwargs:
self.update(kwargs)
def setdefault(self, key, value):
if key not in self:
self.__setitem__(key, value)
return value
else:
return self.__getitem__(key)
def __iter__(self):
return iter(self._list)
def keys(self):
return list(self)
def values(self):
return [self[key] for key in self._list]
def items(self):
return [(key, self[key]) for key in self._list]
if py2k:
def itervalues(self):
return iter(self.values())
def iterkeys(self):
return iter(self)
def iteritems(self):
return iter(self.items())
def __setitem__(self, key, object):
if key not in self:
try:
self._list.append(key)
except AttributeError:
# work around Python pickle loads() with
# dict subclass (seems to ignore __setstate__?)
self._list = [key]
dict.__setitem__(self, key, object)
def __delitem__(self, key):
dict.__delitem__(self, key)
self._list.remove(key)
def pop(self, key, *default):
present = key in self
value = dict.pop(self, key, *default)
if present:
self._list.remove(key)
return value
def popitem(self):
item = dict.popitem(self)
self._list.remove(item[0])
return item
class OrderedSet(set):
def __init__(self, d=None):
set.__init__(self)
self._list = []
if d is not None:
self._list = unique_list(d)
set.update(self, self._list)
else:
self._list = []
def add(self, element):
if element not in self:
self._list.append(element)
set.add(self, element)
def remove(self, element):
set.remove(self, element)
self._list.remove(element)
def insert(self, pos, element):
if element not in self:
self._list.insert(pos, element)
set.add(self, element)
def discard(self, element):
if element in self:
self._list.remove(element)
set.remove(self, element)
def clear(self):
set.clear(self)
self._list = []
def __getitem__(self, key):
return self._list[key]
def __iter__(self):
return iter(self._list)
def __add__(self, other):
return self.union(other)
def __repr__(self):
return '%s(%r)' % (self.__class__.__name__, self._list)
__str__ = __repr__
def update(self, iterable):
for e in iterable:
if e not in self:
self._list.append(e)
set.add(self, e)
return self
__ior__ = update
def union(self, other):
result = self.__class__(self)
result.update(other)
return result
__or__ = union
def intersection(self, other):
other = set(other)
return self.__class__(a for a in self if a in other)
__and__ = intersection
def symmetric_difference(self, other):
other = set(other)
result = self.__class__(a for a in self if a not in other)
result.update(a for a in other if a not in self)
return result
__xor__ = symmetric_difference
def difference(self, other):
other = set(other)
return self.__class__(a for a in self if a not in other)
__sub__ = difference
def intersection_update(self, other):
other = set(other)
set.intersection_update(self, other)
self._list = [a for a in self._list if a in other]
return self
__iand__ = intersection_update
def symmetric_difference_update(self, other):
set.symmetric_difference_update(self, other)
self._list = [a for a in self._list if a in self]
self._list += [a for a in other._list if a in self]
return self
__ixor__ = symmetric_difference_update
def difference_update(self, other):
set.difference_update(self, other)
self._list = [a for a in self._list if a in self]
return self
__isub__ = difference_update
class IdentitySet(object):
"""A set that considers only object id() for uniqueness.
This strategy has edge cases for builtin types- it's possible to have
two 'foo' strings in one of these sets, for example. Use sparingly.
"""
_working_set = set
def __init__(self, iterable=None):
self._members = dict()
if iterable:
for o in iterable:
self.add(o)
def add(self, value):
self._members[id(value)] = value
def __contains__(self, value):
return id(value) in self._members
def remove(self, value):
del self._members[id(value)]
def discard(self, value):
try:
self.remove(value)
except KeyError:
pass
def pop(self):
try:
pair = self._members.popitem()
return pair[1]
except KeyError:
raise KeyError('pop from an empty set')
def clear(self):
self._members.clear()
def __cmp__(self, other):
raise TypeError('cannot compare sets using cmp()')
def __eq__(self, other):
if isinstance(other, IdentitySet):
return self._members == other._members
else:
return False
def __ne__(self, other):
if isinstance(other, IdentitySet):
return self._members != other._members
else:
return True
def issubset(self, iterable):
other = type(self)(iterable)
if len(self) > len(other):
return False
for m in itertools_filterfalse(other._members.__contains__,
iter(self._members.keys())):
return False
return True
def __le__(self, other):
if not isinstance(other, IdentitySet):
return NotImplemented
return self.issubset(other)
def __lt__(self, other):
if not isinstance(other, IdentitySet):
return NotImplemented
return len(self) < len(other) and self.issubset(other)
def issuperset(self, iterable):
other = type(self)(iterable)
if len(self) < len(other):
return False
for m in itertools_filterfalse(self._members.__contains__,
iter(other._members.keys())):
return False
return True
def __ge__(self, other):
if not isinstance(other, IdentitySet):
return NotImplemented
return self.issuperset(other)
def __gt__(self, other):
if not isinstance(other, IdentitySet):
return NotImplemented
return len(self) > len(other) and self.issuperset(other)
def union(self, iterable):
result = type(self)()
# testlib.pragma exempt:__hash__
members = self._member_id_tuples()
other = _iter_id(iterable)
result._members.update(self._working_set(members).union(other))
return result
def __or__(self, other):
if not isinstance(other, IdentitySet):
return NotImplemented
return self.union(other)
def update(self, iterable):
self._members = self.union(iterable)._members
def __ior__(self, other):
if not isinstance(other, IdentitySet):
return NotImplemented
self.update(other)
return self
def difference(self, iterable):
result = type(self)()
# testlib.pragma exempt:__hash__
members = self._member_id_tuples()
other = _iter_id(iterable)
result._members.update(self._working_set(members).difference(other))
return result
def __sub__(self, other):
if not isinstance(other, IdentitySet):
return NotImplemented
return self.difference(other)
def difference_update(self, iterable):
self._members = self.difference(iterable)._members
def __isub__(self, other):
if not isinstance(other, IdentitySet):
return NotImplemented
self.difference_update(other)
return self
def intersection(self, iterable):
result = type(self)()
# testlib.pragma exempt:__hash__
members = self._member_id_tuples()
other = _iter_id(iterable)
result._members.update(self._working_set(members).intersection(other))
return result
def __and__(self, other):
if not isinstance(other, IdentitySet):
return NotImplemented
return self.intersection(other)
def intersection_update(self, iterable):
self._members = self.intersection(iterable)._members
def __iand__(self, other):
if not isinstance(other, IdentitySet):
return NotImplemented
self.intersection_update(other)
return self
def symmetric_difference(self, iterable):
result = type(self)()
# testlib.pragma exempt:__hash__
members = self._member_id_tuples()
other = _iter_id(iterable)
result._members.update(
self._working_set(members).symmetric_difference(other))
return result
def _member_id_tuples(self):
return ((id(v), v) for v in self._members.values())
def __xor__(self, other):
if not isinstance(other, IdentitySet):
return NotImplemented
return self.symmetric_difference(other)
def symmetric_difference_update(self, iterable):
self._members = self.symmetric_difference(iterable)._members
def __ixor__(self, other):
if not isinstance(other, IdentitySet):
return NotImplemented
self.symmetric_difference(other)
return self
def copy(self):
return type(self)(iter(self._members.values()))
__copy__ = copy
def __len__(self):
return len(self._members)
def __iter__(self):
return iter(self._members.values())
def __hash__(self):
raise TypeError('set objects are unhashable')
def __repr__(self):
return '%s(%r)' % (type(self).__name__, list(self._members.values()))
class WeakSequence(object):
def __init__(self, __elements=()):
self._storage = [
weakref.ref(element, self._remove) for element in __elements
]
def append(self, item):
self._storage.append(weakref.ref(item, self._remove))
def _remove(self, ref):
self._storage.remove(ref)
def __len__(self):
return len(self._storage)
def __iter__(self):
return (obj for obj in
(ref() for ref in self._storage) if obj is not None)
def __getitem__(self, index):
try:
obj = self._storage[index]
except KeyError:
raise IndexError("Index %s out of range" % index)
else:
return obj()
class OrderedIdentitySet(IdentitySet):
class _working_set(OrderedSet):
# a testing pragma: exempt the OIDS working set from the test suite's
# "never call the user's __hash__" assertions. this is a big hammer,
# but it's safe here: IDS operates on (id, instance) tuples in the
# working set.
__sa_hash_exempt__ = True
def __init__(self, iterable=None):
IdentitySet.__init__(self)
self._members = OrderedDict()
if iterable:
for o in iterable:
self.add(o)
class PopulateDict(dict):
"""A dict which populates missing values via a creation function.
Note the creation function takes a key, unlike
collections.defaultdict.
"""
def __init__(self, creator):
self.creator = creator
def __missing__(self, key):
self[key] = val = self.creator(key)
return val
# Define collections that are capable of storing
# ColumnElement objects as hashable keys/elements.
# At this point, these are mostly historical, things
# used to be more complicated.
column_set = set
column_dict = dict
ordered_column_set = OrderedSet
populate_column_dict = PopulateDict
_getters = PopulateDict(operator.itemgetter)
_property_getters = PopulateDict(
lambda idx: property(operator.itemgetter(idx)))
def unique_list(seq, hashfunc=None):
seen = set()
seen_add = seen.add
if not hashfunc:
return [x for x in seq
if x not in seen
and not seen_add(x)]
else:
return [x for x in seq
if hashfunc(x) not in seen
and not seen_add(hashfunc(x))]
class UniqueAppender(object):
"""Appends items to a collection ensuring uniqueness.
Additional appends() of the same object are ignored. Membership is
determined by identity (``is a``) not equality (``==``).
"""
def __init__(self, data, via=None):
self.data = data
self._unique = {}
if via:
self._data_appender = getattr(data, via)
elif hasattr(data, 'append'):
self._data_appender = data.append
elif hasattr(data, 'add'):
self._data_appender = data.add
def append(self, item):
id_ = id(item)
if id_ not in self._unique:
self._data_appender(item)
self._unique[id_] = True
def __iter__(self):
return iter(self.data)
def coerce_generator_arg(arg):
if len(arg) == 1 and isinstance(arg[0], types.GeneratorType):
return list(arg[0])
else:
return arg
def to_list(x, default=None):
if x is None:
return default
if not isinstance(x, collections.Iterable) or \
isinstance(x, string_types + binary_types):
return [x]
elif isinstance(x, list):
return x
else:
return list(x)
def has_intersection(set_, iterable):
"""return True if any items of set_ are present in iterable.
Goes through special effort to ensure __hash__ is not called
on items in iterable that don't support it.
"""
# TODO: optimize, write in C, etc.
return bool(
set_.intersection([i for i in iterable if i.__hash__])
)
def to_set(x):
if x is None:
return set()
if not isinstance(x, set):
return set(to_list(x))
else:
return x
def to_column_set(x):
if x is None:
return column_set()
if not isinstance(x, column_set):
return column_set(to_list(x))
else:
return x
def update_copy(d, _new=None, **kw):
"""Copy the given dict and update with the given values."""
d = d.copy()
if _new:
d.update(_new)
d.update(**kw)
return d
def flatten_iterator(x):
"""Given an iterator of which further sub-elements may also be
iterators, flatten the sub-elements into a single iterator.
"""
for elem in x:
if not isinstance(elem, str) and hasattr(elem, '__iter__'):
for y in flatten_iterator(elem):
yield y
else:
yield elem
class LRUCache(dict):
"""Dictionary with 'squishy' removal of least
recently used items.
Note that either get() or [] should be used here, but
generally its not safe to do an "in" check first as the dictionary
can change subsequent to that call.
"""
def __init__(self, capacity=100, threshold=.5):
self.capacity = capacity
self.threshold = threshold
self._counter = 0
self._mutex = threading.Lock()
def _inc_counter(self):
self._counter += 1
return self._counter
def get(self, key, default=None):
item = dict.get(self, key, default)
if item is not default:
item[2] = self._inc_counter()
return item[1]
else:
return default
def __getitem__(self, key):
item = dict.__getitem__(self, key)
item[2] = self._inc_counter()
return item[1]
def values(self):
return [i[1] for i in dict.values(self)]
def setdefault(self, key, value):
if key in self:
return self[key]
else:
self[key] = value
return value
def __setitem__(self, key, value):
item = dict.get(self, key)
if item is None:
item = [key, value, self._inc_counter()]
dict.__setitem__(self, key, item)
else:
item[1] = value
self._manage_size()
def _manage_size(self):
if not self._mutex.acquire(False):
return
try:
while len(self) > self.capacity + self.capacity * self.threshold:
by_counter = sorted(dict.values(self),
key=operator.itemgetter(2),
reverse=True)
for item in by_counter[self.capacity:]:
try:
del self[item[0]]
except KeyError:
# deleted elsewhere; skip
continue
finally:
self._mutex.release()
_lw_tuples = LRUCache(100)
def lightweight_named_tuple(name, fields):
hash_ = (name, ) + tuple(fields)
tp_cls = _lw_tuples.get(hash_)
if tp_cls:
return tp_cls
tp_cls = type(
name, (_LW,),
dict([
(field, _property_getters[idx])
for idx, field in enumerate(fields) if field is not None
] + [('__slots__', ())])
)
tp_cls._real_fields = fields
tp_cls._fields = tuple([f for f in fields if f is not None])
_lw_tuples[hash_] = tp_cls
return tp_cls
class ScopedRegistry(object):
"""A Registry that can store one or multiple instances of a single
class on the basis of a "scope" function.
The object implements ``__call__`` as the "getter", so by
calling ``myregistry()`` the contained object is returned
for the current scope.
:param createfunc:
a callable that returns a new object to be placed in the registry
:param scopefunc:
a callable that will return a key to store/retrieve an object.
"""
def __init__(self, createfunc, scopefunc):
"""Construct a new :class:`.ScopedRegistry`.
:param createfunc: A creation function that will generate
a new value for the current scope, if none is present.
:param scopefunc: A function that returns a hashable
token representing the current scope (such as, current
thread identifier).
"""
self.createfunc = createfunc
self.scopefunc = scopefunc
self.registry = {}
def __call__(self):
key = self.scopefunc()
try:
return self.registry[key]
except KeyError:
return self.registry.setdefault(key, self.createfunc())
def has(self):
"""Return True if an object is present in the current scope."""
return self.scopefunc() in self.registry
def set(self, obj):
"""Set the value for the current scope."""
self.registry[self.scopefunc()] = obj
def clear(self):
"""Clear the current scope, if any."""
try:
del self.registry[self.scopefunc()]
except KeyError:
pass
class ThreadLocalRegistry(ScopedRegistry):
"""A :class:`.ScopedRegistry` that uses a ``threading.local()``
variable for storage.
"""
def __init__(self, createfunc):
self.createfunc = createfunc
self.registry = threading.local()
def __call__(self):
try:
return self.registry.value
except AttributeError:
val = self.registry.value = self.createfunc()
return val
def has(self):
return hasattr(self.registry, "value")
def set(self, obj):
self.registry.value = obj
def clear(self):
try:
del self.registry.value
except AttributeError:
pass
def _iter_id(iterable):
"""Generator: ((id(o), o) for o in iterable)."""
for item in iterable:
yield id(item), item
|