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# util/_collections.py
# Copyright (C) 2005-2021 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 operator
import types
import weakref
from .compat import binary_types
from .compat import collections_abc
from .compat import itertools_filterfalse
from .compat import py2k
from .compat import string_types
from .compat import threading
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.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.Query` object's use case.
.. 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()``.
.. 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.
"""
return {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 __dir__(self):
return dir(super(Properties, self)) + [
str(k) for k in self._data.keys()
]
def __add__(self, other):
return list(self) + list(other)
def __setitem__(self, key, obj):
self._data[key] = obj
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, obj):
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, obj)
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.
"""
def __init__(self, iterable=None):
self._members = dict()
if iterable:
self.update(iterable)
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 = self.__class__(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 = self.__class__(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 = self.__class__()
members = self._members
result._members.update(members)
result._members.update((id(obj), obj) for obj in iterable)
return result
def __or__(self, other):
if not isinstance(other, IdentitySet):
return NotImplemented
return self.union(other)
def update(self, iterable):
self._members.update((id(obj), obj) for obj in iterable)
def __ior__(self, other):
if not isinstance(other, IdentitySet):
return NotImplemented
self.update(other)
return self
def difference(self, iterable):
result = self.__class__()
members = self._members
other = {id(obj) for obj in iterable}
result._members.update(
((k, v) for k, v in members.items() if k not in 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 = self.__class__()
members = self._members
other = {id(obj) for obj in iterable}
result._members.update(
(k, v) for k, v in members.items() if k in 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 = self.__class__()
members = self._members
other = {id(obj): obj for obj in iterable}
result._members.update(
((k, v) for k, v in members.items() if k not in other)
)
result._members.update(
((k, v) for k, v in other.items() if k not in members)
)
return result
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=()):
# adapted from weakref.WeakKeyDictionary, prevent reference
# cycles in the collection itself
def _remove(item, selfref=weakref.ref(self)):
self = selfref()
if self is not None:
self._storage.remove(item)
self._remove = _remove
self._storage = [
weakref.ref(element, _remove) for element in __elements
]
def append(self, item):
self._storage.append(weakref.ref(item, self._remove))
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):
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
class WeakPopulateDict(dict):
"""Like PopulateDict, but assumes a self + a method and does not create
a reference cycle.
"""
def __init__(self, creator_method):
self.creator = creator_method.__func__
weakself = creator_method.__self__
self.weakself = weakref.ref(weakself)
def __missing__(self, key):
self[key] = val = self.creator(self.weakself(), 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
_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_abc.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):
r"""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.
"""
__slots__ = "capacity", "threshold", "size_alert", "_counter", "_mutex"
def __init__(self, capacity=100, threshold=0.5, size_alert=None):
self.capacity = capacity
self.threshold = threshold
self.size_alert = size_alert
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()
@property
def size_threshold(self):
return self.capacity + self.capacity * self.threshold
def _manage_size(self):
if not self._mutex.acquire(False):
return
try:
size_alert = bool(self.size_alert)
while len(self) > self.capacity + self.capacity * self.threshold:
if size_alert:
size_alert = False
self.size_alert(self)
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 has_dupes(sequence, target):
"""Given a sequence and search object, return True if there's more
than one, False if zero or one of them.
"""
# compare to .index version below, this version introduces less function
# overhead and is usually the same speed. At 15000 items (way bigger than
# a relationship-bound collection in memory usually is) it begins to
# fall behind the other version only by microseconds.
c = 0
for item in sequence:
if item is target:
c += 1
if c > 1:
return True
return False
# .index version. the two __contains__ calls as well
# as .index() and isinstance() slow this down.
# def has_dupes(sequence, target):
# if target not in sequence:
# return False
# elif not isinstance(sequence, collections_abc.Sequence):
# return False
#
# idx = sequence.index(target)
# return target in sequence[idx + 1:]