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//usr/lib64/python2.7/site-packages/sqlalchemy/util/_collections.py

# util/_collections.py
# Copyright (C) 2005-2020 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` 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.

.. 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.

"""

_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=()):
        # 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):
    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

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 _iter_id(iterable):
    """Generator: ((id(o), o) for o in iterable)."""

for item in iterable:
        yield id(item), item

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:]