File Explorer

/proc/self/root/proc/thread-self/root/proc/self/root/proc/self/root/lib64/python3.9

This explorer reads the filesystem of the server it runs on, so /workspace/user isn't present here. Browsing and the terminal still work against this server's own disk from /.

weakref.py21.1 KB · 676 lines
"""Weak reference support for Python. This module is an implementation of PEP 205: https://www.python.org/dev/peps/pep-0205/""" # Naming convention: Variables named "wr" are weak reference objects;# they are called this instead of "ref" to avoid name collisions with# the module-global ref() function imported from _weakref. from _weakref import (     getweakrefcount,     getweakrefs,     ref,     proxy,     CallableProxyType,     ProxyType,     ReferenceType,     _remove_dead_weakref) from _weakrefset import WeakSet, _IterationGuard import _collections_abc  # Import after _weakref to avoid circular import.import sysimport itertools ProxyTypes = (ProxyType, CallableProxyType) __all__ = ["ref", "proxy", "getweakrefcount", "getweakrefs",           "WeakKeyDictionary", "ReferenceType", "ProxyType",           "CallableProxyType", "ProxyTypes", "WeakValueDictionary",           "WeakSet", "WeakMethod", "finalize"]  _collections_abc.Set.register(WeakSet)_collections_abc.MutableSet.register(WeakSet) class WeakMethod(ref):    """    A custom `weakref.ref` subclass which simulates a weak reference to    a bound method, working around the lifetime problem of bound methods.    """     __slots__ = "_func_ref", "_meth_type", "_alive", "__weakref__"     def __new__(cls, meth, callback=None):        try:            obj = meth.__self__            func = meth.__func__        except AttributeError:            raise TypeError("argument should be a bound method, not {}"                            .format(type(meth))) from None        def _cb(arg):            # The self-weakref trick is needed to avoid creating a reference            # cycle.            self = self_wr()            if self._alive:                self._alive = False                if callback is not None:                    callback(self)        self = ref.__new__(cls, obj, _cb)        self._func_ref = ref(func, _cb)        self._meth_type = type(meth)        self._alive = True        self_wr = ref(self)        return self     def __call__(self):        obj = super().__call__()        func = self._func_ref()        if obj is None or func is None:            return None        return self._meth_type(func, obj)     def __eq__(self, other):        if isinstance(other, WeakMethod):            if not self._alive or not other._alive:                return self is other            return ref.__eq__(self, other) and self._func_ref == other._func_ref        return NotImplemented     def __ne__(self, other):        if isinstance(other, WeakMethod):            if not self._alive or not other._alive:                return self is not other            return ref.__ne__(self, other) or self._func_ref != other._func_ref        return NotImplemented     __hash__ = ref.__hash__  class WeakValueDictionary(_collections_abc.MutableMapping):    """Mapping class that references values weakly.     Entries in the dictionary will be discarded when no strong    reference to the value exists anymore    """    # We inherit the constructor without worrying about the input    # dictionary; since it uses our .update() method, we get the right    # checks (if the other dictionary is a WeakValueDictionary,    # objects are unwrapped on the way out, and we always wrap on the    # way in).     def __init__(self, other=(), /, **kw):        def remove(wr, selfref=ref(self), _atomic_removal=_remove_dead_weakref):            self = selfref()            if self is not None:                if self._iterating:                    self._pending_removals.append(wr.key)                else:                    # Atomic removal is necessary since this function                    # can be called asynchronously by the GC                    _atomic_removal(self.data, wr.key)        self._remove = remove        # A list of keys to be removed        self._pending_removals = []        self._iterating = set()        self.data = {}        self.update(other, **kw)     def _commit_removals(self, _atomic_removal=_remove_dead_weakref):        pop = self._pending_removals.pop        d = self.data        # We shouldn't encounter any KeyError, because this method should        # always be called *before* mutating the dict.        while True:            try:                key = pop()            except IndexError:                return            _atomic_removal(d, key)     def __getitem__(self, key):        if self._pending_removals:            self._commit_removals()        o = self.data[key]()        if o is None:            raise KeyError(key)        else:            return o     def __delitem__(self, key):        if self._pending_removals:            self._commit_removals()        del self.data[key]     def __len__(self):        if self._pending_removals:            self._commit_removals()        return len(self.data)     def __contains__(self, key):        if self._pending_removals:            self._commit_removals()        try:            o = self.data[key]()        except KeyError:            return False        return o is not None     def __repr__(self):        return "<%s at %#x>" % (self.__class__.__name__, id(self))     def __setitem__(self, key, value):        if self._pending_removals:            self._commit_removals()        self.data[key] = KeyedRef(value, self._remove, key)     def copy(self):        if self._pending_removals:            self._commit_removals()        new = WeakValueDictionary()        with _IterationGuard(self):            for key, wr in self.data.items():                o = wr()                if o is not None:                    new[key] = o        return new     __copy__ = copy     def __deepcopy__(self, memo):        from copy import deepcopy        if self._pending_removals:            self._commit_removals()        new = self.__class__()        with _IterationGuard(self):            for key, wr in self.data.items():                o = wr()                if o is not None:                    new[deepcopy(key, memo)] = o        return new     def get(self, key, default=None):        if self._pending_removals:            self._commit_removals()        try:            wr = self.data[key]        except KeyError:            return default        else:            o = wr()            if o is None:                # This should only happen                return default            else:                return o     def items(self):        if self._pending_removals:            self._commit_removals()        with _IterationGuard(self):            for k, wr in self.data.items():                v = wr()                if v is not None:                    yield k, v     def keys(self):        if self._pending_removals:            self._commit_removals()        with _IterationGuard(self):            for k, wr in self.data.items():                if wr() is not None:                    yield k     __iter__ = keys     def itervaluerefs(self):        """Return an iterator that yields the weak references to the values.         The references are not guaranteed to be 'live' at the time        they are used, so the result of calling the references needs        to be checked before being used.  This can be used to avoid        creating references that will cause the garbage collector to        keep the values around longer than needed.         """        if self._pending_removals:            self._commit_removals()        with _IterationGuard(self):            yield from self.data.values()     def values(self):        if self._pending_removals:            self._commit_removals()        with _IterationGuard(self):            for wr in self.data.values():                obj = wr()                if obj is not None:                    yield obj     def popitem(self):        if self._pending_removals:            self._commit_removals()        while True:            key, wr = self.data.popitem()            o = wr()            if o is not None:                return key, o     def pop(self, key, *args):        if self._pending_removals:            self._commit_removals()        try:            o = self.data.pop(key)()        except KeyError:            o = None        if o is None:            if args:                return args[0]            else:                raise KeyError(key)        else:            return o     def setdefault(self, key, default=None):        try:            o = self.data[key]()        except KeyError:            o = None        if o is None:            if self._pending_removals:                self._commit_removals()            self.data[key] = KeyedRef(default, self._remove, key)            return default        else:            return o     def update(self, other=None, /, **kwargs):        if self._pending_removals:            self._commit_removals()        d = self.data        if other is not None:            if not hasattr(other, "items"):                other = dict(other)            for key, o in other.items():                d[key] = KeyedRef(o, self._remove, key)        for key, o in kwargs.items():            d[key] = KeyedRef(o, self._remove, key)     def valuerefs(self):        """Return a list of weak references to the values.         The references are not guaranteed to be 'live' at the time        they are used, so the result of calling the references needs        to be checked before being used.  This can be used to avoid        creating references that will cause the garbage collector to        keep the values around longer than needed.         """        if self._pending_removals:            self._commit_removals()        return list(self.data.values())     def __ior__(self, other):        self.update(other)        return self     def __or__(self, other):        if isinstance(other, _collections_abc.Mapping):            c = self.copy()            c.update(other)            return c        return NotImplemented     def __ror__(self, other):        if isinstance(other, _collections_abc.Mapping):            c = self.__class__()            c.update(other)            c.update(self)            return c        return NotImplemented  class KeyedRef(ref):    """Specialized reference that includes a key corresponding to the value.     This is used in the WeakValueDictionary to avoid having to create    a function object for each key stored in the mapping.  A shared    callback object can use the 'key' attribute of a KeyedRef instead    of getting a reference to the key from an enclosing scope.     """     __slots__ = "key",     def __new__(type, ob, callback, key):        self = ref.__new__(type, ob, callback)        self.key = key        return self     def __init__(self, ob, callback, key):        super().__init__(ob, callback)  class WeakKeyDictionary(_collections_abc.MutableMapping):    """ Mapping class that references keys weakly.     Entries in the dictionary will be discarded when there is no    longer a strong reference to the key. This can be used to    associate additional data with an object owned by other parts of    an application without adding attributes to those objects. This    can be especially useful with objects that override attribute    accesses.    """     def __init__(self, dict=None):        self.data = {}        def remove(k, selfref=ref(self)):            self = selfref()            if self is not None:                if self._iterating:                    self._pending_removals.append(k)                else:                    try:                        del self.data[k]                    except KeyError:                        pass        self._remove = remove        # A list of dead weakrefs (keys to be removed)        self._pending_removals = []        self._iterating = set()        self._dirty_len = False        if dict is not None:            self.update(dict)     def _commit_removals(self):        # NOTE: We don't need to call this method before mutating the dict,        # because a dead weakref never compares equal to a live weakref,        # even if they happened to refer to equal objects.        # However, it means keys may already have been removed.        pop = self._pending_removals.pop        d = self.data        while True:            try:                key = pop()            except IndexError:                return             try:                del d[key]            except KeyError:                pass     def _scrub_removals(self):        d = self.data        self._pending_removals = [k for k in self._pending_removals if k in d]        self._dirty_len = False     def __delitem__(self, key):        self._dirty_len = True        del self.data[ref(key)]     def __getitem__(self, key):        return self.data[ref(key)]     def __len__(self):        if self._dirty_len and self._pending_removals:            # self._pending_removals may still contain keys which were            # explicitly removed, we have to scrub them (see issue #21173).            self._scrub_removals()        return len(self.data) - len(self._pending_removals)     def __repr__(self):        return "<%s at %#x>" % (self.__class__.__name__, id(self))     def __setitem__(self, key, value):        self.data[ref(key, self._remove)] = value     def copy(self):        new = WeakKeyDictionary()        with _IterationGuard(self):            for key, value in self.data.items():                o = key()                if o is not None:                    new[o] = value        return new     __copy__ = copy     def __deepcopy__(self, memo):        from copy import deepcopy        new = self.__class__()        with _IterationGuard(self):            for key, value in self.data.items():                o = key()                if o is not None:                    new[o] = deepcopy(value, memo)        return new     def get(self, key, default=None):        return self.data.get(ref(key),default)     def __contains__(self, key):        try:            wr = ref(key)        except TypeError:            return False        return wr in self.data     def items(self):        with _IterationGuard(self):            for wr, value in self.data.items():                key = wr()                if key is not None:                    yield key, value     def keys(self):        with _IterationGuard(self):            for wr in self.data:                obj = wr()                if obj is not None:                    yield obj     __iter__ = keys     def values(self):        with _IterationGuard(self):            for wr, value in self.data.items():                if wr() is not None:                    yield value     def keyrefs(self):        """Return a list of weak references to the keys.         The references are not guaranteed to be 'live' at the time        they are used, so the result of calling the references needs        to be checked before being used.  This can be used to avoid        creating references that will cause the garbage collector to        keep the keys around longer than needed.         """        return list(self.data)     def popitem(self):        self._dirty_len = True        while True:            key, value = self.data.popitem()            o = key()            if o is not None:                return o, value     def pop(self, key, *args):        self._dirty_len = True        return self.data.pop(ref(key), *args)     def setdefault(self, key, default=None):        return self.data.setdefault(ref(key, self._remove),default)     def update(self, dict=None, /, **kwargs):        d = self.data        if dict is not None:            if not hasattr(dict, "items"):                dict = type({})(dict)            for key, value in dict.items():                d[ref(key, self._remove)] = value        if len(kwargs):            self.update(kwargs)     def __ior__(self, other):        self.update(other)        return self     def __or__(self, other):        if isinstance(other, _collections_abc.Mapping):            c = self.copy()            c.update(other)            return c        return NotImplemented     def __ror__(self, other):        if isinstance(other, _collections_abc.Mapping):            c = self.__class__()            c.update(other)            c.update(self)            return c        return NotImplemented  class finalize:    """Class for finalization of weakrefable objects     finalize(obj, func, *args, **kwargs) returns a callable finalizer    object which will be called when obj is garbage collected. The    first time the finalizer is called it evaluates func(*arg, **kwargs)    and returns the result. After this the finalizer is dead, and    calling it just returns None.     When the program exits any remaining finalizers for which the    atexit attribute is true will be run in reverse order of creation.    By default atexit is true.    """     # Finalizer objects don't have any state of their own.  They are    # just used as keys to lookup _Info objects in the registry.  This    # ensures that they cannot be part of a ref-cycle.     __slots__ = ()    _registry = {}    _shutdown = False    _index_iter = itertools.count()    _dirty = False    _registered_with_atexit = False     class _Info:        __slots__ = ("weakref", "func", "args", "kwargs", "atexit", "index")     def __init__(self, obj, func, /, *args, **kwargs):        if not self._registered_with_atexit:            # We may register the exit function more than once because            # of a thread race, but that is harmless            import atexit            atexit.register(self._exitfunc)            finalize._registered_with_atexit = True        info = self._Info()        info.weakref = ref(obj, self)        info.func = func        info.args = args        info.kwargs = kwargs or None        info.atexit = True        info.index = next(self._index_iter)        self._registry[self] = info        finalize._dirty = True     def __call__(self, _=None):        """If alive then mark as dead and return func(*args, **kwargs);        otherwise return None"""        info = self._registry.pop(self, None)        if info and not self._shutdown:            return info.func(*info.args, **(info.kwargs or {}))     def detach(self):        """If alive then mark as dead and return (obj, func, args, kwargs);        otherwise return None"""        info = self._registry.get(self)        obj = info and info.weakref()        if obj is not None and self._registry.pop(self, None):            return (obj, info.func, info.args, info.kwargs or {})     def peek(self):        """If alive then return (obj, func, args, kwargs);        otherwise return None"""        info = self._registry.get(self)        obj = info and info.weakref()        if obj is not None:            return (obj, info.func, info.args, info.kwargs or {})     @property    def alive(self):        """Whether finalizer is alive"""        return self in self._registry     @property    def atexit(self):        """Whether finalizer should be called at exit"""        info = self._registry.get(self)        return bool(info) and info.atexit     @atexit.setter    def atexit(self, value):        info = self._registry.get(self)        if info:            info.atexit = bool(value)     def __repr__(self):        info = self._registry.get(self)        obj = info and info.weakref()        if obj is None:            return '<%s object at %#x; dead>' % (type(self).__name__, id(self))        else:            return '<%s object at %#x; for %r at %#x>' % \                (type(self).__name__, id(self), type(obj).__name__, id(obj))     @classmethod    def _select_for_exit(cls):        # Return live finalizers marked for exit, oldest first        L = [(f,i) for (f,i) in cls._registry.items() if i.atexit]        L.sort(key=lambda item:item[1].index)        return [f for (f,i) in L]     @classmethod    def _exitfunc(cls):        # At shutdown invoke finalizers for which atexit is true.        # This is called once all other non-daemonic threads have been        # joined.        reenable_gc = False        try:            if cls._registry:                import gc                if gc.isenabled():                    reenable_gc = True                    gc.disable()                pending = None                while True:                    if pending is None or finalize._dirty:                        pending = cls._select_for_exit()                        finalize._dirty = False                    if not pending:                        break                    f = pending.pop()                    try:                        # gc is disabled, so (assuming no daemonic                        # threads) the following is the only line in                        # this function which might trigger creation                        # of a new finalizer                        f()                    except Exception:                        sys.excepthook(*sys.exc_info())                    assert f not in cls._registry        finally:            # prevent any more finalizers from executing during shutdown            finalize._shutdown = True            if reenable_gc:                gc.enable()