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Editing: local.py
import copy import math import operator import typing as t from contextvars import ContextVar from functools import partial from functools import update_wrapper from operator import attrgetter from .wsgi import ClosingIterator if t.TYPE_CHECKING: from _typeshed.wsgi import StartResponse from _typeshed.wsgi import WSGIApplication from _typeshed.wsgi import WSGIEnvironment T = t.TypeVar("T") F = t.TypeVar("F", bound=t.Callable[..., t.Any]) def release_local(local: t.Union["Local", "LocalStack"]) -> None: """Release the data for the current context in a :class:`Local` or :class:`LocalStack` without using a :class:`LocalManager`. This should not be needed for modern use cases, and may be removed in the future. .. versionadded:: 0.6.1 """ local.__release_local__() class Local: """Create a namespace of context-local data. This wraps a :class:`ContextVar` containing a :class:`dict` value. This may incur a performance penalty compared to using individual context vars, as it has to copy data to avoid mutating the dict between nested contexts. :param context_var: The :class:`~contextvars.ContextVar` to use as storage for this local. If not given, one will be created. Context vars not created at the global scope may interfere with garbage collection. .. versionchanged:: 2.0 Uses ``ContextVar`` instead of a custom storage implementation. """ __slots__ = ("__storage",) def __init__( self, context_var: t.Optional[ContextVar[t.Dict[str, t.Any]]] = None ) -> None: if context_var is None: # A ContextVar not created at global scope interferes with # Python's garbage collection. However, a local only makes # sense defined at the global scope as well, in which case # the GC issue doesn't seem relevant. context_var = ContextVar(f"werkzeug.Local<{id(self)}>.storage") object.__setattr__(self, "_Local__storage", context_var) def __iter__(self) -> t.Iterator[t.Tuple[str, t.Any]]: return iter(self.__storage.get({}).items()) def __call__( self, name: str, *, unbound_message: t.Optional[str] = None ) -> "LocalProxy": """Create a :class:`LocalProxy` that access an attribute on this local namespace. :param name: Proxy this attribute. :param unbound_message: The error message that the proxy will show if the attribute isn't set. """ return LocalProxy(self, name, unbound_message=unbound_message) def __release_local__(self) -> None: self.__storage.set({}) def __getattr__(self, name: str) -> t.Any: values = self.__storage.get({}) if name in values: return values[name] raise AttributeError(name) def __setattr__(self, name: str, value: t.Any) -> None: values = self.__storage.get({}).copy() values[name] = value self.__storage.set(values) def __delattr__(self, name: str) -> None: values = self.__storage.get({}) if name in values: values = values.copy() del values[name] self.__storage.set(values) else: raise AttributeError(name) class LocalStack(t.Generic[T]): """Create a stack of context-local data. This wraps a :class:`ContextVar` containing a :class:`list` value. This may incur a performance penalty compared to using individual context vars, as it has to copy data to avoid mutating the list between nested contexts. :param context_var: The :class:`~contextvars.ContextVar` to use as storage for this local. If not given, one will be created. Context vars not created at the global scope may interfere with garbage collection. .. versionchanged:: 2.0 Uses ``ContextVar`` instead of a custom storage implementation. .. versionadded:: 0.6.1 """ __slots__ = ("_storage",) def __init__(self, context_var: t.Optional[ContextVar[t.List[T]]] = None) -> None: if context_var is None: # A ContextVar not created at global scope interferes with # Python's garbage collection. However, a local only makes # sense defined at the global scope as well, in which case # the GC issue doesn't seem relevant. context_var = ContextVar(f"werkzeug.LocalStack<{id(self)}>.storage") self._storage = context_var def __release_local__(self) -> None: self._storage.set([]) def push(self, obj: T) -> t.List[T]: """Add a new item to the top of the stack.""" stack = self._storage.get([]).copy() stack.append(obj) self._storage.set(stack) return stack def pop(self) -> t.Optional[T]: """Remove the top item from the stack and return it. If the stack is empty, return ``None``. """ stack = self._storage.get([]) if len(stack) == 0: return None rv = stack[-1] self._storage.set(stack[:-1]) return rv @property def top(self) -> t.Optional[T]: """The topmost item on the stack. If the stack is empty, `None` is returned. """ stack = self._storage.get([]) if len(stack) == 0: return None return stack[-1] def __call__( self, name: t.Optional[str] = None, *, unbound_message: t.Optional[str] = None ) -> "LocalProxy": """Create a :class:`LocalProxy` that accesses the top of this local stack. :param name: If given, the proxy access this attribute of the top item, rather than the item itself. :param unbound_message: The error message that the proxy will show if the stack is empty. """ return LocalProxy(self, name, unbound_message=unbound_message) class LocalManager: """Manage releasing the data for the current context in one or more :class:`Local` and :class:`LocalStack` objects. This should not be needed for modern use cases, and may be removed in the future. :param locals: A local or list of locals to manage. .. versionchanged:: 2.0 ``ident_func`` is deprecated and will be removed in Werkzeug 2.1. .. versionchanged:: 0.7 The ``ident_func`` parameter was added. .. versionchanged:: 0.6.1 The :func:`release_local` function can be used instead of a manager. """ __slots__ = ("locals",) def __init__( self, locals: t.Optional[ t.Union[Local, LocalStack, t.Iterable[t.Union[Local, LocalStack]]] ] = None, ) -> None: if locals is None: self.locals = [] elif isinstance(locals, Local): self.locals = [locals] else: self.locals = list(locals) # type: ignore[arg-type] def cleanup(self) -> None: """Release the data in the locals for this context. Call this at the end of each request or use :meth:`make_middleware`. """ for local in self.locals: release_local(local) def make_middleware(self, app: "WSGIApplication") -> "WSGIApplication": """Wrap a WSGI application so that local data is released automatically after the response has been sent for a request. """ def application( environ: "WSGIEnvironment", start_response: "StartResponse" ) -> t.Iterable[bytes]: return ClosingIterator(app(environ, start_response), self.cleanup) return application def middleware(self, func: "WSGIApplication") -> "WSGIApplication": """Like :meth:`make_middleware` but used as a decorator on the WSGI application function. .. code-block:: python @manager.middleware def application(environ, start_response): ... """ return update_wrapper(self.make_middleware(func), func) def __repr__(self) -> str: return f"<{type(self).__name__} storages: {len(self.locals)}>" class _ProxyLookup: """Descriptor that handles proxied attribute lookup for :class:`LocalProxy`. :param f: The built-in function this attribute is accessed through. Instead of looking up the special method, the function call is redone on the object. :param fallback: Return this function if the proxy is unbound instead of raising a :exc:`RuntimeError`. :param is_attr: This proxied name is an attribute, not a function. Call the fallback immediately to get the value. :param class_value: Value to return when accessed from the ``LocalProxy`` class directly. Used for ``__doc__`` so building docs still works. """ __slots__ = ("bind_f", "fallback", "is_attr", "class_value", "name") def __init__( self, f: t.Optional[t.Callable] = None, fallback: t.Optional[t.Callable] = None, class_value: t.Optional[t.Any] = None, is_attr: bool = False, ) -> None: bind_f: t.Optional[t.Callable[["LocalProxy", t.Any], t.Callable]] if hasattr(f, "__get__"): # A Python function, can be turned into a bound method. def bind_f(instance: "LocalProxy", obj: t.Any) -> t.Callable: return f.__get__(obj, type(obj)) # type: ignore elif f is not None: # A C function, use partial to bind the first argument. def bind_f(instance: "LocalProxy", obj: t.Any) -> t.Callable: return partial(f, obj) # type: ignore else: # Use getattr, which will produce a bound method. bind_f = None self.bind_f = bind_f self.fallback = fallback self.class_value = class_value self.is_attr = is_attr def __set_name__(self, owner: "LocalProxy", name: str) -> None: self.name = name def __get__(self, instance: "LocalProxy", owner: t.Optional[type] = None) -> t.Any: if instance is None: if self.class_value is not None: return self.class_value return self try: obj = instance._get_current_object() # type: ignore[misc] except RuntimeError: if self.fallback is None: raise fallback = self.fallback.__get__(instance, owner) if self.is_attr: # __class__ and __doc__ are attributes, not methods. # Call the fallback to get the value. return fallback() return fallback if self.bind_f is not None: return self.bind_f(instance, obj) return getattr(obj, self.name) def __repr__(self) -> str: return f"proxy {self.name}" def __call__(self, instance: "LocalProxy", *args: t.Any, **kwargs: t.Any) -> t.Any: """Support calling unbound methods from the class. For example, this happens with ``copy.copy``, which does ``type(x).__copy__(x)``. ``type(x)`` can't be proxied, so it returns the proxy type and descriptor. """ return self.__get__(instance, type(instance))(*args, **kwargs) class _ProxyIOp(_ProxyLookup): """Look up an augmented assignment method on a proxied object. The method is wrapped to return the proxy instead of the object. """ __slots__ = () def __init__( self, f: t.Optional[t.Callable] = None, fallback: t.Optional[t.Callable] = None ) -> None: super().__init__(f, fallback) def bind_f(instance: "LocalProxy", obj: t.Any) -> t.Callable: def i_op(self: t.Any, other: t.Any) -> "LocalProxy": f(self, other) # type: ignore return instance return i_op.__get__(obj, type(obj)) # type: ignore self.bind_f = bind_f def _l_to_r_op(op: F) -> F: """Swap the argument order to turn an l-op into an r-op.""" def r_op(obj: t.Any, other: t.Any) -> t.Any: return op(other, obj) return t.cast(F, r_op) def _identity(o: T) -> T: return o class LocalProxy(t.Generic[T]): """A proxy to the object bound to a context-local object. All operations on the proxy are forwarded to the bound object. If no object is bound, a ``RuntimeError`` is raised. :param local: The context-local object that provides the proxied object. :param name: Proxy this attribute from the proxied object. :param unbound_message: The error message to show if the context-local object is unbound. Proxy a :class:`~contextvars.ContextVar` to make it easier to access. Pass a name to proxy that attribute. .. code-block:: python _request_var = ContextVar("request") request = LocalProxy(_request_var) session = LocalProxy(_request_var, "session") Proxy an attribute on a :class:`Local` namespace by calling the local with the attribute name: .. code-block:: python data = Local() user = data("user") Proxy the top item on a :class:`LocalStack` by calling the local. Pass a name to proxy that attribute. .. code-block:: app_stack = LocalStack() current_app = app_stack() g = app_stack("g") Pass a function to proxy the return value from that function. This was previously used to access attributes of local objects before that was supported directly. .. code-block:: python session = LocalProxy(lambda: request.session) ``__repr__`` and ``__class__`` are proxied, so ``repr(x)`` and ``isinstance(x, cls)`` will look like the proxied object. Use ``issubclass(type(x), LocalProxy)`` to check if an object is a proxy. .. code-block:: python repr(user) # <User admin> isinstance(user, User) # True issubclass(type(user), LocalProxy) # True .. versionchanged:: 2.2.2 ``__wrapped__`` is set when wrapping an object, not only when wrapping a function, to prevent doctest from failing. .. versionchanged:: 2.2 Can proxy a ``ContextVar`` or ``LocalStack`` directly. .. versionchanged:: 2.2 The ``name`` parameter can be used with any proxied object, not only ``Local``. .. versionchanged:: 2.2 Added the ``unbound_message`` parameter. .. versionchanged:: 2.0 Updated proxied attributes and methods to reflect the current data model. .. versionchanged:: 0.6.1 The class can be instantiated with a callable. """ __slots__ = ("__wrapped", "_get_current_object") _get_current_object: t.Callable[[], T] """Return the current object this proxy is bound to. If the proxy is unbound, this raises a ``RuntimeError``. This should be used if you need to pass the object to something that doesn't understand the proxy. It can also be useful for performance if you are accessing the object multiple times in a function, rather than going through the proxy multiple times. """ def __init__( self, local: t.Union[ContextVar[T], Local, LocalStack[T], t.Callable[[], T]], name: t.Optional[str] = None, *, unbound_message: t.Optional[str] = None, ) -> None: if name is None: get_name = _identity else: get_name = attrgetter(name) # type: ignore[assignment] if unbound_message is None: unbound_message = "object is not bound" if isinstance(local, Local): if name is None: raise TypeError("'name' is required when proxying a 'Local' object.") def _get_current_object() -> T: try: return get_name(local) # type: ignore[return-value] except AttributeError: raise RuntimeError(unbound_message) from None elif isinstance(local, LocalStack): def _get_current_object() -> T: obj = local.top # type: ignore[union-attr] if obj is None: raise RuntimeError(unbound_message) return get_name(obj) elif isinstance(local, ContextVar): def _get_current_object() -> T: try: obj = local.get() # type: ignore[union-attr] except LookupError: raise RuntimeError(unbound_message) from None return get_name(obj) elif callable(local): def _get_current_object() -> T: return get_name(local()) # type: ignore else: raise TypeError(f"Don't know how to proxy '{type(local)}'.") object.__setattr__(self, "_LocalProxy__wrapped", local) object.__setattr__(self, "_get_current_object", _get_current_object) __doc__ = _ProxyLookup( # type: ignore class_value=__doc__, fallback=lambda self: type(self).__doc__, is_attr=True ) __wrapped__ = _ProxyLookup( fallback=lambda self: self._LocalProxy__wrapped, is_attr=True ) # __del__ should only delete the proxy __repr__ = _ProxyLookup( # type: ignore repr, fallback=lambda self: f"<{type(self).__name__} unbound>" ) __str__ = _ProxyLookup(str) # type: ignore __bytes__ = _ProxyLookup(bytes) __format__ = _ProxyLookup() # type: ignore __lt__ = _ProxyLookup(operator.lt) __le__ = _ProxyLookup(operator.le) __eq__ = _ProxyLookup(operator.eq) # type: ignore __ne__ = _ProxyLookup(operator.ne) # type: ignore __gt__ = _ProxyLookup(operator.gt) __ge__ = _ProxyLookup(operator.ge) __hash__ = _ProxyLookup(hash) # type: ignore __bool__ = _ProxyLookup(bool, fallback=lambda self: False) __getattr__ = _ProxyLookup(getattr) # __getattribute__ triggered through __getattr__ __setattr__ = _ProxyLookup(setattr) # type: ignore __delattr__ = _ProxyLookup(delattr) # type: ignore __dir__ = _ProxyLookup(dir, fallback=lambda self: []) # type: ignore # __get__ (proxying descriptor not supported) # __set__ (descriptor) # __delete__ (descriptor) # __set_name__ (descriptor) # __objclass__ (descriptor) # __slots__ used by proxy itself # __dict__ (__getattr__) # __weakref__ (__getattr__) # __init_subclass__ (proxying metaclass not supported) # __prepare__ (metaclass) __class__ = _ProxyLookup( fallback=lambda self: type(self), is_attr=True ) # type: ignore __instancecheck__ = _ProxyLookup(lambda self, other: isinstance(other, self)) __subclasscheck__ = _ProxyLookup(lambda self, other: issubclass(other, self)) # __class_getitem__ triggered through __getitem__ __call__ = _ProxyLookup(lambda self, *args, **kwargs: self(*args, **kwargs)) __len__ = _ProxyLookup(len) __length_hint__ = _ProxyLookup(operator.length_hint) __getitem__ = _ProxyLookup(operator.getitem) __setitem__ = _ProxyLookup(operator.setitem) __delitem__ = _ProxyLookup(operator.delitem) # __missing__ triggered through __getitem__ __iter__ = _ProxyLookup(iter) __next__ = _ProxyLookup(next) __reversed__ = _ProxyLookup(reversed) __contains__ = _ProxyLookup(operator.contains) __add__ = _ProxyLookup(operator.add) __sub__ = _ProxyLookup(operator.sub) __mul__ = _ProxyLookup(operator.mul) __matmul__ = _ProxyLookup(operator.matmul) __truediv__ = _ProxyLookup(operator.truediv) __floordiv__ = _ProxyLookup(operator.floordiv) __mod__ = _ProxyLookup(operator.mod) __divmod__ = _ProxyLookup(divmod) __pow__ = _ProxyLookup(pow) __lshift__ = _ProxyLookup(operator.lshift) __rshift__ = _ProxyLookup(operator.rshift) __and__ = _ProxyLookup(operator.and_) __xor__ = _ProxyLookup(operator.xor) __or__ = _ProxyLookup(operator.or_) __radd__ = _ProxyLookup(_l_to_r_op(operator.add)) __rsub__ = _ProxyLookup(_l_to_r_op(operator.sub)) __rmul__ = _ProxyLookup(_l_to_r_op(operator.mul)) __rmatmul__ = _ProxyLookup(_l_to_r_op(operator.matmul)) __rtruediv__ = _ProxyLookup(_l_to_r_op(operator.truediv)) __rfloordiv__ = _ProxyLookup(_l_to_r_op(operator.floordiv)) __rmod__ = _ProxyLookup(_l_to_r_op(operator.mod)) __rdivmod__ = _ProxyLookup(_l_to_r_op(divmod)) __rpow__ = _ProxyLookup(_l_to_r_op(pow)) __rlshift__ = _ProxyLookup(_l_to_r_op(operator.lshift)) __rrshift__ = _ProxyLookup(_l_to_r_op(operator.rshift)) __rand__ = _ProxyLookup(_l_to_r_op(operator.and_)) __rxor__ = _ProxyLookup(_l_to_r_op(operator.xor)) __ror__ = _ProxyLookup(_l_to_r_op(operator.or_)) __iadd__ = _ProxyIOp(operator.iadd) __isub__ = _ProxyIOp(operator.isub) __imul__ = _ProxyIOp(operator.imul) __imatmul__ = _ProxyIOp(operator.imatmul) __itruediv__ = _ProxyIOp(operator.itruediv) __ifloordiv__ = _ProxyIOp(operator.ifloordiv) __imod__ = _ProxyIOp(operator.imod) __ipow__ = _ProxyIOp(operator.ipow) __ilshift__ = _ProxyIOp(operator.ilshift) __irshift__ = _ProxyIOp(operator.irshift) __iand__ = _ProxyIOp(operator.iand) __ixor__ = _ProxyIOp(operator.ixor) __ior__ = _ProxyIOp(operator.ior) __neg__ = _ProxyLookup(operator.neg) __pos__ = _ProxyLookup(operator.pos) __abs__ = _ProxyLookup(abs) __invert__ = _ProxyLookup(operator.invert) __complex__ = _ProxyLookup(complex) __int__ = _ProxyLookup(int) __float__ = _ProxyLookup(float) __index__ = _ProxyLookup(operator.index) __round__ = _ProxyLookup(round) __trunc__ = _ProxyLookup(math.trunc) __floor__ = _ProxyLookup(math.floor) __ceil__ = _ProxyLookup(math.ceil) __enter__ = _ProxyLookup() __exit__ = _ProxyLookup() __await__ = _ProxyLookup() __aiter__ = _ProxyLookup() __anext__ = _ProxyLookup() __aenter__ = _ProxyLookup() __aexit__ = _ProxyLookup() __copy__ = _ProxyLookup(copy.copy) __deepcopy__ = _ProxyLookup(copy.deepcopy) # __getnewargs_ex__ (pickle through proxy not supported) # __getnewargs__ (pickle) # __getstate__ (pickle) # __setstate__ (pickle) # __reduce__ (pickle) # __reduce_ex__ (pickle)
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