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420 lines
14 KiB
420 lines
14 KiB
# -*- coding: utf-8 -*-
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"""
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werkzeug.local
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~~~~~~~~~~~~~~
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This module implements context-local objects.
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:copyright: (c) 2014 by the Werkzeug Team, see AUTHORS for more details.
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:license: BSD, see LICENSE for more details.
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"""
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import copy
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from functools import update_wrapper
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from werkzeug.wsgi import ClosingIterator
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from werkzeug._compat import PY2, implements_bool
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# since each thread has its own greenlet we can just use those as identifiers
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# for the context. If greenlets are not available we fall back to the
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# current thread ident depending on where it is.
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try:
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from greenlet import getcurrent as get_ident
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except ImportError:
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try:
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from thread import get_ident
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except ImportError:
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from _thread import get_ident
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def release_local(local):
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"""Releases the contents of the local for the current context.
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This makes it possible to use locals without a manager.
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Example::
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>>> loc = Local()
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>>> loc.foo = 42
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>>> release_local(loc)
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>>> hasattr(loc, 'foo')
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False
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With this function one can release :class:`Local` objects as well
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as :class:`LocalStack` objects. However it is not possible to
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release data held by proxies that way, one always has to retain
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a reference to the underlying local object in order to be able
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to release it.
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.. versionadded:: 0.6.1
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"""
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local.__release_local__()
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class Local(object):
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__slots__ = ('__storage__', '__ident_func__')
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def __init__(self):
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object.__setattr__(self, '__storage__', {})
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object.__setattr__(self, '__ident_func__', get_ident)
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def __iter__(self):
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return iter(self.__storage__.items())
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def __call__(self, proxy):
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"""Create a proxy for a name."""
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return LocalProxy(self, proxy)
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def __release_local__(self):
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self.__storage__.pop(self.__ident_func__(), None)
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def __getattr__(self, name):
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try:
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return self.__storage__[self.__ident_func__()][name]
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except KeyError:
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raise AttributeError(name)
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def __setattr__(self, name, value):
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ident = self.__ident_func__()
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storage = self.__storage__
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try:
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storage[ident][name] = value
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except KeyError:
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storage[ident] = {name: value}
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def __delattr__(self, name):
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try:
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del self.__storage__[self.__ident_func__()][name]
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except KeyError:
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raise AttributeError(name)
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class LocalStack(object):
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"""This class works similar to a :class:`Local` but keeps a stack
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of objects instead. This is best explained with an example::
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>>> ls = LocalStack()
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>>> ls.push(42)
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>>> ls.top
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42
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>>> ls.push(23)
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>>> ls.top
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23
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>>> ls.pop()
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23
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>>> ls.top
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42
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They can be force released by using a :class:`LocalManager` or with
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the :func:`release_local` function but the correct way is to pop the
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item from the stack after using. When the stack is empty it will
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no longer be bound to the current context (and as such released).
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By calling the stack without arguments it returns a proxy that resolves to
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the topmost item on the stack.
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.. versionadded:: 0.6.1
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"""
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def __init__(self):
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self._local = Local()
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def __release_local__(self):
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self._local.__release_local__()
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def _get__ident_func__(self):
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return self._local.__ident_func__
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def _set__ident_func__(self, value):
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object.__setattr__(self._local, '__ident_func__', value)
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__ident_func__ = property(_get__ident_func__, _set__ident_func__)
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del _get__ident_func__, _set__ident_func__
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def __call__(self):
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def _lookup():
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rv = self.top
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if rv is None:
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raise RuntimeError('object unbound')
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return rv
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return LocalProxy(_lookup)
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def push(self, obj):
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"""Pushes a new item to the stack"""
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rv = getattr(self._local, 'stack', None)
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if rv is None:
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self._local.stack = rv = []
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rv.append(obj)
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return rv
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def pop(self):
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"""Removes the topmost item from the stack, will return the
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old value or `None` if the stack was already empty.
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"""
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stack = getattr(self._local, 'stack', None)
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if stack is None:
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return None
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elif len(stack) == 1:
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release_local(self._local)
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return stack[-1]
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else:
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return stack.pop()
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@property
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def top(self):
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"""The topmost item on the stack. If the stack is empty,
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`None` is returned.
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"""
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try:
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return self._local.stack[-1]
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except (AttributeError, IndexError):
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return None
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class LocalManager(object):
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"""Local objects cannot manage themselves. For that you need a local
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manager. You can pass a local manager multiple locals or add them later
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by appending them to `manager.locals`. Every time the manager cleans up,
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it will clean up all the data left in the locals for this context.
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The `ident_func` parameter can be added to override the default ident
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function for the wrapped locals.
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.. versionchanged:: 0.6.1
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Instead of a manager the :func:`release_local` function can be used
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as well.
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.. versionchanged:: 0.7
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`ident_func` was added.
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"""
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def __init__(self, locals=None, ident_func=None):
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if locals is None:
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self.locals = []
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elif isinstance(locals, Local):
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self.locals = [locals]
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else:
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self.locals = list(locals)
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if ident_func is not None:
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self.ident_func = ident_func
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for local in self.locals:
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object.__setattr__(local, '__ident_func__', ident_func)
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else:
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self.ident_func = get_ident
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def get_ident(self):
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"""Return the context identifier the local objects use internally for
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this context. You cannot override this method to change the behavior
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but use it to link other context local objects (such as SQLAlchemy's
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scoped sessions) to the Werkzeug locals.
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.. versionchanged:: 0.7
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You can pass a different ident function to the local manager that
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will then be propagated to all the locals passed to the
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constructor.
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"""
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return self.ident_func()
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def cleanup(self):
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"""Manually clean up the data in the locals for this context. Call
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this at the end of the request or use `make_middleware()`.
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"""
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for local in self.locals:
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release_local(local)
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def make_middleware(self, app):
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"""Wrap a WSGI application so that cleaning up happens after
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request end.
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"""
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def application(environ, start_response):
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return ClosingIterator(app(environ, start_response), self.cleanup)
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return application
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def middleware(self, func):
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"""Like `make_middleware` but for decorating functions.
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Example usage::
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@manager.middleware
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def application(environ, start_response):
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...
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The difference to `make_middleware` is that the function passed
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will have all the arguments copied from the inner application
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(name, docstring, module).
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"""
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return update_wrapper(self.make_middleware(func), func)
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def __repr__(self):
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return '<%s storages: %d>' % (
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self.__class__.__name__,
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len(self.locals)
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)
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@implements_bool
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class LocalProxy(object):
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"""Acts as a proxy for a werkzeug local. Forwards all operations to
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a proxied object. The only operations not supported for forwarding
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are right handed operands and any kind of assignment.
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Example usage::
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from werkzeug.local import Local
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l = Local()
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# these are proxies
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request = l('request')
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user = l('user')
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from werkzeug.local import LocalStack
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_response_local = LocalStack()
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# this is a proxy
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response = _response_local()
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Whenever something is bound to l.user / l.request the proxy objects
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will forward all operations. If no object is bound a :exc:`RuntimeError`
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will be raised.
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To create proxies to :class:`Local` or :class:`LocalStack` objects,
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call the object as shown above. If you want to have a proxy to an
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object looked up by a function, you can (as of Werkzeug 0.6.1) pass
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a function to the :class:`LocalProxy` constructor::
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session = LocalProxy(lambda: get_current_request().session)
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.. versionchanged:: 0.6.1
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The class can be instantiated with a callable as well now.
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"""
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__slots__ = ('__local', '__dict__', '__name__', '__wrapped__')
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def __init__(self, local, name=None):
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object.__setattr__(self, '_LocalProxy__local', local)
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object.__setattr__(self, '__name__', name)
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if callable(local) and not hasattr(local, '__release_local__'):
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# "local" is a callable that is not an instance of Local or
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# LocalManager: mark it as a wrapped function.
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object.__setattr__(self, '__wrapped__', local)
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def _get_current_object(self):
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"""Return the current object. This is useful if you want the real
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object behind the proxy at a time for performance reasons or because
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you want to pass the object into a different context.
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"""
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if not hasattr(self.__local, '__release_local__'):
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return self.__local()
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try:
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return getattr(self.__local, self.__name__)
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except AttributeError:
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raise RuntimeError('no object bound to %s' % self.__name__)
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@property
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def __dict__(self):
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try:
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return self._get_current_object().__dict__
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except RuntimeError:
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raise AttributeError('__dict__')
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def __repr__(self):
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try:
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obj = self._get_current_object()
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except RuntimeError:
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return '<%s unbound>' % self.__class__.__name__
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return repr(obj)
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def __bool__(self):
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try:
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return bool(self._get_current_object())
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except RuntimeError:
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return False
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def __unicode__(self):
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try:
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return unicode(self._get_current_object()) # noqa
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except RuntimeError:
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return repr(self)
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def __dir__(self):
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try:
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return dir(self._get_current_object())
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except RuntimeError:
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return []
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def __getattr__(self, name):
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if name == '__members__':
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return dir(self._get_current_object())
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return getattr(self._get_current_object(), name)
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def __setitem__(self, key, value):
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self._get_current_object()[key] = value
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def __delitem__(self, key):
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del self._get_current_object()[key]
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if PY2:
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__getslice__ = lambda x, i, j: x._get_current_object()[i:j]
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def __setslice__(self, i, j, seq):
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self._get_current_object()[i:j] = seq
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def __delslice__(self, i, j):
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del self._get_current_object()[i:j]
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__setattr__ = lambda x, n, v: setattr(x._get_current_object(), n, v)
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__delattr__ = lambda x, n: delattr(x._get_current_object(), n)
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__str__ = lambda x: str(x._get_current_object())
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__lt__ = lambda x, o: x._get_current_object() < o
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__le__ = lambda x, o: x._get_current_object() <= o
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__eq__ = lambda x, o: x._get_current_object() == o
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__ne__ = lambda x, o: x._get_current_object() != o
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__gt__ = lambda x, o: x._get_current_object() > o
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__ge__ = lambda x, o: x._get_current_object() >= o
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__cmp__ = lambda x, o: cmp(x._get_current_object(), o) # noqa
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__hash__ = lambda x: hash(x._get_current_object())
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__call__ = lambda x, *a, **kw: x._get_current_object()(*a, **kw)
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__len__ = lambda x: len(x._get_current_object())
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__getitem__ = lambda x, i: x._get_current_object()[i]
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__iter__ = lambda x: iter(x._get_current_object())
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__contains__ = lambda x, i: i in x._get_current_object()
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__add__ = lambda x, o: x._get_current_object() + o
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__sub__ = lambda x, o: x._get_current_object() - o
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__mul__ = lambda x, o: x._get_current_object() * o
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__floordiv__ = lambda x, o: x._get_current_object() // o
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__mod__ = lambda x, o: x._get_current_object() % o
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__divmod__ = lambda x, o: x._get_current_object().__divmod__(o)
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__pow__ = lambda x, o: x._get_current_object() ** o
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__lshift__ = lambda x, o: x._get_current_object() << o
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__rshift__ = lambda x, o: x._get_current_object() >> o
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__and__ = lambda x, o: x._get_current_object() & o
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__xor__ = lambda x, o: x._get_current_object() ^ o
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__or__ = lambda x, o: x._get_current_object() | o
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__div__ = lambda x, o: x._get_current_object().__div__(o)
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__truediv__ = lambda x, o: x._get_current_object().__truediv__(o)
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__neg__ = lambda x: -(x._get_current_object())
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__pos__ = lambda x: +(x._get_current_object())
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__abs__ = lambda x: abs(x._get_current_object())
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__invert__ = lambda x: ~(x._get_current_object())
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__complex__ = lambda x: complex(x._get_current_object())
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__int__ = lambda x: int(x._get_current_object())
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__long__ = lambda x: long(x._get_current_object()) # noqa
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__float__ = lambda x: float(x._get_current_object())
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__oct__ = lambda x: oct(x._get_current_object())
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__hex__ = lambda x: hex(x._get_current_object())
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__index__ = lambda x: x._get_current_object().__index__()
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__coerce__ = lambda x, o: x._get_current_object().__coerce__(x, o)
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__enter__ = lambda x: x._get_current_object().__enter__()
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__exit__ = lambda x, *a, **kw: x._get_current_object().__exit__(*a, **kw)
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__radd__ = lambda x, o: o + x._get_current_object()
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__rsub__ = lambda x, o: o - x._get_current_object()
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__rmul__ = lambda x, o: o * x._get_current_object()
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__rdiv__ = lambda x, o: o / x._get_current_object()
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if PY2:
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__rtruediv__ = lambda x, o: x._get_current_object().__rtruediv__(o)
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else:
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__rtruediv__ = __rdiv__
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__rfloordiv__ = lambda x, o: o // x._get_current_object()
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__rmod__ = lambda x, o: o % x._get_current_object()
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__rdivmod__ = lambda x, o: x._get_current_object().__rdivmod__(o)
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__copy__ = lambda x: copy.copy(x._get_current_object())
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__deepcopy__ = lambda x, memo: copy.deepcopy(x._get_current_object(), memo)
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