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