+
−from django.conf import settings
+
−from django.core.exceptions import ImproperlyConfigured
+
−
+
−_standard_context_processors = None
+
−
+
−class ContextPopException(Exception):
+
−    "pop() has been called more times than push()"
+
−    pass
+
−
+
−class Context(object):
+
−    "A stack container for variable context"
+
−    def __init__(self, dict_=None, autoescape=True):
+
−        dict_ = dict_ or {}
+
−        self.dicts = [dict_]
+
−        self.autoescape = autoescape
+
−
+
−    def __repr__(self):
+
−        return repr(self.dicts)
+
−
+
−    def __iter__(self):
+
−        for d in self.dicts:
+
−            yield d
+
−
+
−    def push(self):
+
−        d = {}
+
−        self.dicts = [d] + self.dicts
+
−        return d
+
−
+
−    def pop(self):
+
−        if len(self.dicts) == 1:
+
−            raise ContextPopException
+
−        return self.dicts.pop(0)
+
−
+
−    def __setitem__(self, key, value):
+
−        "Set a variable in the current context"
+
−        self.dicts[0][key] = value
+
−
+
−    def __getitem__(self, key):
+
−        "Get a variable's value, starting at the current context and going upward"
+
−        for d in self.dicts:
+
−            if key in d:
+
−                return d[key]
+
−        raise KeyError(key)
+
−
+
−    def __delitem__(self, key):
+
−        "Delete a variable from the current context"
+
−        del self.dicts[0][key]
+
−
+
−    def has_key(self, key):
+
−        for d in self.dicts:
+
−            if key in d:
+
−                return True
+
−        return False
+
−
+
−    __contains__ = has_key
+
−
+
−    def get(self, key, otherwise=None):
+
−        for d in self.dicts:
+
−            if key in d:
+
−                return d[key]
+
−        return otherwise
+
−
+
−    def update(self, other_dict):
+
−        "Like dict.update(). Pushes an entire dictionary's keys and values onto the context."
+
−        if not hasattr(other_dict, '__getitem__'): 
+
−            raise TypeError('other_dict must be a mapping (dictionary-like) object.')
+
−        self.dicts = [other_dict] + self.dicts
+
−        return other_dict
+
−
+
−# This is a function rather than module-level procedural code because we only
+
−# want it to execute if somebody uses RequestContext.
+
−def get_standard_processors():
+
−    global _standard_context_processors
+
−    if _standard_context_processors is None:
+
−        processors = []
+
−        for path in settings.TEMPLATE_CONTEXT_PROCESSORS:
+
−            i = path.rfind('.')
+
−            module, attr = path[:i], path[i+1:]
+
−            try:
+
−                mod = __import__(module, {}, {}, [attr])
+
−            except ImportError, e:
+
−                raise ImproperlyConfigured('Error importing request processor module %s: "%s"' % (module, e))
+
−            try:
+
−                func = getattr(mod, attr)
+
−            except AttributeError:
+
−                raise ImproperlyConfigured('Module "%s" does not define a "%s" callable request processor' % (module, attr))
+
−            processors.append(func)
+
−        _standard_context_processors = tuple(processors)
+
−    return _standard_context_processors
+
−
+
−class RequestContext(Context):
+
−    """
+
−    This subclass of template.Context automatically populates itself using
+
−    the processors defined in TEMPLATE_CONTEXT_PROCESSORS.
+
−    Additional processors can be specified as a list of callables
+
−    using the "processors" keyword argument.
+
−    """
+
−    def __init__(self, request, dict=None, processors=None):
+
−        Context.__init__(self, dict)
+
−        if processors is None:
+
−            processors = ()
+
−        else:
+
−            processors = tuple(processors)
+
−        for processor in get_standard_processors() + processors:
+
−            self.update(processor(request))