app/django/template/context.py
author Pawel Solyga <Pawel.Solyga@gmail.com>
Tue, 27 Jan 2009 21:56:32 +0000
changeset 1015 b9d51be5104a
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
Add profiling support to Melange. By assigning profile_main_as_logs or profile_main_as_html to main variable you can turn on profiling. profile_main_as_logs will log profile data to App Engine console logs, profile_main_as_html will show profile data as html at the bottom of the page. If you want to profile app on deployed app just set the profiling function and deploy it. Patch by: Pawel Solyga Reviewed by: to-be-reviewed

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))