# Django 1.8.18.dev20170123152445 documentation

# Source code for django.core.urlresolvers

    """
    This module converts requested URLs to callback view functions.

    RegexURLResolver is the main class here. Its resolve() method takes a URL (as
    a string) and returns a ResolverMatch object which provides access to all
    attributes of the resolved URL match.
    """
    from __future__ import unicode_literals

    import functools
    import re
    import warnings
    from importlib import import_module
    from threading import local

    from django.core.exceptions import ImproperlyConfigured, ViewDoesNotExist
    from django.http import Http404
    from django.utils import lru_cache, six
    from django.utils.datastructures import MultiValueDict
    from django.utils.deprecation import RemovedInDjango110Warning
    from django.utils.encoding import force_str, force_text, iri_to_uri
    from django.utils.functional import lazy
    from django.utils.http import RFC3986_SUBDELIMS, urlquote
    from django.utils.module_loading import module_has_submodule
    from django.utils.regex_helper import normalize
    from django.utils.translation import get_language

    # SCRIPT_NAME prefixes for each thread are stored here. If there's no entry for
    # the current thread (which is the only one we ever access), it is assumed to
    # be empty.
    _prefixes = local()

    # Overridden URLconfs for each thread are stored here.
    _urlconfs = local()

    class ResolverMatch(object):
        def __init__(self, func, args, kwargs, url_name=None, app_name=None, namespaces=None):
            self.func = func
            self.args = args
            self.kwargs = kwargs
            self.url_name = url_name
            self.app_name = app_name

            if namespaces:
                self.namespaces = [x for x in namespaces if x]
            else:
                self.namespaces = []
            self.namespace = ':'.join(self.namespaces)

            if not hasattr(func, '__name__'):
                # A class-based view
                self._func_path = '.'.join([func.__class__.__module__, func.__class__.__name__])
            else:
                # A function-based view
                self._func_path = '.'.join([func.__module__, func.__name__])

            view_path = url_name or self._func_path
            self.view_name = ':'.join(self.namespaces + [view_path])

        def __getitem__(self, index):
            return (self.func, self.args, self.kwargs)[index]

        def __repr__(self):
            return "ResolverMatch(func=%s, args=%s, kwargs=%s, url_name=%s, app_name=%s, namespaces=%s)" % (
                self._func_path, self.args, self.kwargs, self.url_name, self.app_name, self.namespaces)

    class Resolver404(Http404):
        pass

    class NoReverseMatch(Exception):
        pass

    @lru_cache.lru_cache(maxsize=None)
    def get_callable(lookup_view, can_fail=False):
        """
        Return a callable corresponding to lookup_view. This function is used
        by both resolve() and reverse(), so can_fail allows the caller to choose
        between returning the input as is and raising an exception when the input
        string can't be interpreted as an import path.

        If lookup_view is already a callable, return it.
        If lookup_view is a string import path that can be resolved to a callable,
          import that callable and return it.
        If lookup_view is some other kind of string and can_fail is True, the string
          is returned as is. If can_fail is False, an exception is raised (either
          ImportError or ViewDoesNotExist).
        """
        if callable(lookup_view):
            return lookup_view

        mod_name, func_name = get_mod_func(lookup_view)
        if not func_name:  # No '.' in lookup_view
            if can_fail:
                return lookup_view
            else:
                raise ImportError(
                    "Could not import '%s'. The path must be fully qualified." %
                    lookup_view)

        try:
            mod = import_module(mod_name)
        except ImportError:
            if can_fail:
                return lookup_view
            else:
                parentmod, submod = get_mod_func(mod_name)
                if submod and not module_has_submodule(import_module(parentmod), submod):
                    raise ViewDoesNotExist(
                        "Could not import '%s'. Parent module %s does not exist." %
                        (lookup_view, mod_name))
                else:
                    raise
        else:
            try:
                view_func = getattr(mod, func_name)
            except AttributeError:
                if can_fail:
                    return lookup_view
                else:
                    raise ViewDoesNotExist(
                        "Could not import '%s'. View does not exist in module %s." %
                        (lookup_view, mod_name))
            else:
                if not callable(view_func):
                    # For backwards compatibility this is raised regardless of can_fail
                    raise ViewDoesNotExist(
                        "Could not import '%s.%s'. View is not callable." %
                        (mod_name, func_name))

                return view_func

    @lru_cache.lru_cache(maxsize=None)
    def get_resolver(urlconf):
        if urlconf is None:
            from django.conf import settings
            urlconf = settings.ROOT_URLCONF
        return RegexURLResolver(r'^/', urlconf)

    @lru_cache.lru_cache(maxsize=None)
    def get_ns_resolver(ns_pattern, resolver):
        # Build a namespaced resolver for the given parent urlconf pattern.
        # This makes it possible to have captured parameters in the parent
        # urlconf pattern.
        ns_resolver = RegexURLResolver(ns_pattern, resolver.url_patterns)
        return RegexURLResolver(r'^/', [ns_resolver])

    def get_mod_func(callback):
        # Converts 'django.views.news.stories.story_detail' to
        # ['django.views.news.stories', 'story_detail']
        try:
            dot = callback.rindex('.')
        except ValueError:
            return callback, ''
        return callback[:dot], callback[dot + 1:]

    class LocaleRegexProvider(object):
        """
        A mixin to provide a default regex property which can vary by active
        language.

        """
        def __init__(self, regex):
            # regex is either a string representing a regular expression, or a
            # translatable string (using ugettext_lazy) representing a regular
            # expression.
            self._regex = regex
            self._regex_dict = {}

        @property
        def regex(self):
            """
            Returns a compiled regular expression, depending upon the activated
            language-code.
            """
            language_code = get_language()
            if language_code not in self._regex_dict:
                if isinstance(self._regex, six.string_types):
                    regex = self._regex
                else:
                    regex = force_text(self._regex)
                try:
                    compiled_regex = re.compile(regex, re.UNICODE)
                except re.error as e:
                    raise ImproperlyConfigured(
                        '"%s" is not a valid regular expression: %s' %
                        (regex, six.text_type(e)))

                self._regex_dict[language_code] = compiled_regex
            return self._regex_dict[language_code]

    class RegexURLPattern(LocaleRegexProvider):
        def __init__(self, regex, callback, default_args=None, name=None):
            LocaleRegexProvider.__init__(self, regex)
            # callback is either a string like 'foo.views.news.stories.story_detail'
            # which represents the path to a module and a view function name, or a
            # callable object (view).
            if callable(callback):
                self._callback = callback
            else:
                self._callback = None
                self._callback_str = callback
            self.default_args = default_args or {}
            self.name = name

        def __repr__(self):
            return force_str('<%s %s %s>' % (self.__class__.__name__, self.name, self.regex.pattern))

        def add_prefix(self, prefix):
            """
            Adds the prefix string to a string-based callback.
            """
            if not prefix or not hasattr(self, '_callback_str'):
                return
            self._callback_str = prefix + '.' + self._callback_str

        def resolve(self, path):
            match = self.regex.search(path)
            if match:
                # If there are any named groups, use those as kwargs, ignoring
                # non-named groups. Otherwise, pass all non-named arguments as
                # positional arguments.
                kwargs = match.groupdict()
                if kwargs:
                    args = ()
                else:
                    args = match.groups()
                # In both cases, pass any extra_kwargs as **kwargs.
                kwargs.update(self.default_args)

                return ResolverMatch(self.callback, args, kwargs, self.name)

        @property
        def callback(self):
            if self._callback is not None:
                return self._callback

            self._callback = get_callable(self._callback_str)
            return self._callback

    class RegexURLResolver(LocaleRegexProvider):
        def __init__(self, regex, urlconf_name, default_kwargs=None, app_name=None, namespace=None):
            LocaleRegexProvider.__init__(self, regex)
            # urlconf_name is a string representing the module containing URLconfs.
            self.urlconf_name = urlconf_name
            if not isinstance(urlconf_name, six.string_types):
                self._urlconf_module = self.urlconf_name
            self.callback = None
            self.default_kwargs = default_kwargs or {}
            self.namespace = namespace
            self.app_name = app_name
            self._reverse_dict = {}
            self._namespace_dict = {}
            self._app_dict = {}
            # set of dotted paths to all functions and classes that are used in
            # urlpatterns
            self._callback_strs = set()
            self._populated = False

        def __repr__(self):
            if isinstance(self.urlconf_name, list) and len(self.urlconf_name):
                # Don't bother to output the whole list, it can be huge
                urlconf_repr = '<%s list>' % self.urlconf_name[0].__class__.__name__
            else:
                urlconf_repr = repr(self.urlconf_name)
            return str('<%s %s (%s:%s) %s>') % (
                self.__class__.__name__, urlconf_repr, self.app_name,
                self.namespace, self.regex.pattern)

        def _populate(self):
            lookups = MultiValueDict()
            namespaces = {}
            apps = {}
            language_code = get_language()
            for pattern in reversed(self.url_patterns):
                if hasattr(pattern, '_callback_str'):
                    self._callback_strs.add(pattern._callback_str)
                elif hasattr(pattern, '_callback'):
                    callback = pattern._callback
                    if isinstance(callback, functools.partial):
                        callback = callback.func

                    if not hasattr(callback, '__name__'):
                        lookup_str = callback.__module__ + "." + callback.__class__.__name__
                    else:
                        lookup_str = callback.__module__ + "." + callback.__name__
                    self._callback_strs.add(lookup_str)
                p_pattern = pattern.regex.pattern
                if p_pattern.startswith('^'):
                    p_pattern = p_pattern[1:]
                if isinstance(pattern, RegexURLResolver):
                    if pattern.namespace:
                        namespaces[pattern.namespace] = (p_pattern, pattern)
                        if pattern.app_name:
                            apps.setdefault(pattern.app_name, []).append(pattern.namespace)
                    else:
                        parent_pat = pattern.regex.pattern
                        for name in pattern.reverse_dict:
                            for matches, pat, defaults in pattern.reverse_dict.getlist(name):
                                new_matches = normalize(parent_pat + pat)
                                lookups.appendlist(
                                    name,
                                    (
                                        new_matches,
                                        p_pattern + pat,
                                        dict(defaults, **pattern.default_kwargs),
                                    )
                                )
                        for namespace, (prefix, sub_pattern) in pattern.namespace_dict.items():
                            namespaces[namespace] = (p_pattern + prefix, sub_pattern)
                        for app_name, namespace_list in pattern.app_dict.items():
                            apps.setdefault(app_name, []).extend(namespace_list)
                        self._callback_strs.update(pattern._callback_strs)
                else:
                    bits = normalize(p_pattern)
                    lookups.appendlist(pattern.callback, (bits, p_pattern, pattern.default_args))
                    if pattern.name is not None:
                        lookups.appendlist(pattern.name, (bits, p_pattern, pattern.default_args))
            self._reverse_dict[language_code] = lookups
            self._namespace_dict[language_code] = namespaces
            self._app_dict[language_code] = apps
            self._populated = True

        @property
        def reverse_dict(self):
            language_code = get_language()
            if language_code not in self._reverse_dict:
                self._populate()
            return self._reverse_dict[language_code]

        @property
        def namespace_dict(self):
            language_code = get_language()
            if language_code not in self._namespace_dict:
                self._populate()
            return self._namespace_dict[language_code]

        @property
        def app_dict(self):
            language_code = get_language()
            if language_code not in self._app_dict:
                self._populate()
            return self._app_dict[language_code]

        def _is_callback(self, name):
            if not self._populated:
                self._populate()
            return name in self._callback_strs

        def resolve(self, path):
            path = force_text(path)  # path may be a reverse_lazy object
            tried = []
            match = self.regex.search(path)
            if match:
                new_path = path[match.end():]
                for pattern in self.url_patterns:
                    try:
                        sub_match = pattern.resolve(new_path)
                    except Resolver404 as e:
                        sub_tried = e.args[0].get('tried')
                        if sub_tried is not None:
                            tried.extend([pattern] + t for t in sub_tried)
                        else:
                            tried.append([pattern])
                    else:
                        if sub_match:
                            sub_match_dict = dict(match.groupdict(), **self.default_kwargs)
                            sub_match_dict.update(sub_match.kwargs)
                            return ResolverMatch(
                                sub_match.func,
                                sub_match.args,
                                sub_match_dict,
                                sub_match.url_name,
                                self.app_name or sub_match.app_name,
                                [self.namespace] + sub_match.namespaces
                            )
                        tried.append([pattern])
                raise Resolver404({'tried': tried, 'path': new_path})
            raise Resolver404({'path': path})

        @property
        def urlconf_module(self):
            try:
                return self._urlconf_module
            except AttributeError:
                self._urlconf_module = import_module(self.urlconf_name)
                return self._urlconf_module

        @property
        def url_patterns(self):
            # urlconf_module might be a valid set of patterns, so we default to it
            patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
            try:
                iter(patterns)
            except TypeError:
                msg = (
                    "The included urlconf '{name}' does not appear to have any "
                    "patterns in it. If you see valid patterns in the file then "
                    "the issue is probably caused by a circular import."
                )
                raise ImproperlyConfigured(msg.format(name=self.urlconf_name))
            return patterns

        def resolve_error_handler(self, view_type):
            callback = getattr(self.urlconf_module, 'handler%s' % view_type, None)
            if not callback:
                # No handler specified in file; use default
                # Lazy import, since django.urls imports this file
                from django.conf import urls
                callback = getattr(urls, 'handler%s' % view_type)
            return get_callable(callback), {}

        def reverse(self, lookup_view, *args, **kwargs):
            return self._reverse_with_prefix(lookup_view, '', *args, **kwargs)

        def _reverse_with_prefix(self, lookup_view, _prefix, *args, **kwargs):
            if args and kwargs:
                raise ValueError("Don't mix *args and **kwargs in call to reverse()!")
            text_args = [force_text(v) for v in args]
            text_kwargs = {k: force_text(v) for (k, v) in kwargs.items()}

            if not self._populated:
                self._populate()

            original_lookup = lookup_view
            try:
                if self._is_callback(lookup_view):
                    lookup_view = get_callable(lookup_view, True)
            except (ImportError, AttributeError) as e:
                raise NoReverseMatch("Error importing '%s': %s." % (lookup_view, e))
            else:
                if not callable(original_lookup) and callable(lookup_view):
                    warnings.warn(
                        'Reversing by dotted path is deprecated (%s).' % original_lookup,
                        RemovedInDjango110Warning, stacklevel=3
                    )
            possibilities = self.reverse_dict.getlist(lookup_view)

            prefix_norm, prefix_args = normalize(urlquote(_prefix))[0]
            for possibility, pattern, defaults in possibilities:
                for result, params in possibility:
                    if args:
                        if len(args) != len(params) + len(prefix_args):
                            continue
                        candidate_subs = dict(zip(prefix_args + params, text_args))
                    else:
                        if (set(kwargs.keys()) | set(defaults.keys()) != set(params) |
                                set(defaults.keys()) | set(prefix_args)):
                            continue
                        matches = True
                        for k, v in defaults.items():
                            if kwargs.get(k, v) != v:
                                matches = False
                                break
                        if not matches:
                            continue
                        candidate_subs = text_kwargs
                    # WSGI provides decoded URLs, without %xx escapes, and the URL
                    # resolver operates on such URLs. First substitute arguments
                    # without quoting to build a decoded URL and look for a match.
                    # Then, if we have a match, redo the substitution with quoted
                    # arguments in order to return a properly encoded URL.
                    candidate_pat = prefix_norm.replace('%', '%%') + result
                    if re.search('^%s%s' % (prefix_norm, pattern), candidate_pat % candidate_subs, re.UNICODE):
                        # safe characters from `pchar` definition of RFC 3986
                        candidate_subs = dict((k, urlquote(v, safe=RFC3986_SUBDELIMS + str('/~:@')))
                                              for (k, v) in candidate_subs.items())
                        url = candidate_pat % candidate_subs
                        # Don't allow construction of scheme relative urls.
                        if url.startswith('//'):
                            url = '/%%2F%s' % url[2:]
                        return url
            # lookup_view can be URL label, or dotted path, or callable, Any of
            # these can be passed in at the top, but callables are not friendly in
            # error messages.
            m = getattr(lookup_view, '__module__', None)
            n = getattr(lookup_view, '__name__', None)
            if m is not None and n is not None:
                lookup_view_s = "%s.%s" % (m, n)
            else:
                lookup_view_s = lookup_view

            patterns = [pattern for (possibility, pattern, defaults) in possibilities]
            raise NoReverseMatch("Reverse for '%s' with arguments '%s' and keyword "
                    "arguments '%s' not found. %d pattern(s) tried: %s" %
                                 (lookup_view_s, args, kwargs, len(patterns), patterns))

    class LocaleRegexURLResolver(RegexURLResolver):
        """
        A URL resolver that always matches the active language code as URL prefix.

        Rather than taking a regex argument, we just override the ``regex``
        function to always return the active language-code as regex.
        """
        def __init__(self, urlconf_name, default_kwargs=None, app_name=None, namespace=None):
            super(LocaleRegexURLResolver, self).__init__(
                None, urlconf_name, default_kwargs, app_name, namespace)

        @property
        def regex(self):
            language_code = get_language()
            if language_code not in self._regex_dict:
                regex_compiled = re.compile('^%s/' % language_code, re.UNICODE)
                self._regex_dict[language_code] = regex_compiled
            return self._regex_dict[language_code]

    def resolve(path, urlconf=None):
        if urlconf is None:
            urlconf = get_urlconf()
        return get_resolver(urlconf).resolve(path)

    def reverse(viewname, urlconf=None, args=None, kwargs=None, prefix=None, current_app=None):
        if urlconf is None:
            urlconf = get_urlconf()
        resolver = get_resolver(urlconf)
        args = args or []
        kwargs = kwargs or {}

        if prefix is None:
            prefix = get_script_prefix()

        if not isinstance(viewname, six.string_types):
            view = viewname
        else:
            parts = viewname.split(':')
            parts.reverse()
            view = parts[0]
            path = parts[1:]

            resolved_path = []
            ns_pattern = ''
            while path:
                ns = path.pop()

                # Lookup the name to see if it could be an app identifier
                try:
                    app_list = resolver.app_dict[ns]
                    # Yes! Path part matches an app in the current Resolver
                    if current_app and current_app in app_list:
                        # If we are reversing for a particular app,
                        # use that namespace
                        ns = current_app
                    elif ns not in app_list:
                        # The name isn't shared by one of the instances
                        # (i.e., the default) so just pick the first instance
                        # as the default.
                        ns = app_list[0]
                except KeyError:
                    pass

                try:
                    extra, resolver = resolver.namespace_dict[ns]
                    resolved_path.append(ns)
                    ns_pattern = ns_pattern + extra
                except KeyError as key:
                    if resolved_path:
                        raise NoReverseMatch(
                            "%s is not a registered namespace inside '%s'" %
                            (key, ':'.join(resolved_path)))
                    else:
                        raise NoReverseMatch("%s is not a registered namespace" %
                                             key)
            if ns_pattern:
                resolver = get_ns_resolver(ns_pattern, resolver)

        return force_text(iri_to_uri(resolver._reverse_with_prefix(view, prefix, *args, **kwargs)))

    reverse_lazy = lazy(reverse, six.text_type)

    def clear_url_caches():
        get_callable.cache_clear()
        get_resolver.cache_clear()
        get_ns_resolver.cache_clear()

    def set_script_prefix(prefix):
        """
        Sets the script prefix for the current thread.
        """
        if not prefix.endswith('/'):
            prefix += '/'
        _prefixes.value = prefix

    def get_script_prefix():
        """
        Returns the currently active script prefix. Useful for client code that
        wishes to construct their own URLs manually (although accessing the request
        instance is normally going to be a lot cleaner).
        """
        return getattr(_prefixes, "value", '/')

    def clear_script_prefix():
        """
        Unsets the script prefix for the current thread.
        """
        try:
            del _prefixes.value
        except AttributeError:
            pass

    def set_urlconf(urlconf_name):
        """
        Sets the URLconf for the current thread (overriding the default one in
        settings). Set to None to revert back to the default.
        """
        if urlconf_name:
            _urlconfs.value = urlconf_name
        else:
            if hasattr(_urlconfs, "value"):
                del _urlconfs.value

    def get_urlconf(default=None):
        """
        Returns the root URLconf to use for the current thread if it has been
        changed from the default one.
        """
        return getattr(_urlconfs, "value", default)

    def is_valid_path(path, urlconf=None):
        """
        Returns True if the given path resolves against the default URL resolver,
        False otherwise.

        This is a convenience method to make working with "is this a match?" cases
        easier, avoiding unnecessarily indented try...except blocks.
        """
        try:
            resolve(path, urlconf)
            return True
        except Resolver404:
            return False