class EmptyChangeset(BaseChangeset):

    """

    An dummy empty changeset. It's possible to pass hash when creating

    an EmptyChangeset

    """

    def __init__(self, cs='0' * 40):

        self._empty_cs = cs

        self.revision = -1

        self.message = ''

        self.author = ''

        self.date = ''

    @LazyProperty

    def raw_id(self):

        """

        Returns raw string identifying this changeset, useful for web

        representation.

        """

        return self._empty_cs

    @LazyProperty

    def short_id(self):

        return self.raw_id[:12]

    def get_file_changeset(self, path):

        return self

    def get_file_content(self, path):

        return u''

    def get_file_size(self, path):

        return 0

def repo2db_mapper(initial_repo_list, remove_obsolete=False):

    """

    maps all found repositories into db

    """

    sa = meta.Session()

    rm = RepoModel(sa)

    user = sa.query(User).filter(User.admin == True).first()

    for name, repo in initial_repo_list.items():

        if not rm.get(name, cache=False):

            log.info('repository %s not found creating default', name)

            form_data = {

                         'repo_name':name,

                         'description':repo.description if repo.description != 'unknown' else \

                                        'auto description for %s' % name,

                         'private':False

                         }

            rm.create(form_data, user, just_db=True)

    if remove_obsolete:

        #remove from database those repositories that are not in the filesystem

        for repo in sa.query(Repository).all():

            if repo.repo_name not in initial_repo_list.keys():

                sa.delete(repo)

                sa.commit()

    meta.Session.remove()

class OrderedDict(dict, DictMixin):

    def __init__(self, *args, **kwds):

        if len(args) > 1:

            raise TypeError('expected at most 1 arguments, got %d' % len(args))

        try:

            self.__end

        except AttributeError:

            self.clear()

        self.update(*args, **kwds)

    def clear(self):

        self.__end = end = []

        end += [None, end, end]         # sentinel node for doubly linked list

        self.__map = {}                 # key --> [key, prev, next]

        dict.clear(self)

    def __setitem__(self, key, value):

        if key not in self:

            end = self.__end

            curr = end[1]

            curr[2] = end[1] = self.__map[key] = [key, curr, end]

        dict.__setitem__(self, key, value)

    def __delitem__(self, key):

        dict.__delitem__(self, key)

        key, prev, next = self.__map.pop(key)

        prev[2] = next

        next[1] = prev