size += tip.get_file_size(f.path)

        except RepositoryError as e:

            pass

        return size

    def is_valid(self):

        """

        Validates repository.

        """

        raise NotImplementedError

    def is_empty(self):

        return self._empty

    #==========================================================================

    # CHANGESETS

    #==========================================================================

    def get_changeset(self, revision=None):

        """

        Returns instance of ``Changeset`` class. If ``revision`` is None, most

        recent changeset is returned.

        :raises ``EmptyRepositoryError``: if there are no revisions

        """

        raise NotImplementedError

    def __iter__(self):

        """

        Allows Repository objects to be iterated.

        *Requires* implementation of ``__getitem__`` method.

        """

        for revision in self.revisions:

            yield self.get_changeset(revision)

    def get_changesets(self, start=None, end=None, start_date=None,

                       end_date=None, branch_name=None, reverse=False, max_revisions=None):

        """

        Returns iterator of ``BaseChangeset`` objects from start to end,

        both inclusive.

        :param start: None or str

        :param end: None or str

        :param start_date:

        :param end_date:

        :param branch_name:

        """

        raise NotImplementedError

    def get_diff_changesets(self, org_rev, other_repo, other_rev):

        """

        Returns lists of changesets that can be merged from this repo @org_rev

        to other_repo @other_rev

        ... and the other way

        ... and the ancestors that would be used for merge

        :param org_rev: the revision we want our compare to be made

        :param other_repo: repo object, most likely the fork of org_repo. It has

            all changesets that we need to obtain

        :param other_rev: revision we want out compare to be made on other_repo

        """

        raise NotImplementedError

    def __getitem__(self, key):

        if isinstance(key, slice):

            return (self.get_changeset(rev) for rev in self.revisions[key])

        return self.get_changeset(key)

    def count(self):

        return len(self.revisions)

    def tag(self, name, user, revision=None, message=None, date=None, **opts):

        """

        Creates and returns a tag for the given ``revision``.

        :param name: name for new tag

        :param user: full username, i.e.: "Joe Doe <joe.doe@example.com>"

        :param revision: changeset id for which new tag would be created

        :param message: message of the tag's commit

        :param date: date of tag's commit

        :raises TagAlreadyExistError: if tag with same name already exists

        """

        raise NotImplementedError

    def remove_tag(self, name, user, message=None, date=None):

        """

        Removes tag with the given ``name``.

        :param name: name of the tag to be removed

        :param user: full username, i.e.: "Joe Doe <joe.doe@example.com>"

        :param message: message of the tag's removal commit

        :param date: date of tag's removal commit

            raise ChangesetDoesNotExistError(msg)

        except mercurial.error.RepoLookupError:

            msg = "Revision %s:%s does not exist for %s" % (ref_type, ref_name, self.name)

            raise ChangesetDoesNotExistError(msg)

        if revs:

            revision = revs.last()

        else:

            # TODO: just report 'not found'?

            revision = ref_name

        return self._get_revision(revision)

    def _get_archives(self, archive_name='tip'):

        allowed = self.baseui.configlist(b"web", b"allow_archive",

                                         untrusted=True)

        for name, ext in [(b'zip', '.zip'), (b'gz', '.tar.gz'), (b'bz2', '.tar.bz2')]:

            if name in allowed or self._repo.ui.configbool(b"web",

                                                           b"allow" + name,

                                                           untrusted=True):

                yield {"type": safe_str(name), "extension": ext, "node": archive_name}

    def _get_url(self, url):

        """

        Returns normalized url. If schema is not given, fall back to

        filesystem (``file:///``) schema.

        """

        if url != 'default' and '://' not in url:

            url = "file:" + urllib.request.pathname2url(url)

        return url

    def get_changeset(self, revision=None):

        """

        Returns ``MercurialChangeset`` object representing repository's

        changeset at the given ``revision``.

        """

        return changeset.MercurialChangeset(repository=self, revision=self._get_revision(revision))

    def get_changesets(self, start=None, end=None, start_date=None,

                       end_date=None, branch_name=None, reverse=False, max_revisions=None):

        """

        Returns iterator of ``MercurialChangeset`` objects from start to end

        (both are inclusive)

        :param start: None, str, int or mercurial lookup format

        :param end:  None, str, int or mercurial lookup format

        :param start_date:

        :param end_date:

        :param branch_name:

        """

        start_raw_id = self._get_revision(start)

        start_pos = None if start is None else self.revisions.index(start_raw_id)

        end_raw_id = self._get_revision(end)

        end_pos = None if end is None else self.revisions.index(end_raw_id)

        if start_pos is not None and end_pos is not None and start_pos > end_pos:

            raise RepositoryError("Start revision '%s' cannot be "

                                  "after end revision '%s'" % (start, end))

        if branch_name and branch_name not in self.allbranches:

            msg = "Branch %r not found in %s" % (branch_name, self.name)

            raise BranchDoesNotExistError(msg)

        if end_pos is not None:

            end_pos += 1

        # filter branches

        filter_ = []

        if branch_name:

            filter_.append(b'branch("%s")' % safe_bytes(branch_name))

        if start_date:

            filter_.append(b'date(">%s")' % safe_bytes(str(start_date)))

        if end_date:

            filter_.append(b'date("<%s")' % safe_bytes(str(end_date)))

        if filter_ or max_revisions:

            if filter_:

                revspec = b' and '.join(filter_)

            else:

                revspec = b'all()'

            if max_revisions:

                revspec = b'limit(%s, %d)' % (revspec, max_revisions)

            revisions = mercurial.scmutil.revrange(self._repo, [revspec])

        else:

            revisions = self.revisions

        # this is very much a hack to turn this into a list; a better solution

        # would be to get rid of this function entirely and use revsets

        revs = list(revisions)[start_pos:end_pos]

        if reverse:

            revs.reverse()

        return CollectionGenerator(self, revs)

    def get_diff_changesets(self, org_rev, other_repo, other_rev):

        """

        Returns lists of changesets that can be merged from this repo @org_rev

        to other_repo @other_rev

        ... and the other way

        ... and the ancestors that would be used for merge