~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2007, 2008, 2009, 2011 Canonical Ltd

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

"""Library API versioning support.

Added in bzrlib 0.18 this allows export of compatibility information about

bzrlib. Please see doc/developers/api-versioning.txt for design details and

examples.

"""

from __future__ import absolute_import

import bzrlib

from bzrlib.errors import IncompatibleAPI

def get_current_api_version(object_with_api):

    """Return the API version tuple for object_with_api.

    :param object_with_api: An object to look for an API version on. If the

        object has a api_current_version attribute, that is used. Otherwise if

        there is a version_info attribute, its first three elements are used.

        Finally if there was no version_info attribute, the current api version

        of bzrlib itself is used.

    Added in bzrlib 0.18.

    """

    try:

        return object_with_api.api_current_version

    except AttributeError:

        try:

            return object_with_api.version_info[0:3]

        except AttributeError:

            return get_current_api_version(bzrlib)

def get_minimum_api_version(object_with_api):

    """Return the minimum API version supported by object_with_api.

    :param object_with_api: An object to look for an API version on. If the

        object has a api_minimum_version attribute, that is used. Otherwise the

        minimum api version of bzrlib itself is used.

    Added in bzrlib 0.18.

    """

    try:

        return object_with_api.api_minimum_version

    except AttributeError:

        return get_minimum_api_version(bzrlib)

def require_api(object_with_api, wanted_api):

    """Check if object_with_api supports the api version wanted_api.

    :param object_with_api: An object which exports an API minimum and current

        version. See get_minimum_api_version and get_current_api_version for

        details.

    :param wanted_api: The API version for which support is required.

    :return: None

    :raises IncompatibleAPI: When the wanted_api is not supported by

        object_with_api.

    Added in bzrlib 0.18.

    """

    current = get_current_api_version(object_with_api)

    minimum = get_minimum_api_version(object_with_api)

    if wanted_api < minimum or wanted_api > current:

        raise IncompatibleAPI(object_with_api, wanted_api, minimum, current)

def require_any_api(object_with_api, wanted_api_list):

    """Check if object_with_api supports the api version wanted_api.

    :param object_with_api: An object which exports an API minimum and current

        version. See get_minimum_api_version and get_current_api_version for

        details.

    :param wanted_api: A list of API versions, any of which being available is

        sufficent.

    :return: None

    :raises IncompatibleAPI: When the wanted_api is not supported by

        object_with_api.

    Added in bzrlib 1.9.

    """

    for api in wanted_api_list[:-1]:

        try:

            return require_api(object_with_api, api)

        except IncompatibleAPI:

            pass

    require_api(object_with_api, wanted_api_list[-1])