tiramisu/tiramisu/config.py

# -*- coding: utf-8 -*-
# Copyright (C) 2012-2017 Team tiramisu (see AUTHORS for all contributors)
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by the
# Free Software Foundation, either version 3 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 Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# The original `Config` design model is unproudly borrowed from
# the rough pypy's guys: http://codespeak.net/svn/pypy/dist/pypy/config/
# the whole pypy projet is under MIT licence
# ____________________________________________________________
"options handler global entry point"
import weakref
import sys
from time import time
from copy import copy


from .error import PropertiesOptionError, ConfigError, ConflictError
from .option import OptionDescription, Option, SymLinkOption, \
    DynSymLinkOption, SynDynOptionDescription
from .option.baseoption import valid_name
from .setting import groups, Settings, default_encoding, undefined
from .storage import get_storages, set_storage, get_default_values_storages
from .value import Values  # , Multi
from .i18n import _


if sys.version_info[0] >= 3:  # pragma: no cover
    xrange = range


class SubConfig(object):
    """Sub configuration management entry.
    Tree if OptionDescription's responsability. SubConfig are generated
    on-demand. A Config is also a SubConfig.
    Root Config is call context below
    """
    __slots__ = ('_impl_context',
                 '_impl_descr',
                 '_impl_path',
                 '_impl_setting_properties',
                 '_impl_length')

    def __init__(self,
                 descr,
                 context,
                 setting_properties,
                 validate,
                 force_permissive,
                 subpath=None):
        """ Configuration option management master class

        :param descr: describes the configuration schema
        :type descr: an instance of ``option.OptionDescription``
        :param context: the current root config
        :type context: `Config`
        :type subpath: `str` with the path name
        """
        # main option description
        error = False
        if descr is not None and not isinstance(descr, OptionDescription) and \
                not isinstance(descr, SynDynOptionDescription):  # pragma: optional cover
            error = True
        if error:
            raise TypeError(_('descr must be an optiondescription, not {0}'
                             ).format(type(descr)))
        self._impl_descr = descr
        # sub option descriptions
        if not isinstance(context, weakref.ReferenceType):  # pragma: optional cover
            raise ValueError('context must be a Weakref')
        self._impl_context = context
        self._impl_path = subpath
        if setting_properties is not undefined:
            self._impl_setting_properties = setting_properties
        if setting_properties is not None and descr.impl_get_group_type() == groups.master:
            master = descr.getmaster()
            context_ = context()
            masterp = master.impl_getpath(context_)
            value = context_.cfgimpl_get_values().get_cached_value(master,
                                                                   masterp,
                                                                   setting_properties,
                                                                   validate=validate,
                                                                   force_permissive=force_permissive,
                                                                   self_properties=undefined,
                                                                   index=None)
            self._impl_length = len(value)

    def cfgimpl_get_length(self):
        return getattr(self, '_impl_length')

    def reset_one_option_cache(self,
                               values,
                               settings,
                               resetted_opts,
                               opt,
                               path):
        tresetted_opts = copy(resetted_opts)
        opt.reset_cache(opt,
                        path,
                        values,
                        'values',
                        tresetted_opts)
        tresetted_opts = copy(resetted_opts)
        opt.reset_cache(opt,
                        path,
                        settings,
                        'settings',
                        tresetted_opts)
        resetted_opts |= tresetted_opts
        for woption in opt._get_dependencies(self):
            option = woption()
            if option in resetted_opts:
                continue
            option_path = opt.impl_getpath(self)
            self.reset_one_option_cache(values,
                                        settings,
                                        resetted_opts,
                                        option,
                                        option_path)
            del option

    def cfgimpl_reset_cache(self,
                            only_expired=False,
                            opt=None,
                            path=None,
                            resetted_opts=None):
        """reset all settings in cache

        :param only_expired: if True reset only expired cached values
        :type only_expired: boolean
        """

        def reset_expired_cache():
            # reset cache for expired cache value ony
            datetime = int(time())
            values._p_.reset_expired_cache(datetime)
            settings._p_.reset_expired_cache(datetime)

        def reset_all_cache():
            values._p_.reset_all_cache()
            settings._p_.reset_all_cache()

        if resetted_opts is None:
            resetted_opts = set()

        context = self._cfgimpl_get_context()
        values = context.cfgimpl_get_values()
        settings = context.cfgimpl_get_settings()

        if not None in (opt, path):
            if opt not in resetted_opts:
                self.reset_one_option_cache(values,
                                            settings,
                                            resetted_opts,
                                            opt,
                                            path)

        elif only_expired:
            reset_expired_cache()
        else:
            reset_all_cache()

    def cfgimpl_get_home_by_path(self,
                                 path,
                                 setting_properties,
                                 validate_properties=True,
                                 force_permissive=False):
        """:returns: tuple (config, name)"""
        path = path.split('.')
        for step in path[:-1]:
            self = self.getattr(step,
                                force_permissive=force_permissive,
                                validate_properties=validate_properties,
                                setting_properties=setting_properties)
        return self, path[-1]

    # ______________________________________________________________________
#    def __iter__(self, force_permissive=False):
#        """Pythonesque way of parsing group's ordered options.
#        iteration only on Options (not OptionDescriptions)"""
#        setting_properties = self.cfgimpl_get_context().cfgimpl_get_settings().get_context_properties()
#        for child in self.cfgimpl_get_description().impl_getchildren(context=self._cfgimpl_get_context()):
#            if not child.impl_is_optiondescription():
#                try:
#                    name = child.impl_getname()
#                    yield name, self.getattr(name,
#                                             force_permissive=force_permissive,
#                                             setting_properties=setting_properties)
#                except GeneratorExit:  # pragma: optional cover
#                    if sys.version_info[0] < 3:
#                        raise StopIteration
#                    else:
#                        raise GeneratorExit()
#                except PropertiesOptionError:  # pragma: optional cover
#                    pass  # option with properties
#
#    def iter_all(self, force_permissive=False):
#        """A way of parsing options **and** groups.
#        iteration on Options and OptionDescriptions."""
#        for child in self.cfgimpl_get_description().impl_getchildren():
#            try:
#                yield child.impl_getname(), self.getattr(child.impl_getname(),
#                                                         force_permissive=force_permissive)
#            except GeneratorExit:  # pragma: optional cover
#                if sys.version_info[0] < 3:
#                    raise StopIteration
#                else:
#                    raise GeneratorExit()
#            except PropertiesOptionError:  # pragma: optional cover
#                pass  # option with properties

    def iter_groups(self,
                    setting_properties,
                    group_type=None,
                    force_permissive=False):
        """iteration on groups objects only.
        All groups are returned if `group_type` is `None`, otherwise the groups
        can be filtered by categories (families, or whatever).

        :param group_type: if defined, is an instance of `groups.GroupType`
                           or `groups.MasterGroupType` that lives in
                           `setting.groups`
        """
        if group_type is not None and not isinstance(group_type,
                                                     groups.GroupType):  # pragma: optional cover
            raise TypeError(_("unknown group_type: {0}").format(group_type))
        context = self._cfgimpl_get_context()
        setting_properties = context.cfgimpl_get_settings().get_context_properties()
        for child in self.cfgimpl_get_description().impl_getchildren(context=context,
                                                                     setting_properties=setting_properties):
            if child.impl_is_optiondescription():
                try:
                    if group_type is None or (group_type is not None and
                                              child.impl_get_group_type()
                                              == group_type):
                        name = child.impl_getname()
                        yield name, self.getattr(name,
                                                 force_permissive=force_permissive,
                                                 setting_properties=setting_properties)
                except GeneratorExit:  # pragma: optional cover
                    if sys.version_info[0] < 3:
                        raise StopIteration
                    else:
                        raise GeneratorExit()
                except PropertiesOptionError:  # pragma: optional cover
                    pass
    # ______________________________________________________________________

#    def __str__(self):
#        "Config's string representation"
#        lines = []
#        for name, grp in self.iter_groups():
#            lines.append("[{0}]".format(name))
#        for name, value in self:
#            try:
#                lines.append("{0} = {1}".format(name, value))
#            except UnicodeEncodeError:  # pragma: optional cover
#                lines.append("{0} = {1}".format(name,
#                                                value.encode(default_encoding)))
#        return '\n'.join(lines)
#
#    __repr__ = __str__

    def _cfgimpl_get_context(self):
        """context could be None, we need to test it
        context is None only if all reference to `Config` object is deleted
        (for example we delete a `Config` and we manipulate a reference to
        old `SubConfig`, `Values`, `Multi` or `Settings`)
        """
        context = self._impl_context()
        if context is None:  # pragma: optional cover
            raise ConfigError(_('the context does not exist anymore'))
        return context

    def cfgimpl_get_context(self):
        return self._cfgimpl_get_context()

    def cfgimpl_get_description(self):
        if self._impl_descr is None:  # pragma: optional cover
            raise ConfigError(_('no option description found for this config'
                                ' (may be GroupConfig)'))
        else:
            return self._impl_descr

    def cfgimpl_get_settings(self):
        return self._cfgimpl_get_context()._impl_settings

    def cfgimpl_get_values(self):
        return self._cfgimpl_get_context()._impl_values

    # ____________________________________________________________
    # attribute methods
    def __setattr__(self, name, value):
        "attribute notation mechanism for the setting of the value of an option"
        self.setattr(name,
                     value)

    def setattr(self,
                name,
                value,
                force_permissive=False,
                index=None,
                setting_properties=None,
                _commit=True):

        if name.startswith('_impl_'):
            return object.__setattr__(self,
                                      name,
                                      value)
        context = self._cfgimpl_get_context()
        if '.' in name:  # pragma: optional cover
            self, name = self.cfgimpl_get_home_by_path(name,
                                                       force_permissive=force_permissive,
                                                       setting_properties=setting_properties)
        child = self.cfgimpl_get_description().impl_getchild(name,
                                                             setting_properties,
                                                             self)
        if isinstance(child, (OptionDescription, SynDynOptionDescription)):
            raise TypeError(_("can't assign to an OptionDescription"))  # pragma: optional cover
        elif child.impl_is_symlinkoption():
            raise TypeError(_("can't assign to a SymLinkOption"))
        else:
            self.cfgimpl_get_description().impl_validate_value(child,
                                                               value,
                                                               self)
            subpath = self._get_subpath(name)
            return self.cfgimpl_get_values().setvalue(child,
                                                      value,
                                                      subpath,
                                                      force_permissive,
                                                      index,
                                                      setting_properties,
                                                      _commit)

    def delattr(self,
                name,
                index=None,
                force_permissive=False,
                setting_properties=None,
                validate=True):

        context = self._cfgimpl_get_context()
        if '.' in name:  # pragma: optional cover
            self, name = self.cfgimpl_get_home_by_path(name,
                                                       force_permissive=force_permissive,
                                                       setting_properties=setting_properties)
        child = self.cfgimpl_get_description().impl_getchild(name,
                                                             setting_properties,
                                                             self)
        if isinstance(child, (OptionDescription, SynDynOptionDescription)):
            raise TypeError(_("can't delete an OptionDescription"))  # pragma: optional cover
        elif child.impl_is_symlinkoption():
            raise TypeError(_("can't delete a SymLinkOption"))
        subpath = self._get_subpath(name)
        values = self.cfgimpl_get_values()
        if index is not None:
            if child.impl_is_master_slaves('master'):
                values.reset_master(self,
                                    child,
                                    subpath,
                                    index,
                                    force_permissive,
                                    setting_properties)
            elif child.impl_is_master_slaves('slave'):
                values.reset_slave(child,
                                   subpath,
                                   index,
                                   setting_properties,
                                   force_permissive=force_permissive,
                                   validate=validate)
            else:
                raise ValueError(_("can delete value with index only with a master or a slave"))
        else:
            values.reset(child,
                         subpath,
                         setting_properties,
                         force_permissive=force_permissive,
                         validate=validate)

    def _get_subpath(self, name):
        if self._impl_path is None:
            subpath = name
        else:
            subpath = self._impl_path + '.' + name
        return subpath

    def getattr(self,
                name,
                setting_properties,
                force_permissive=False,
                validate=True,
                validate_properties=True,
                index=None,
                returns_option=False):
        """
        attribute notation mechanism for accessing the value of an option
        :param name: attribute name
        :return: option's value if name is an option name, OptionDescription
                 otherwise
        """
        if '.' in name:
            self, name = self.cfgimpl_get_home_by_path(name,
                                                       force_permissive=force_permissive,
                                                       validate_properties=validate_properties,
                                                       setting_properties=setting_properties)

        context = self._cfgimpl_get_context()
        option = self.cfgimpl_get_description().impl_getchild(name,
                                                              setting_properties,
                                                              self)
        if option.impl_is_symlinkoption():
            if returns_option is True:
                return option
            path = context.cfgimpl_get_description().impl_get_path_by_opt(option.impl_getopt())
            return context.getattr(path,
                                   validate=validate,
                                   validate_properties=validate_properties,
                                   force_permissive=force_permissive,
                                   setting_properties=setting_properties,
                                   index=index)

        subpath = self._get_subpath(name)
        if setting_properties:
            self.cfgimpl_get_settings().validate_properties(option,
                                                            subpath,
                                                            setting_properties,
                                                            index=index,
                                                            force_permissive=force_permissive)
        if option.impl_is_optiondescription():
            if returns_option is True:
                return option
            return SubConfig(option,
                             self._impl_context,
                             setting_properties,
                             validate,
                             force_permissive,
                             subpath)

        if option.impl_is_master_slaves('slave'):
            if index is None:
                raise IndexError(_('index is mandatory for the slave "{}"'
                                   '').format(subpath))
            length = self.cfgimpl_get_length()
            if index >= length:
                raise IndexError(_('index ({}) is higher than the master length ({}) '
                                   'for "{}"').format(index,
                                                      length,
                                                      subpath))
        elif index:
            raise IndexError(_('index is forbidden for the not slave "{}"'
                               '').format(subpath))
        if validate:
            self.cfgimpl_get_description().impl_validate(context,
                                                         force_permissive,
                                                         setting_properties)

        if returns_option is True:
            return option
        return self.cfgimpl_get_values().get_cached_value(option,
                                                          subpath,
                                                          setting_properties,
                                                          validate=validate,
                                                          force_permissive=force_permissive,
                                                          index=index)

    def find(self,
             setting_properties,
             bytype=None,
             byname=None,
             byvalue=undefined,
             type_='option',
             check_properties=True,
             force_permissive=False):
        """
            finds a list of options recursively in the config

            :param bytype: Option class (BoolOption, StrOption, ...)
            :param byname: filter by Option.impl_getname()
            :param byvalue: filter by the option's value
            :returns: list of matching Option objects
        """
        return self._cfgimpl_get_context()._find(bytype,
                                                 byname,
                                                 byvalue,
                                                 setting_properties=setting_properties,
                                                 first=False,
                                                 type_=type_,
                                                 _subpath=self.cfgimpl_get_path(False),
                                                 check_properties=check_properties,
                                                 force_permissive=force_permissive)

    def find_first(self,
                   setting_properties,
                   bytype=None,
                   byname=None,
                   byvalue=undefined,
                   type_='option',
                   raise_if_not_found=True,
                   check_properties=True,
                   force_permissive=False):
        """
            finds an option recursively in the config

            :param bytype: Option class (BoolOption, StrOption, ...)
            :param byname: filter by Option.impl_getname()
            :param byvalue: filter by the option's value
            :returns: list of matching Option objects
        """
        return self._cfgimpl_get_context()._find(bytype,
                                                 byname,
                                                 byvalue,
                                                 setting_properties=setting_properties,
                                                 first=True,
                                                 type_=type_,
                                                 _subpath=self.cfgimpl_get_path(False),
                                                 raise_if_not_found=raise_if_not_found,
                                                 check_properties=check_properties,
                                                 force_permissive=force_permissive)

    def _find(self,
              bytype,
              byname,
              byvalue,
              first,
              type_='option',
              _subpath=None,
              check_properties=True,
              raise_if_not_found=True,
              force_permissive=False,
              only_path=undefined,
              only_option=undefined,
              setting_properties=None):
        """
        convenience method for finding an option that lives only in the subtree

        :param first: return only one option if True, a list otherwise
        :return: find list or an exception if nothing has been found
        """
        def _filter_by_value():
            if byvalue is undefined:
                return True
            try:
                value = self.getattr(path,
                                     force_permissive=force_permissive,
                                     setting_properties=setting_properties)
            except PropertiesOptionError:
                return False
            if isinstance(value, list):
                return byvalue in value
            else:
                return value == byvalue

        if type_ not in ('option', 'path', 'value'):  # pragma: optional cover
            raise ValueError(_('unknown type_ type {0}'
                               'for _find').format(type_))
        find_results = []
        # if value and/or check_properties are set, need all avalaible option
        # If first one has no good value or not good property check second one
        # and so on
        only_first = first is True and byvalue is undefined and \
            check_properties is None
        if only_path is not undefined:
            options = [(only_path, only_option)]
        else:
            options = self.cfgimpl_get_description().impl_get_options_paths(bytype,
                                                                            byname,
                                                                            _subpath,
                                                                            only_first,
                                                                            self._cfgimpl_get_context(),
                                                                            setting_properties)
        for path, option in options:
            if not _filter_by_value():
                continue
            #remove option with propertyerror, ...
            if check_properties:
                try:
                    self.unwrap_from_path(path,
                                          setting_properties=setting_properties,
                                          force_permissive=force_permissive)
                except PropertiesOptionError:
                    continue
            if type_ == 'value':
                retval = self.getattr(path,
                                      force_permissive=force_permissive,
                                      setting_properties=setting_properties)
            elif type_ == 'path':
                retval = path
            elif type_ == 'option':
                retval = option
            if first:
                return retval
            else:
                find_results.append(retval)
        return self._find_return_results(find_results,
                                         raise_if_not_found)

    def _find_return_results(self,
                             find_results,
                             raise_if_not_found):
        if find_results == []:  # pragma: optional cover
            if raise_if_not_found:
                raise AttributeError(_("no option found in config"
                                       " with these criteria"))
        else:
            return find_results

    def make_dict(self,
                  setting_properties,
                  flatten=False,
                  _currpath=None,
                  withoption=None,
                  withvalue=undefined,
                  force_permissive=False,
                  fullpath=False):
        """exports the whole config into a `dict`, for example:

        >>> print(cfg.make_dict())
        {'od2.var4': None, 'od2.var5': None, 'od2.var6': None}



        :param flatten: returns a dict(name=value) instead of a dict(path=value)
                        ::

                            >>> print(cfg.make_dict(flatten=True))
                            {'var5': None, 'var4': None, 'var6': None}

        :param withoption: returns the options that are present in the very same
                           `OptionDescription` than the `withoption` itself::

                                >>> print(cfg.make_dict(withoption='var1'))
                                {'od2.var4': None, 'od2.var5': None,
                                'od2.var6': None,
                                'od2.var1': u'value',
                                'od1.var1': None,
                                'od1.var3': None,
                                'od1.var2': None}

        :param withvalue: returns the options that have the value `withvalue`
                          ::

                            >>> print(c.make_dict(withoption='var1',
                                                  withvalue=u'value'))
                            {'od2.var4': None,
                            'od2.var5': None,
                            'od2.var6': None,
                            'od2.var1': u'value'}

        :returns: dict of Option's name (or path) and values
        """
        pathsvalues = []
        if _currpath is None:
            _currpath = []
        if withoption is None and withvalue is not undefined:  # pragma: optional cover
            raise ValueError(_("make_dict can't filtering with value without "
                               "option"))
        if withoption is not None:
            context = self._cfgimpl_get_context()
            for path in context._find(bytype=None,
                                      byname=withoption,
                                      byvalue=withvalue,
                                      first=False,
                                      type_='path',
                                      _subpath=self.cfgimpl_get_path(False),
                                      force_permissive=force_permissive,
                                      setting_properties=setting_properties):
                path = '.'.join(path.split('.')[:-1])
                opt = context.unwrap_from_path(path, 
                                               orce_permissive=True)
                mypath = self.cfgimpl_get_path()
                if mypath is not None:
                    if mypath == path:
                        withoption = None
                        withvalue = undefined
                        break
                    else:
                        tmypath = mypath + '.'
                        if not path.startswith(tmypath):  # pragma: optional cover
                            raise AttributeError(_('unexpected path {0}, '
                                                   'should start with {1}'
                                                   '').format(path, mypath))
                        path = path[len(tmypath):]
                self._make_sub_dict(opt,
                                    path,
                                    pathsvalues,
                                    _currpath,
                                    flatten,
                                    force_permissive=force_permissive,
                                    setting_properties=setting_properties,
                                    fullpath=fullpath)
        #withoption can be set to None below !
        if withoption is None:
            for opt in self.cfgimpl_get_description().impl_getchildren(setting_properties):
                path = opt.impl_getname()
                self._make_sub_dict(opt,
                                    path,
                                    pathsvalues,
                                    _currpath,
                                    flatten,
                                    force_permissive=force_permissive,
                                    setting_properties=setting_properties,
                                    fullpath=fullpath)
        if _currpath == []:
            options = dict(pathsvalues)
            return options
        return pathsvalues

    def _make_sub_dict(self,
                       option,
                       path,
                       pathsvalues,
                       _currpath,
                       flatten,
                       setting_properties,
                       force_permissive=False,
                       fullpath=False):
        try:
            if not option.impl_is_optiondescription() and option.impl_is_master_slaves('slave'):
                ret = []
                length = self.cfgimpl_get_length()
                if length:
                    for idx in range(length):
                        ret.append(self.getattr(path,
                                                index=idx,
                                                force_permissive=force_permissive,
                                                setting_properties=setting_properties))
                elif setting_properties:
                    self.cfgimpl_get_settings().validate_properties(option,
                                                                    path,
                                                                    setting_properties,
                                                                    force_permissive=force_permissive)
            else:
                ret = self.getattr(path,
                                   force_permissive=force_permissive,
                                   setting_properties=setting_properties)
        except PropertiesOptionError:
            pass
        else:
            if option.impl_is_optiondescription():
                pathsvalues += ret.make_dict(setting_properties,
                                             flatten=flatten,
                                             _currpath=_currpath + path.split('.'),
                                             force_permissive=force_permissive,
                                             fullpath=fullpath)
            else:
                if flatten:
                    name = option.impl_getname()
                elif fullpath:
                    #FIXME
                    #root_path = self.cfgimpl_get_path()
                    #if root_path is None:
                    #    name = opt.impl_getname()
                    #else:
                    #    name = '.'.join([root_path, opt.impl_getname()])
                    name = self._get_subpath(name)
                else:
                    name = '.'.join(_currpath + [option.impl_getname()])
                pathsvalues.append((name, ret))

    def cfgimpl_get_path(self,
                         dyn=True):
        descr = self.cfgimpl_get_description()
        if not dyn and descr.impl_is_dynoptiondescription():
            context_descr = self._cfgimpl_get_context().cfgimpl_get_description()
            return context_descr.impl_get_path_by_opt(descr.impl_getopt())
        return self._impl_path


class _CommonConfig(SubConfig):
    "abstract base class for the Config, GroupConfig and the MetaConfig"
    __slots__ = ('_impl_values', '_impl_settings', '_impl_meta', '_impl_test')

    def _impl_build_all_caches(self,
                               force_store_values):
        descr = self.cfgimpl_get_description()
        if not descr.impl_already_build_caches():
            descr._build_cache_option()
            descr._build_cache(self)
        descr.impl_build_force_store_values(self,
                                            force_store_values)

    def read_only(self):
        "read only is a global config's setting, see `settings.py`"
        self.cfgimpl_get_settings().read_only()

    def read_write(self):
        "read write is a global config's setting, see `settings.py`"
        self.cfgimpl_get_settings().read_write()

    def getowner(self,
                 opt,
                 index=None,
                 force_permissive=False):
        """convenience method to retrieve an option's owner
        from the config itself
        """
        if not isinstance(opt, Option) and \
                not isinstance(opt, SymLinkOption) and \
                not isinstance(opt, DynSymLinkOption):  # pragma: optional cover
            raise TypeError(_('opt in getowner must be an option not {0}'
                              '').format(type(opt)))
        return self.cfgimpl_get_values().getowner(opt,
                                                  index=index,
                                                  force_permissive=force_permissive)

    def unwrap_from_path(self,
                         path,
                         setting_properties=None,
                         force_permissive=False,
                         index=None,
                         validate=True,
                         validate_properties=True):
        """convenience method to extract and Option() object from the Config()
        and it is **fast**: finds the option directly in the appropriate
        namespace

        :returns: Option()
        """
        if '.' in path:
            self, path = self.cfgimpl_get_home_by_path(path,
                                                       force_permissive=force_permissive,
                                                       validate_properties=validate_properties,
                                                       setting_properties=setting_properties)
        option = self.cfgimpl_get_description().impl_getchild(path,
                                                              setting_properties,
                                                              self)
        if not validate_properties:
            return option
        else:
            if option.impl_is_symlinkoption():
                true_option = option.impl_getopt()
                true_path = true_option.impl_getpath(self._cfgimpl_get_context())
                self, path = self.cfgimpl_get_context().cfgimpl_get_home_by_path(true_path,
                                                                                 force_permissive=force_permissive,
                                                                                 validate_properties=validate_properties,
                                                                                 setting_properties=setting_properties)
            else:
                true_option = option
                true_path = path
            if index is None and true_option.impl_is_master_slaves('slave'):
                subpath = self._get_subpath(true_path)
                self.cfgimpl_get_settings().validate_properties(true_option,
                                                                subpath,
                                                                setting_properties,
                                                                force_permissive=force_permissive)
                return option
            self.getattr(path,
                         validate=validate,
                         force_permissive=force_permissive,
                         index=index,
                         setting_properties=setting_properties,
                         validate_properties=validate_properties,
                         returns_option=True)
            return option

    def cfgimpl_get_path(self, dyn=True):
        return None

    def cfgimpl_get_meta(self):
        if self._impl_meta is not None:
            return self._impl_meta()

    # information
    def impl_set_information(self, key, value):
        """updates the information's attribute

        :param key: information's key (ex: "help", "doc"
        :param value: information's value (ex: "the help string")
        """
        self._impl_values.set_information(key, value)

    def impl_get_information(self, key, default=undefined):
        """retrieves one information's item

        :param key: the item string (ex: "help")
        """
        return self._impl_values.get_information(key, default)

    def impl_del_information(self, key, raises=True):
        self._impl_values.del_information(key, raises)

    def __getstate__(self):
        raise NotImplementedError()

    def _gen_fake_values(self):
        fake_config = Config(self._impl_descr,
                             persistent=False,
                             force_values=get_default_values_storages(),
                             force_settings=self.cfgimpl_get_settings())
        fake_config.cfgimpl_get_values()._p_.importation(self.cfgimpl_get_values()._p_.exportation(fake=True))
        return fake_config

    def duplicate(self,
                  session_id=None,
                  force_values=None,
                  force_settings=None):
        config = Config(self._impl_descr,
                        _duplicate=True,
                        session_id=session_id,
                        force_values=force_values,
                        force_settings=force_settings)
        config.cfgimpl_get_values()._p_.importation(self.cfgimpl_get_values()._p_.exportation())
        config.cfgimpl_get_settings()._p_.set_modified_properties(self.cfgimpl_get_settings(
            )._p_.get_modified_properties())
        config.cfgimpl_get_settings()._pp_.set_modified_permissives(self.cfgimpl_get_settings(
            )._pp_.get_modified_permissives())
        return config


# ____________________________________________________________
class Config(_CommonConfig):
    "main configuration management entry"
    __slots__ = ('__weakref__', '_impl_test', '_impl_name')

    def __init__(self,
                 descr,
                 session_id=None,
                 persistent=False,
                 force_values=None,
                 force_settings=None,
                 _duplicate=False,
                 _force_store_values=True):
        """ Configuration option management master class

        :param descr: describes the configuration schema
        :type descr: an instance of ``option.OptionDescription``
        :param context: the current root config
        :type context: `Config`
        :param session_id: session ID is import with persistent Config to
        retrieve good session
        :type session_id: `str`
        :param persistent: if persistent, don't delete storage when leaving
        :type persistent: `boolean`
        """
        if force_settings is not None and force_values is not None:
            if isinstance(force_settings, tuple):
                self._impl_settings = Settings(self,
                                               force_settings[0],
                                               force_settings[1])
            else:
                self._impl_settings = force_settings
            self._impl_values = Values(self,
                                       force_values)
        else:
            properties, permissives, values, session_id = get_storages(self,
                                                                       session_id,
                                                                       persistent)
            if not valid_name(session_id):  # pragma: optional cover
                raise ValueError(_("invalid session ID: {0} for config").format(session_id))
            self._impl_settings = Settings(self,
                                           properties,
                                           permissives)
            self._impl_values = Values(self,
                                       values)
        super(Config, self).__init__(descr,
                                     weakref.ref(self),
                                     undefined,
                                     True,
                                     False)
        self._impl_meta = None
        #undocumented option used only in test script
        self._impl_test = False
        if _duplicate is False and (force_settings is None or force_values is None):
            self._impl_build_all_caches(_force_store_values)
        self._impl_name = session_id

    def impl_getname(self):
        return self._impl_name

    def impl_getsessionid(self):
        return self._impl_values._p_._storage.session_id


class GroupConfig(_CommonConfig):
    __slots__ = ('__weakref__',
                 '_impl_children',
                 '_impl_name')

    def __init__(self,
                 children,
                 session_id=None,
                 persistent=False,
                 _descr=None):
        if not isinstance(children, list):
            raise ValueError(_("groupconfig's children must be a list"))
        names = []
        for child in children:
            if not isinstance(child,
                              _CommonConfig):
                raise ValueError(_("groupconfig's children must be Config, MetaConfig or GroupConfig"))
            name_ = child._impl_name
            names.append(name_)
        if len(names) != len(set(names)):
            for idx in xrange(1, len(names) + 1):
                name = names.pop(0)
                if name in names:
                    raise ConflictError(_('config name must be uniq in '
                                          'groupconfig for {0}').format(name))
        self._impl_children = children
        properties, permissives, values, session_id = get_storages(self,
                                                                   session_id,
                                                                   persistent)
        self._impl_settings = Settings(self,
                                       properties,
                                       permissives)
        self._impl_values = Values(self, values)
        super(GroupConfig, self).__init__(_descr,
                                          weakref.ref(self),
                                          undefined,
                                          True,
                                          False)
        self._impl_meta = None
        #undocumented option used only in test script
        self._impl_test = False
        self._impl_name = session_id

    def cfgimpl_get_children(self):
        return self._impl_children

    def cfgimpl_reset_cache(self,
                            only_expired=False,
                            opt=None,
                            path=None,
                            resetted_opts=set()):
        if isinstance(self, MetaConfig):
            super(GroupConfig, self).cfgimpl_reset_cache(only_expired=only_expired,
                                                         opt=opt,
                                                         path=path,
                                                         resetted_opts=copy(resetted_opts))
        for child in self._impl_children:
            child.cfgimpl_reset_cache(only_expired=only_expired,
                                      opt=opt,
                                      path=path,
                                      resetted_opts=copy(resetted_opts))

    def set_value(self, path, value, _commit=True):
        """Setattr not in current GroupConfig, but in each children
        """
        ret = []
        for child in self._impl_children:
            if isinstance(child, MetaConfig):
                ret.extend(child.set_value(path,
                                           value,
                                           only_config=True,
                                           _commit=False))
            elif isinstance(child, GroupConfig):
                ret.extend(child.set_value(path,
                                           value,
                                           _commit=False))
            else:
                childret = child.setattr(path,
                                         value,
                                         not_raises=True,
                                         _commit=False)
                if childret is not None:
                    ret.append(childret)
        if _commit:
            self.cfgimpl_get_values()._p_.commit()
        return ret


    def find_firsts(self,
                    byname=None,
                    bypath=undefined,
                    byoption=undefined,
                    byvalue=undefined,
                    raise_if_not_found=True,
                    _sub=False,
                    check_properties=True):
        """Find first not in current GroupConfig, but in each children
        """
        ret = []

        #if MetaConfig, all children have same OptionDescription in context
        #so search only one time the option for all children
        if bypath is undefined and byname is not None and \
                isinstance(self,
                           MetaConfig):
            bypath = self._find(bytype=None,
                                byvalue=undefined,
                                byname=byname,
                                first=True,
                                type_='path',
                                check_properties=None,
                                raise_if_not_found=raise_if_not_found)
            byname = None
            byoption = self.cfgimpl_get_description().impl_get_opt_by_path(bypath)

        for child in self._impl_children:
            if isinstance(child, GroupConfig):
                ret.extend(child.find_firsts(byname=byname,
                                             bypath=bypath,
                                             byoption=byoption,
                                             byvalue=byvalue,
                                             check_properties=check_properties,
                                             raise_if_not_found=False,
                                             _sub=True))
            elif child._find(None,
                             byname,
                             byvalue,
                             first=True,
                             type_='path',
                             raise_if_not_found=False,
                             check_properties=check_properties,
                             only_path=bypath,
                             only_option=byoption):
                ret.append(child)
        if _sub:
            return ret
        else:
            return GroupConfig(self._find_return_results(ret,
                                                         raise_if_not_found))

    def __str__(self):
        ret = ''
        for child in self._impl_children:
            ret += "({0})\n".format(child._impl_name)
        if self._impl_descr is not None:
            ret += super(GroupConfig, self).__str__()
        return ret

    __repr__ = __str__

    def getconfig(self,
                  name):
        for child in self._impl_children:
            if name == child.impl_getname():
                return child
        raise ConfigError(_('unknown config {}').format(name))


class MetaConfig(GroupConfig):
    __slots__ = tuple()

    def __init__(self,
                 children,
                 session_id=None,
                 persistent=False,
                 optiondescription=None,
                 _force_store_values=True):
        descr = None
        if optiondescription is not None:
            new_children = []
            for child_session_id in children:
                new_children.append(Config(optiondescription,
                                           persistent=persistent,
                                           session_id=child_session_id,
                                           _force_store_values=_force_store_values))
            children = new_children
        for child in children:
            if not isinstance(child, _CommonConfig):
                raise TypeError(_("metaconfig's children "
                                  "should be config, not {0}"
                                  ).format(type(child)))
            if child.cfgimpl_get_meta() is not None:
                raise ValueError(_("child has already a metaconfig's"))
            if descr is None:
                descr = child.cfgimpl_get_description()
            elif not descr is child.cfgimpl_get_description():
                raise ValueError(_('all config in metaconfig must '
                                   'have the same optiondescription'))
            child._impl_meta = weakref.ref(self)

        super(MetaConfig, self).__init__(children,
                                         session_id,
                                         persistent,
                                         descr)

    def set_value(self,
                  path,
                  value,
                  force_default=False,
                  force_dont_change_value=False,
                  force_default_if_same=False,
                  only_config=False,
                  _commit=True):
        """only_config: could be set if you want modify value in all Config included in
                        this MetaConfig
        """
        if only_config:
            if force_default or force_default_if_same or force_dont_change_value:
                raise ValueError(_('force_default, force_default_if_same or '
                                   'force_dont_change_value cannot be set with'
                                   ' only_config'))
            return super(MetaConfig, self).set_value(path,
                                                     value,
                                                     _commit=_commit)
        ret = []
        if force_default or force_default_if_same or force_dont_change_value:
            if force_default and force_dont_change_value:
                raise ValueError(_('force_default and force_dont_change_value'
                                   ' cannot be set together'))
            opt = self.cfgimpl_get_description().impl_get_opt_by_path(path)
            setting_properties = self.cfgimpl_get_settings()._getproperties(read_write=False)
            for child in self._impl_children:
                if force_default_if_same or force_default:
                    if force_default_if_same:
                        if not child.cfgimpl_get_values()._contains(path):
                            child_value = undefined
                        else:
                            child_value = child.getattr(path)
                    if force_default or value == child_value:
                        child.cfgimpl_get_values().reset(opt,
                                                         path,
                                                         setting_properties,
                                                         validate=False,
                                                         _commit=False)
                        continue
                if force_dont_change_value:
                    child_value = child.getattr(path,
                                                setting_properties=setting_properties)
                    if isinstance(child_value, Exception):
                        ret.append(child_value)
                    elif value != child_value:
                        childret = child.setattr(path,
                                                 child_value,
                                                 _commit=False,
                                                 not_raises=True)
                        if childret is not None:  # pragma: no cover
                            ret.append(childret)

        self.setattr(path,
                     value,
                     _commit=_commit)
        return ret

    def reset(self, path):
        opt = self.cfgimpl_get_description().impl_get_opt_by_path(path)
        setting_properties = self.cfgimpl_get_settings()._getproperties(read_write=False)
        for child in self._impl_children:
            child.cfgimpl_get_values().reset(opt,
                                             path,
                                             setting_properties,
                                             validate=False,
                                             _commit=False)
        self.cfgimpl_get_values().reset(opt,
                                        path,
                                        setting_properties,
                                        validate=False)

    def new_config(self,
                   session_id,
                   persistent=False):
        config = Config(self._impl_descr,
                        session_id=session_id,
                        persistent=persistent)

        if config._impl_name in [child._impl_name for child in self._impl_children]:  # pragma: no cover
            raise ConflictError(_('config name must be uniq in '
                                  'groupconfig for {0}').format(config._impl_name))
        config._impl_meta = weakref.ref(self)
        self._impl_children.append(config)
        return config