tiramisu/tiramisu/value.py

# -*- coding: utf-8 -*-
"takes care of the option's values and multi values"
# Copyright (C) 2013 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 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# 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
# ____________________________________________________________
from tiramisu.error import NoValueReturned, MandatoryError
from tiramisu.setting import owners

class OptionValues(object):
    def __init__(self, context):
        """
        Initializes the values's dict.

        :param context: the context is the home config's values and properties
        """
        self.owners = {}
        "Config's root indeed is in charge of the `Option()`'s values"
        self.values = {}
        self.previous_values = {}
        self.master_groups = {}
        self.context = context

    def _get_value(self, opt):
        "special case for the multis: they never return None"
        if opt.is_multi():
            if opt not in self.values:
                # FIXME : default value for a multi, we shall work on groups
                return Multi(opt.getdefault(), self.context, opt)
        else:
            if opt not in self.values:
                return opt.getdefault()
        return self.values[opt]

    def reset(self, opt):
        if opt in self.values:
            self.set_previous_value(opt)
            del(self.values[opt])
        self.setowner(opt, owners.default)

    def set_previous_value(self, opt):
        if opt in self.values:
            old_value = self.values[opt]
        else:
            old_value = None
        if type(old_value) == Multi:
           self.previous_values[opt] = list(old_value)
        else:
           self.previous_values[opt] = old_value

    def _is_empty(self, opt, value=None):
        "convenience method to know if an option is empty"
        if value is not None:
            return False
        if (not opt.is_multi() and self._get_value(opt) == None) or \
            (opt.is_multi() and (self._get_value(opt) == [] or \
                None in self._get_value(opt))):
            return True
        return False

    def _test_mandatory(self, opt, value=None):
        # mandatory options
        mandatory = self.context._cfgimpl_settings.mandatory
        if opt.is_mandatory() and mandatory:
            if self._is_empty(opt, value) and \
                    opt.is_empty_by_default():
                raise MandatoryError("option: {0} is mandatory "
                                      "and shall have a value".format(opt._name))

    def fill_multi(self, opt, result):
        """fills a multi option with default and calculated values
        """
        value = self._get_value(opt)
        if not isinstance(result, list):
            _result = [result]
        else:
            _result = result
        return Multi(_result, self.context, opt)

    def __getitem__(self, opt):
        # options with callbacks
        value = self._get_value(opt)
        if opt.has_callback():
            if (not opt.is_frozen() or \
                    not opt.is_forced_on_freeze()) and \
                    not opt.is_default_owner(self):
                return self._get_value(opt)
            try:
                result = opt.getcallback_value(
                        self.context)
            except NoValueReturned, err:
                pass
            else:
                if opt.is_multi():
                    value = fill_multi(opt, result)
                else:
                    # this result **shall not** be a list
                    if isinstance(result, list):
                        raise ConfigError('invalid calculated value returned '
                            'for option {0} : shall not be a list'.format(name))
                    value = result
                if value != None and not opt.validate(value,
                            self.context._cfgimpl_settings.validator):
                    raise ConfigError('invalid calculated value returned'
                        ' for option {0}'.format(name))
        # frozen and force default
        if not opt.has_callback() and opt.is_forced_on_freeze():
            value = opt.getdefault()
            if opt.is_multi():
                value = self.fill_multi(opt, value)
        self._test_mandatory(opt, value)
        return value

    def __setitem__(self, opt, value):
        self.set_previous_value(opt)
        self.values[opt] = value
        self.setowner(opt, self.context._cfgimpl_settings.getowner())

    def __contains__(self, opt):
        return opt in self.values
    #____________________________________________________________
    def setowner(self, opt, owner):
        if isinstance(owner, owners.Owner):
            self.owners[opt] = owner
        else:
            raise OptionValueError("Bad owner: " + str(owner))

    def getowner(self, opt):
        return self.owners.get(opt, owners.default)

# ____________________________________________________________
# multi types
class Multi(list):
    """multi options values container
    that support item notation for the values of multi options"""
    def __init__(self, lst, context, opt, multitype=settings.multitypes.default):
        """
        :param lst: the Multi wraps a list value
        :param context: the home config that has the settings and the values
        :param opt: the option object that have this Multi value
        """
        self.settings = context._cfgimpl_settings
        self.opt = opt
        self.values = context._cfgimpl_values
        self.multitype = multitype
        super(Multi, self).__init__(lst)

    def __setitem__(self, key, value):
        self._setvalue(value, key, who=self.settings.getowner())

    def append(self, value):
        """the list value can be updated (appened)
        only if the option is a master
        """
        self._setvalue(value, who=self.settings.getowner(self.opt))

    def _setvalue(self, value, key=None, who=None):
        if value != None:
            if not self.opt._validate(value):
                raise ConfigError("invalid value {0} "
                    "for option {1}".format(str(value), self.opt._name))
        oldvalue = list(self)
        if key is None:
            super(Multi, self).append(value)
        else:
            super(Multi, self).__setitem__(key, value)
        if who != None:
            if not isinstance(who, owners.Owner):
                raise TypeError("invalid owner {0} for the value {1}".format(
                                str(who), str(value)))
            self.values.setowner(self.opt, getattr(owners, who))
        self.values.previous_values[self.opt] = oldvalue

    def pop(self, key):
        """the list value can be updated (poped)
        only if the option is a master

        :param key: index of the element to pop
        :return: the requested element
        """
        self.values.setowner(opt, self.settings.get_owner())
        self.values.previous_values[self.opt] = list(self)
        return super(Multi, self).pop(key)