Source code for spinn_utilities.default_ordered_dict

# Copyright (c) 2019 The University of Manchester
#
# 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 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from collections import OrderedDict
from collections.abc import Callable


class DefaultOrderedDict(OrderedDict):
    # Source: https://stackoverflow.com/questions/6190331
    def __init__(self, default_factory=None, *args, **kwargs):
        # pylint: disable=keyword-arg-before-vararg
        if (default_factory is not None and
                not isinstance(default_factory, Callable)):
            raise TypeError('first argument must be callable')
        super().__init__(*args, **kwargs)
        self.default_factory = default_factory

    def __getitem__(self, key):
        try:
            return super().__getitem__(key)
        except KeyError:
            return self.__missing__(key)

    def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        self[key] = value = self.default_factory()
        return value

    def __reduce__(self):
        if self.default_factory is None:
            args = tuple()
        else:
            args = self.default_factory,
        return type(self), args, None, None, iter(self.items())

    def copy(self):
        return type(self)(self.default_factory, self.items())

    __copy__ = copy

    def __deepcopy__(self, memo):
        import copy
        return type(self)(self.default_factory,
                          copy.deepcopy(iter(self.items())))

    def __repr__(self):
        return 'DefaultOrderedDict(%s, %s)' % (
            self.default_factory, OrderedDict.__repr__(self))