"""
pint.facets.group.registry
~~~~~~~~~~~~~~~~~~~~~~~~~~
:copyright: 2022 by Pint Authors, see AUTHORS for more details.
:license: BSD, see LICENSE for more details.
"""
from __future__ import annotations
from typing import TYPE_CHECKING, Dict, FrozenSet
from ... import errors
if TYPE_CHECKING:
from pint import Unit
from ...util import build_dependent_class, create_class_with_registry
from ..plain import PlainRegistry, UnitDefinition
from .definitions import GroupDefinition
from .objects import Group
[docs]class GroupRegistry(PlainRegistry):
"""Handle of Groups.
Group units
Capabilities:
- Register groups.
- Parse @group directive.
"""
# TODO: Change this to Group: Group to specify class
# and use introspection to get system class as a way
# to enjoy typing goodies
_group_class = Group
def __init__(self, **kwargs):
super().__init__(**kwargs)
#: Map group name to group.
#: :type: dict[ str | Group]
self._groups: Dict[str, Group] = {}
self._groups["root"] = self.Group("root")
def __init_subclass__(cls, **kwargs):
super().__init_subclass__()
cls.Group = build_dependent_class(cls, "Group", "_group_class")
def _init_dynamic_classes(self) -> None:
"""Generate subclasses on the fly and attach them to self"""
super()._init_dynamic_classes()
self.Group = create_class_with_registry(self, self.Group)
def _after_init(self) -> None:
"""Invoked at the end of ``__init__``.
- Create default group and add all orphan units to it
- Set default system
"""
super()._after_init()
#: Copy units not defined in any group to the default group
if "group" in self._defaults:
grp = self.get_group(self._defaults["group"], True)
group_units = frozenset(
[
member
for group in self._groups.values()
if group.name != "root"
for member in group.members
]
)
all_units = self.get_group("root", False).members
grp.add_units(*(all_units - group_units))
def _register_definition_adders(self) -> None:
super()._register_definition_adders()
self._register_adder(GroupDefinition, self._add_group)
def _add_unit(self, definition: UnitDefinition):
super()._add_unit(definition)
# TODO: delta units are missing
self.get_group("root").add_units(definition.name)
def _add_group(self, gd: GroupDefinition):
if gd.name in self._groups:
raise ValueError(f"Group {gd.name} already present in registry")
try:
# As a Group is a SharedRegistryObject
# it adds itself to the registry.
self.Group.from_definition(gd)
except KeyError as e:
raise errors.DefinitionSyntaxError(f"unknown dimension {e} in context")
[docs] def get_group(self, name: str, create_if_needed: bool = True) -> Group:
"""Return a Group.
Parameters
----------
name : str
Name of the group to be
create_if_needed : bool
If True, create a group if not found. If False, raise an Exception.
(Default value = True)
Returns
-------
Group
Group
"""
if name in self._groups:
return self._groups[name]
if not create_if_needed:
raise ValueError("Unknown group %s" % name)
return self.Group(name)
def _get_compatible_units(self, input_units, group) -> FrozenSet["Unit"]:
ret = super()._get_compatible_units(input_units, group)
if not group:
return ret
if group in self._groups:
members = self._groups[group].members
else:
raise ValueError("Unknown Group with name '%s'" % group)
return frozenset(ret & members)
