| """Utilities for defining models |
| """ |
| |
| import operator |
| from typing import Any, Callable, Type |
| |
| |
| class KeyBasedCompareMixin: |
| """Provides comparison capabilities that is based on a key""" |
| |
| __slots__ = ["_compare_key", "_defining_class"] |
| |
| def __init__(self, key: Any, defining_class: Type["KeyBasedCompareMixin"]) -> None: |
| self._compare_key = key |
| self._defining_class = defining_class |
| |
| def __hash__(self) -> int: |
| return hash(self._compare_key) |
| |
| def __lt__(self, other: Any) -> bool: |
| return self._compare(other, operator.__lt__) |
| |
| def __le__(self, other: Any) -> bool: |
| return self._compare(other, operator.__le__) |
| |
| def __gt__(self, other: Any) -> bool: |
| return self._compare(other, operator.__gt__) |
| |
| def __ge__(self, other: Any) -> bool: |
| return self._compare(other, operator.__ge__) |
| |
| def __eq__(self, other: Any) -> bool: |
| return self._compare(other, operator.__eq__) |
| |
| def _compare(self, other: Any, method: Callable[[Any, Any], bool]) -> bool: |
| if not isinstance(other, self._defining_class): |
| return NotImplemented |
| |
| return method(self._compare_key, other._compare_key) |
