|
| 1 | +###################################################################### |
| 2 | +# |
| 3 | +# File: b2/_internal/class_registry.py |
| 4 | +# |
| 5 | +# Copyright 2026 Backblaze Inc. All Rights Reserved. |
| 6 | +# |
| 7 | +# License https://www.backblaze.com/using_b2_code.html |
| 8 | +# |
| 9 | +###################################################################### |
| 10 | +from __future__ import annotations |
| 11 | + |
| 12 | +from collections import OrderedDict |
| 13 | +from collections.abc import Callable, Hashable, Iterable, Iterator |
| 14 | +from typing import Any |
| 15 | + |
| 16 | + |
| 17 | +class RegistryKeyError(KeyError): |
| 18 | + """Raised when a registry lookup fails.""" |
| 19 | + |
| 20 | + |
| 21 | +class ClassRegistry: |
| 22 | + """Registry with decorator-based class registration and instantiation.""" |
| 23 | + |
| 24 | + def __init__(self, attr_name: str | None = None, unique: bool = False) -> None: |
| 25 | + self.attr_name = attr_name |
| 26 | + self.unique = unique |
| 27 | + self._registry: OrderedDict[Hashable, type] = OrderedDict() |
| 28 | + |
| 29 | + def __contains__(self, key: Hashable) -> bool: |
| 30 | + try: |
| 31 | + self.get_class(key) |
| 32 | + except RegistryKeyError: |
| 33 | + return False |
| 34 | + return True |
| 35 | + |
| 36 | + def __getitem__(self, key: Hashable) -> object: |
| 37 | + return self.get(key) |
| 38 | + |
| 39 | + def __iter__(self) -> Iterator[Hashable]: |
| 40 | + return self.keys() |
| 41 | + |
| 42 | + def __len__(self) -> int: |
| 43 | + return len(self._registry) |
| 44 | + |
| 45 | + def __repr__(self) -> str: |
| 46 | + return f'{type(self).__name__}(attr_name={self.attr_name!r}, unique={self.unique!r})' |
| 47 | + |
| 48 | + def __setitem__(self, key: Hashable, class_: type) -> None: |
| 49 | + self._register(key, class_) |
| 50 | + |
| 51 | + def __delitem__(self, key: Hashable) -> None: |
| 52 | + self._unregister(key) |
| 53 | + |
| 54 | + def __missing__(self, key: Hashable) -> object: |
| 55 | + raise RegistryKeyError(key) |
| 56 | + |
| 57 | + @staticmethod |
| 58 | + def create_instance(class_: type, *args: Any, **kwargs: Any) -> object: |
| 59 | + return class_(*args, **kwargs) |
| 60 | + |
| 61 | + def get_class(self, key: Hashable) -> type: |
| 62 | + try: |
| 63 | + return self._registry[key] |
| 64 | + except KeyError: |
| 65 | + return self.__missing__(key) |
| 66 | + |
| 67 | + def get(self, key: Hashable, *args: Any, **kwargs: Any) -> object: |
| 68 | + return self.create_instance(self.get_class(key), *args, **kwargs) |
| 69 | + |
| 70 | + def items(self) -> Iterable[tuple[Hashable, type]]: |
| 71 | + return self._registry.items() |
| 72 | + |
| 73 | + def keys(self) -> Iterable[Hashable]: |
| 74 | + return self._registry.keys() |
| 75 | + |
| 76 | + def values(self) -> Iterable[type]: |
| 77 | + return self._registry.values() |
| 78 | + |
| 79 | + def register(self, key: Hashable | type) -> Callable[[type], type] | type: |
| 80 | + if isinstance(key, type): |
| 81 | + if not self.attr_name: |
| 82 | + raise ValueError( |
| 83 | + f'Attempting to register {key.__name__} via decorator, but attr_name is not set.' |
| 84 | + ) |
| 85 | + attr_key = getattr(key, self.attr_name) |
| 86 | + self._register(attr_key, key) |
| 87 | + return key |
| 88 | + |
| 89 | + def _decorator(cls: type) -> type: |
| 90 | + self._register(key, cls) |
| 91 | + return cls |
| 92 | + |
| 93 | + return _decorator |
| 94 | + |
| 95 | + def unregister(self, key: Hashable) -> type: |
| 96 | + return self._unregister(key) |
| 97 | + |
| 98 | + def _register(self, key: Hashable, class_: type) -> None: |
| 99 | + if key in ['', None]: |
| 100 | + raise ValueError( |
| 101 | + f'Attempting to register class {class_.__name__} with empty registry key {key!r}.' |
| 102 | + ) |
| 103 | + if self.unique and key in self._registry: |
| 104 | + raise RegistryKeyError(f'{class_.__name__} with key {key!r} is already registered.') |
| 105 | + self._registry[key] = class_ |
| 106 | + |
| 107 | + def _unregister(self, key: Hashable) -> type: |
| 108 | + return self._registry.pop(key) if key in self._registry else self.__missing__(key) |
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