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import functools |
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import inspect |
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from typing import Union, Type, Optional, Callable, TypeVar, Any |
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from .exceptions import InvalidDependencyDefinition |
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from .interfaces import SpecialDepDefinition |
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from .util.functional import arity |
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X = TypeVar("X") |
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class Construction(SpecialDepDefinition[X]): |
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constructor: Callable[[], X] |
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def __init__(self, constructor): |
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self.constructor = constructor |
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def get_instance(self, _build_func) -> X: |
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call = self.constructor # type: ignore |
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return call() |
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class Alias(SpecialDepDefinition[X]): |
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alias_type: Type[X] |
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def __init__(self, alias_type): |
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self.alias_type = alias_type |
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def get_instance(self, build_func) -> X: |
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return build_func(self.alias_type) |
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class Singleton(SpecialDepDefinition[X]): |
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singleton_type: Union[Type[X], Construction[X]] |
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_instance: Optional[X] |
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def __init__(self, singleton_type: Union[Type[X], Construction[X]]): |
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self.singleton_type = singleton_type |
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self._instance = None |
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def get_instance(self, build_func) -> X: |
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if self._has_instance: |
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return self._instance # type: ignore |
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return self._set_instance(build_func(self.singleton_type)) |
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@property |
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def _has_instance(self): |
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return self._instance is not None |
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def _set_instance(self, instance: X): |
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self._instance = instance |
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return instance |
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def normalise(resolver: Any, container) -> SpecialDepDefinition: |
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if isinstance(resolver, SpecialDepDefinition): |
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return resolver |
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elif inspect.isfunction(resolver): |
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return _build_lambda_constructor(resolver, container) |
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elif not inspect.isclass(resolver): |
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return Singleton(lambda: resolver) # type: ignore |
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else: |
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return Alias(resolver) |
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def _build_lambda_constructor(resolver: Callable, container) -> Construction: |
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artiy = arity(resolver) |
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if artiy == 0: |
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return Construction(resolver) |
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if artiy == 1: |
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return Construction(functools.partial(resolver, container)) |
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raise InvalidDependencyDefinition(f"Arity {arity} functions are not supported") |
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meadsteve /
lagom
