109 lines
2.3 KiB
Python
109 lines
2.3 KiB
Python
from __future__ import annotations
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from abc import ABC, abstractmethod
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from typing import Any, Callable, Generic, Never, TypeVar
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S = TypeVar("S", covariant=True)
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S1 = TypeVar("S1")
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S2 = TypeVar("S2")
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S3 = TypeVar("S3")
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class Result(ABC, Generic[S]):
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@staticmethod
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def of(value: S1) -> Result[S1]:
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return Success(value)
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@staticmethod
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def fail(failure: str) -> Result[Any]:
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return Failure(failure)
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@abstractmethod
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def is_ok(self) -> bool:
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pass
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@abstractmethod
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def is_fail(self) -> bool:
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pass
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@abstractmethod
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def fmap(self, func: Callable[[S], S2]) -> Result[S2]:
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pass
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@abstractmethod
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def bind(self, func: Callable[[S], Result[S2]]) -> Result[S2]:
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pass
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@abstractmethod
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def get(self) -> S:
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pass
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@abstractmethod
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def get_or(self, default: S1) -> S | S1:
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pass
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@abstractmethod
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def get_or_else(self, default: Callable[[], S]) -> S:
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pass
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@abstractmethod
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def get_error(self) -> str:
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pass
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class Success(Result[S]):
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def __init__(self, value: S):
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self.value = value
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def is_ok(self) -> bool:
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return True
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def is_fail(self) -> bool:
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return False
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def fmap(self, func: Callable[[S], S2]) -> Result[S2]:
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return Result.of(func(self.value)) # type: ignore
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def bind(self, func: Callable[[S], Result[S2]]) -> Result[S2]:
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return func(self.value)
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def get(self) -> S:
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return self.value
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def get_or(self, default: S1) -> S | S1:
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return self.value
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def get_or_else(self, default: Callable[[], S]) -> S:
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return self.value
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def get_error(self) -> Never:
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raise Exception("No Error in Success Value")
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class Failure(Result[Any]):
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def __init__(self, value: str):
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self.value = value
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def is_ok(self) -> bool:
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return False
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def is_fail(self) -> bool:
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return True
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def fmap(self, func: Callable[[Any], S2]) -> Result[S2]:
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return self
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def bind(self, func: Callable[[Any], Result[S2]]) -> Result[S2]:
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return self
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def get(self) -> Never:
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raise Exception("No value in Fail")
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def get_or(self, default: S1) -> S1:
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return default
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def get_or_else(self, default: Callable[[], S]) -> S:
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return default()
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def get_error(self) -> str:
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return self.value
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