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ahriman/src/ahriman/core/__init__.py

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3.0 KiB
Python

#
# Copyright (c) 2021-2024 ahriman team.
#
# This file is part of ahriman
# (see https://github.com/arcan1s/ahriman).
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
from collections.abc import Iterator
from contextvars import ContextVar
from typing import Any, TypeVar
from ahriman.models.context_key import ContextKey
T = TypeVar("T")
class _Context:
"""
simple ahriman global context implementation
"""
def __init__(self) -> None:
"""
default constructor. Must not be used directly
"""
self._content: dict[str, Any] = {}
def get(self, key: ContextKey[T]) -> T:
"""
get value for the specified key
Args:
key(ContextKey[T]): context key name
Returns:
T: value associated with the key
Raises:
KeyError: in case if the specified context variable was not found
ValueError: in case if type of value is not an instance of specified return type
"""
if key.key not in self._content:
raise KeyError(key.key)
value = self._content[key.key]
if not isinstance(value, key.return_type):
raise ValueError(f"Value {value} is not an instance of {key.return_type}")
return value
def set(self, key: ContextKey[T], value: T) -> None:
"""
set value for the specified key
Args:
key(ContextKey[T]): context key name
value(T): context value associated with the specified key
Raises:
KeyError: in case if the specified context variable already exists
ValueError: in case if type of value is not an instance of specified return type
"""
if key.key in self._content:
raise KeyError(key.key)
if not isinstance(value, key.return_type):
raise ValueError(f"Value {value} is not an instance of {key.return_type}")
self._content[key.key] = value
def __iter__(self) -> Iterator[str]:
"""
iterate over keys in local storage
Returns:
str: context key iterator
"""
return iter(self._content)
def __len__(self) -> int:
"""
get count of the context variables set
Returns:
int: count of stored context variables
"""
return len(self._content)
context = ContextVar("context", default=_Context())