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from __future__ import annotations
from copy import copy, deepcopy
from threading import RLock
from typing import TYPE_CHECKING, Any, Callable, Generator, Iterable, Iterator, Mapping, MutableMapping
if TYPE_CHECKING:
from typing_extensions import Self
__all__ = ("ImmutableState", "State")
class ImmutableState(Mapping[str, Any]):
"""An object meant to store arbitrary state.
It can be accessed using dot notation while exposing dict like functionalities.
"""
__slots__ = (
"_state",
"_deep_copy",
)
_state: dict[str, Any]
def __init__(
self, state: ImmutableState | Mapping[str, Any] | Iterable[tuple[str, Any]], deep_copy: bool = True
) -> None:
"""Initialize an ``ImmutableState`` instance.
Args:
state: An object to initialize the state from. Can be a dict, an instance of :class:`ImmutableState`, or a tuple
of key value paris.
deep_copy: Whether to 'deepcopy' the passed in state.
Examples:
.. code-block:: python
from litestar.datastructures import ImmutableState
state_dict = {"first": 1, "second": 2, "third": 3, "fourth": 4}
state = ImmutableState(state_dict)
# state implements the Mapping type:
assert len(state) == 3
assert "first" in state
assert not "fourth" in state
assert state["first"] == 1
assert [(k, v) for k, v in state.items()] == [("first", 1), ("second", 2), ("third", 3)]
# state implements __bool__
assert state # state is true when it has values.
assert not State() # state is empty when it has no values.
# it has a 'dict' method to retrieve a shallow copy of the underlying dict
inner_dict = state.dict()
assert inner_dict == state_dict
# you can also retrieve a mutable State by calling 'mutable_copy'
mutable_state = state.mutable_copy()
del state["first"]
assert "first" not in state
"""
if isinstance(state, ImmutableState):
state = state._state
if not isinstance(state, dict) and isinstance(state, Iterable):
state = dict(state)
super().__setattr__("_deep_copy", deep_copy)
super().__setattr__("_state", deepcopy(state) if deep_copy else state)
def __bool__(self) -> bool:
"""Return a boolean indicating whether the wrapped dict instance has values."""
return bool(self._state)
def __getitem__(self, key: str) -> Any:
"""Get the value for the corresponding key from the wrapped state object using subscription notation.
Args:
key: Key to access.
Raises:
KeyError
Returns:
A value from the wrapped state instance.
"""
return self._state[key]
def __iter__(self) -> Iterator[str]:
"""Return an iterator iterating the wrapped state dict.
Returns:
An iterator of strings
"""
return iter(self._state)
def __len__(self) -> int:
"""Return length of the wrapped state dict.
Returns:
An integer
"""
return len(self._state)
def __getattr__(self, key: str) -> Any:
"""Get the value for the corresponding key from the wrapped state object using attribute notation.
Args:
key: Key to retrieve
Raises:
AttributeError: if the given attribute is not set.
Returns:
The retrieved value
"""
try:
return self._state[key]
except KeyError as e:
raise AttributeError from e
def __copy__(self) -> Self:
"""Return a shallow copy of the given state object.
Customizes how the builtin "copy" function will work.
"""
return self.__class__(self._state, deep_copy=self._deep_copy) # pyright: ignore
def mutable_copy(self) -> State:
"""Return a mutable copy of the state object.
Returns:
A ``State``
"""
return State(self._state, deep_copy=self._deep_copy)
def dict(self) -> dict[str, Any]:
"""Return a shallow copy of the wrapped dict.
Returns:
A dict
"""
return copy(self._state)
@classmethod
def __get_validators__(
cls,
) -> Generator[Callable[[ImmutableState | dict[str, Any] | Iterable[tuple[str, Any]]], ImmutableState], None, None]: # type: ignore[valid-type]
"""Pydantic compatible method to allow custom parsing of state instances in a SignatureModel."""
yield cls.validate
@classmethod
def validate(cls, value: ImmutableState | dict[str, Any] | Iterable[tuple[str, Any]]) -> Self: # type: ignore[valid-type]
"""Parse a value and instantiate state inside a SignatureModel. This allows us to use custom subclasses of
state, as well as allows users to decide whether state is mutable or immutable.
Args:
value: The value from which to initialize the state instance.
Returns:
An ImmutableState instance
"""
deep_copy = value._deep_copy if isinstance(value, ImmutableState) else False
return cls(value, deep_copy=deep_copy)
class State(ImmutableState, MutableMapping[str, Any]):
"""An object meant to store arbitrary state.
It can be accessed using dot notation while exposing dict like functionalities.
"""
__slots__ = ("_lock",)
_lock: RLock
def __init__(
self,
state: ImmutableState | Mapping[str, Any] | Iterable[tuple[str, Any]] | None = None,
deep_copy: bool = False,
) -> None:
"""Initialize a ``State`` instance with an optional value.
Args:
state: An object to initialize the state from. Can be a dict, an instance of 'ImmutableState', or a tuple of key value paris.
deep_copy: Whether to 'deepcopy' the passed in state.
.. code-block:: python
:caption: Examples
from litestar.datastructures import State
state_dict = {"first": 1, "second": 2, "third": 3, "fourth": 4}
state = State(state_dict)
# state can be accessed using '.' notation
assert state.fourth == 4
del state.fourth
# state implements the Mapping type:
assert len(state) == 3
assert "first" in state
assert not "fourth" in state
assert state["first"] == 1
assert [(k, v) for k, v in state.items()] == [("first", 1), ("second", 2), ("third", 3)]
state["fourth"] = 4
assert "fourth" in state
del state["fourth"]
# state implements __bool__
assert state # state is true when it has values.
assert not State() # state is empty when it has no values.
# it has shallow copy
copied_state = state.copy()
del copied_state.first
assert state.first
# it has a 'dict' method to retrieve a shallow copy of the underlying dict
inner_dict = state.dict()
assert inner_dict == state_dict
# you can get an immutable copy of the state by calling 'immutable_immutable_copy'
immutable_copy = state.immutable_copy()
del immutable_copy.first # raises AttributeError
"""
super().__init__(state if state is not None else {}, deep_copy=deep_copy)
super().__setattr__("_lock", RLock())
def __delitem__(self, key: str) -> None:
"""Delete the value from the key from the wrapped state object using subscription notation.
Args:
key: Key to delete
Raises:
KeyError: if the given attribute is not set.
Returns:
None
"""
with self._lock:
del self._state[key]
def __setitem__(self, key: str, value: Any) -> None:
"""Set an item in the state using subscription notation.
Args:
key: Key to set.
value: Value to set.
Returns:
None
"""
with self._lock:
self._state[key] = value
def __setattr__(self, key: str, value: Any) -> None:
"""Set an item in the state using attribute notation.
Args:
key: Key to set.
value: Value to set.
Returns:
None
"""
with self._lock:
self._state[key] = value
def __delattr__(self, key: str) -> None:
"""Delete the value from the key from the wrapped state object using attribute notation.
Args:
key: Key to delete
Raises:
AttributeError: if the given attribute is not set.
Returns:
None
"""
try:
with self._lock:
del self._state[key]
except KeyError as e:
raise AttributeError from e
def copy(self) -> Self:
"""Return a shallow copy of the state object.
Returns:
A ``State``
"""
return self.__class__(self.dict(), deep_copy=self._deep_copy) # pyright: ignore
def immutable_copy(self) -> ImmutableState:
"""Return a shallow copy of the state object, setting it to be frozen.
Returns:
A ``State``
"""
return ImmutableState(self, deep_copy=self._deep_copy)
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