# orm/identity.py
# Copyright (C) 2005-2025 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: https://www.opensource.org/licenses/mit-license.php
from __future__ import annotations
from typing import Any
from typing import cast
from typing import Dict
from typing import Iterable
from typing import Iterator
from typing import List
from typing import NoReturn
from typing import Optional
from typing import Set
from typing import Tuple
from typing import TYPE_CHECKING
from typing import TypeVar
import weakref
from . import util as orm_util
from .. import exc as sa_exc
if TYPE_CHECKING:
from ._typing import _IdentityKeyType
from .state import InstanceState
_T = TypeVar("_T", bound=Any)
_O = TypeVar("_O", bound=object)
class IdentityMap:
_wr: weakref.ref[IdentityMap]
_dict: Dict[_IdentityKeyType[Any], Any]
_modified: Set[InstanceState[Any]]
def __init__(self) -> None:
self._dict = {}
self._modified = set()
self._wr = weakref.ref(self)
def _kill(self) -> None:
self._add_unpresent = _killed # type: ignore
def all_states(self) -> List[InstanceState[Any]]:
raise NotImplementedError()
def contains_state(self, state: InstanceState[Any]) -> bool:
raise NotImplementedError()
def __contains__(self, key: _IdentityKeyType[Any]) -> bool:
raise NotImplementedError()
def safe_discard(self, state: InstanceState[Any]) -> None:
raise NotImplementedError()
def __getitem__(self, key: _IdentityKeyType[_O]) -> _O:
raise NotImplementedError()
def get(
self, key: _IdentityKeyType[_O], default: Optional[_O] = None
) -> Optional[_O]:
raise NotImplementedError()
def fast_get_state(
self, key: _IdentityKeyType[_O]
) -> Optional[InstanceState[_O]]:
raise NotImplementedError()
def keys(self) -> Iterable[_IdentityKeyType[Any]]:
return self._dict.keys()
def values(self) -> Iterable[object]:
raise NotImplementedError()
def replace(self, state: InstanceState[_O]) -> Optional[InstanceState[_O]]:
raise NotImplementedError()
def add(self, state: InstanceState[Any]) -> bool:
raise NotImplementedError()
def _fast_discard(self, state: InstanceState[Any]) -> None:
raise NotImplementedError()
def _add_unpresent(
self, state: InstanceState[Any], key: _IdentityKeyType[Any]
) -> None:
"""optional inlined form of add() which can assume item isn't present
in the map"""
self.add(state)
def _manage_incoming_state(self, state: InstanceState[Any]) -> None:
state._instance_dict = self._wr
if state.modified:
self._modified.add(state)
def _manage_removed_state(self, state: InstanceState[Any]) -> None:
del state._instance_dict
if state.modified:
self._modified.discard(state)
def _dirty_states(self) -> Set[InstanceState[Any]]:
return self._modified
def check_modified(self) -> bool:
"""return True if any InstanceStates present have been marked
as 'modified'.
"""
return bool(self._modified)
def has_key(self, key: _IdentityKeyType[Any]) -> bool:
return key in self
def __len__(self) -> int:
return len(self._dict)
class WeakInstanceDict(IdentityMap):
_dict: Dict[_IdentityKeyType[Any], InstanceState[Any]]
def __getitem__(self, key: _IdentityKeyType[_O]) -> _O:
state = cast("InstanceState[_O]", self._dict[key])
o = state.obj()
if o is None:
raise KeyError(key)
return o
def __contains__(self, key: _IdentityKeyType[Any]) -> bool:
try:
if key in self._dict:
state = self._dict[key]
o = state.obj()
else:
return False
except KeyError:
return False
else:
return o is not None
def contains_state(self, state: InstanceState[Any]) -> bool:
if state.key in self._dict:
if TYPE_CHECKING:
assert state.key is not None
try:
return self._dict[state.key] is state
except KeyError:
return False
else:
return False
def replace(
self, state: InstanceState[Any]
) -> Optional[InstanceState[Any]]:
assert state.key is not None
if state.key in self._dict:
try:
existing = existing_non_none = self._dict[state.key]
except KeyError:
# catch gc removed the key after we just checked for it
existing = None
else:
if existing_non_none is not state:
self._manage_removed_state(existing_non_none)
else:
return None
else:
existing = None
self._dict[state.key] = state
self._manage_incoming_state(state)
return existing
def add(self, state: InstanceState[Any]) -> bool:
key = state.key
assert key is not None
# inline of self.__contains__
if key in self._dict:
try:
existing_state = self._dict[key]
except KeyError:
# catch gc removed the key after we just checked for it
pass
else:
if existing_state is not state:
o = existing_state.obj()
if o is not None:
raise sa_exc.InvalidRequestError(
"Can't attach instance "
"%s; another instance with key %s is already "
"present in this session."
% (orm_util.state_str(state), state.key)
)
else:
return False
self._dict[key] = state
self._manage_incoming_state(state)
return True
def _add_unpresent(
self, state: InstanceState[Any], key: _IdentityKeyType[Any]
) -> None:
# inlined form of add() called by loading.py
self._dict[key] = state
state._instance_dict = self._wr
def fast_get_state(
self, key: _IdentityKeyType[_O]
) -> Optional[InstanceState[_O]]:
return self._dict.get(key)
def get(
self, key: _IdentityKeyType[_O], default: Optional[_O] = None
) -> Optional[_O]:
if key not in self._dict:
return default
try:
state = cast("InstanceState[_O]", self._dict[key])
except KeyError:
# catch gc removed the key after we just checked for it
return default
else:
o = state.obj()
if o is None:
return default
return o
def items(self) -> List[Tuple[_IdentityKeyType[Any], InstanceState[Any]]]:
values = self.all_states()
result = []
for state in values:
value = state.obj()
key = state.key
assert key is not None
if value is not None:
result.append((key, value))
return result
def values(self) -> List[object]:
values = self.all_states()
result = []
for state in values:
value = state.obj()
if value is not None:
result.append(value)
return result
def __iter__(self) -> Iterator[_IdentityKeyType[Any]]:
return iter(self.keys())
def all_states(self) -> List[InstanceState[Any]]:
return list(self._dict.values())
def _fast_discard(self, state: InstanceState[Any]) -> None:
# used by InstanceState for state being
# GC'ed, inlines _managed_removed_state
key = state.key
assert key is not None
try:
st = self._dict[key]
except KeyError:
# catch gc removed the key after we just checked for it
pass
else:
if st is state:
self._dict.pop(key, None)
def discard(self, state: InstanceState[Any]) -> None:
self.safe_discard(state)
def safe_discard(self, state: InstanceState[Any]) -> None:
key = state.key
if key in self._dict:
assert key is not None
try:
st = self._dict[key]
except KeyError:
# catch gc removed the key after we just checked for it
pass
else:
if st is state:
self._dict.pop(key, None)
self._manage_removed_state(state)
def _killed(state: InstanceState[Any], key: _IdentityKeyType[Any]) -> NoReturn:
# external function to avoid creating cycles when assigned to
# the IdentityMap
raise sa_exc.InvalidRequestError(
"Object %s cannot be converted to 'persistent' state, as this "
"identity map is no longer valid. Has the owning Session "
"been closed?" % orm_util.state_str(state),
code="lkrp",
)
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