356 lines
10 KiB
Python
356 lines
10 KiB
Python
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# orm/identity.py
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# Copyright (C) 2005-2018 the SQLAlchemy authors and contributors
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# <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: http://www.opensource.org/licenses/mit-license.php
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import weakref
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from . import attributes
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from .. import util
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from .. import exc as sa_exc
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from . import util as orm_util
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class IdentityMap(object):
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def __init__(self):
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self._dict = {}
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self._modified = set()
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self._wr = weakref.ref(self)
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def keys(self):
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return self._dict.keys()
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def replace(self, state):
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raise NotImplementedError()
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def add(self, state):
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raise NotImplementedError()
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def _add_unpresent(self, state, key):
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"""optional inlined form of add() which can assume item isn't present
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in the map"""
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self.add(state)
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def update(self, dict):
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raise NotImplementedError("IdentityMap uses add() to insert data")
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def clear(self):
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raise NotImplementedError("IdentityMap uses remove() to remove data")
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def _manage_incoming_state(self, state):
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state._instance_dict = self._wr
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if state.modified:
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self._modified.add(state)
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def _manage_removed_state(self, state):
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del state._instance_dict
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if state.modified:
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self._modified.discard(state)
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def _dirty_states(self):
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return self._modified
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def check_modified(self):
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"""return True if any InstanceStates present have been marked
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as 'modified'.
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"""
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return bool(self._modified)
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def has_key(self, key):
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return key in self
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def popitem(self):
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raise NotImplementedError("IdentityMap uses remove() to remove data")
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def pop(self, key, *args):
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raise NotImplementedError("IdentityMap uses remove() to remove data")
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def setdefault(self, key, default=None):
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raise NotImplementedError("IdentityMap uses add() to insert data")
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def __len__(self):
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return len(self._dict)
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def copy(self):
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raise NotImplementedError()
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def __setitem__(self, key, value):
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raise NotImplementedError("IdentityMap uses add() to insert data")
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def __delitem__(self, key):
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raise NotImplementedError("IdentityMap uses remove() to remove data")
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class WeakInstanceDict(IdentityMap):
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def __getitem__(self, key):
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state = self._dict[key]
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o = state.obj()
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if o is None:
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raise KeyError(key)
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return o
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def __contains__(self, key):
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try:
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if key in self._dict:
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state = self._dict[key]
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o = state.obj()
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else:
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return False
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except KeyError:
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return False
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else:
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return o is not None
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def contains_state(self, state):
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if state.key in self._dict:
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try:
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return self._dict[state.key] is state
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except KeyError:
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return False
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else:
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return False
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def replace(self, state):
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if state.key in self._dict:
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try:
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existing = self._dict[state.key]
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except KeyError:
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# catch gc removed the key after we just checked for it
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pass
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else:
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if existing is not state:
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self._manage_removed_state(existing)
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else:
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return
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self._dict[state.key] = state
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self._manage_incoming_state(state)
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def add(self, state):
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key = state.key
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# inline of self.__contains__
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if key in self._dict:
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try:
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existing_state = self._dict[key]
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except KeyError:
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# catch gc removed the key after we just checked for it
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pass
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else:
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if existing_state is not state:
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o = existing_state.obj()
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if o is not None:
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raise sa_exc.InvalidRequestError(
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"Can't attach instance "
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"%s; another instance with key %s is already "
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"present in this session." % (
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orm_util.state_str(state), state.key))
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else:
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return False
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self._dict[key] = state
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self._manage_incoming_state(state)
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return True
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def _add_unpresent(self, state, key):
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# inlined form of add() called by loading.py
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self._dict[key] = state
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state._instance_dict = self._wr
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def get(self, key, default=None):
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if key not in self._dict:
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return default
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try:
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state = self._dict[key]
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except KeyError:
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# catch gc removed the key after we just checked for it
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return default
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else:
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o = state.obj()
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if o is None:
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return default
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return o
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def items(self):
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values = self.all_states()
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result = []
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for state in values:
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value = state.obj()
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if value is not None:
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result.append((state.key, value))
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return result
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def values(self):
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values = self.all_states()
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result = []
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for state in values:
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value = state.obj()
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if value is not None:
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result.append(value)
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return result
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def __iter__(self):
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return iter(self.keys())
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if util.py2k:
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def iteritems(self):
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return iter(self.items())
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def itervalues(self):
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return iter(self.values())
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def all_states(self):
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if util.py2k:
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return self._dict.values()
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else:
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return list(self._dict.values())
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def _fast_discard(self, state):
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# used by InstanceState for state being
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# GC'ed, inlines _managed_removed_state
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try:
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st = self._dict[state.key]
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except KeyError:
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# catch gc removed the key after we just checked for it
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pass
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else:
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if st is state:
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self._dict.pop(state.key, None)
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def discard(self, state):
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self.safe_discard(state)
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def safe_discard(self, state):
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if state.key in self._dict:
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try:
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st = self._dict[state.key]
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except KeyError:
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# catch gc removed the key after we just checked for it
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pass
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else:
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if st is state:
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self._dict.pop(state.key, None)
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self._manage_removed_state(state)
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def prune(self):
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return 0
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class StrongInstanceDict(IdentityMap):
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"""A 'strong-referencing' version of the identity map.
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.. deprecated 1.1::
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The strong
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reference identity map is legacy. See the
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recipe at :ref:`session_referencing_behavior` for
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an event-based approach to maintaining strong identity
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references.
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"""
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if util.py2k:
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def itervalues(self):
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return self._dict.itervalues()
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def iteritems(self):
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return self._dict.iteritems()
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def __iter__(self):
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return iter(self.dict_)
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def __getitem__(self, key):
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return self._dict[key]
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def __contains__(self, key):
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return key in self._dict
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def get(self, key, default=None):
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return self._dict.get(key, default)
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def values(self):
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return self._dict.values()
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def items(self):
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return self._dict.items()
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def all_states(self):
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return [attributes.instance_state(o) for o in self.values()]
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def contains_state(self, state):
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return (
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state.key in self and
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attributes.instance_state(self[state.key]) is state)
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def replace(self, state):
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if state.key in self._dict:
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existing = self._dict[state.key]
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existing = attributes.instance_state(existing)
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if existing is not state:
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self._manage_removed_state(existing)
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else:
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return
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self._dict[state.key] = state.obj()
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self._manage_incoming_state(state)
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def add(self, state):
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if state.key in self:
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if attributes.instance_state(self._dict[state.key]) is not state:
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raise sa_exc.InvalidRequestError(
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"Can't attach instance "
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"%s; another instance with key %s is already "
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"present in this session." % (
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orm_util.state_str(state), state.key))
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return False
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else:
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self._dict[state.key] = state.obj()
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self._manage_incoming_state(state)
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return True
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def _add_unpresent(self, state, key):
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# inlined form of add() called by loading.py
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self._dict[key] = state.obj()
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state._instance_dict = self._wr
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def _fast_discard(self, state):
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# used by InstanceState for state being
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# GC'ed, inlines _managed_removed_state
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try:
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obj = self._dict[state.key]
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except KeyError:
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# catch gc removed the key after we just checked for it
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pass
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else:
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if attributes.instance_state(obj) is state:
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self._dict.pop(state.key, None)
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def discard(self, state):
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self.safe_discard(state)
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def safe_discard(self, state):
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if state.key in self._dict:
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obj = self._dict[state.key]
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st = attributes.instance_state(obj)
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if st is state:
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self._dict.pop(state.key, None)
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self._manage_removed_state(state)
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def prune(self):
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"""prune unreferenced, non-dirty states."""
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ref_count = len(self)
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dirty = [s.obj() for s in self.all_states() if s.modified]
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# work around http://bugs.python.org/issue6149
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keepers = weakref.WeakValueDictionary()
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keepers.update(self)
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self._dict.clear()
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self._dict.update(keepers)
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self.modified = bool(dirty)
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return ref_count - len(self)
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