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Edit File: associationproxy.py
# ext/associationproxy.py # Copyright (C) 2005-2023 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 """Contain the ``AssociationProxy`` class. The ``AssociationProxy`` is a Python property object which provides transparent proxied access to the endpoint of an association object. See the example ``examples/association/proxied_association.py``. """ import operator from .. import exc from .. import inspect from .. import orm from .. import util from ..orm import collections from ..orm import interfaces from ..sql import or_ from ..sql.operators import ColumnOperators def association_proxy(target_collection, attr, **kw): r"""Return a Python property implementing a view of a target attribute which references an attribute on members of the target. The returned value is an instance of :class:`.AssociationProxy`. Implements a Python property representing a relationship as a collection of simpler values, or a scalar value. The proxied property will mimic the collection type of the target (list, dict or set), or, in the case of a one to one relationship, a simple scalar value. :param target_collection: Name of the attribute we'll proxy to. This attribute is typically mapped by :func:`~sqlalchemy.orm.relationship` to link to a target collection, but can also be a many-to-one or non-scalar relationship. :param attr: Attribute on the associated instance or instances we'll proxy for. For example, given a target collection of [obj1, obj2], a list created by this proxy property would look like [getattr(obj1, *attr*), getattr(obj2, *attr*)] If the relationship is one-to-one or otherwise uselist=False, then simply: getattr(obj, *attr*) :param creator: optional. When new items are added to this proxied collection, new instances of the class collected by the target collection will be created. For list and set collections, the target class constructor will be called with the 'value' for the new instance. For dict types, two arguments are passed: key and value. If you want to construct instances differently, supply a *creator* function that takes arguments as above and returns instances. For scalar relationships, creator() will be called if the target is None. If the target is present, set operations are proxied to setattr() on the associated object. If you have an associated object with multiple attributes, you may set up multiple association proxies mapping to different attributes. See the unit tests for examples, and for examples of how creator() functions can be used to construct the scalar relationship on-demand in this situation. :param \*\*kw: Passes along any other keyword arguments to :class:`.AssociationProxy`. """ return AssociationProxy(target_collection, attr, **kw) ASSOCIATION_PROXY = util.symbol("ASSOCIATION_PROXY") """Symbol indicating an :class:`.InspectionAttr` that's of type :class:`.AssociationProxy`. Is assigned to the :attr:`.InspectionAttr.extension_type` attribute. """ class AssociationProxy(interfaces.InspectionAttrInfo): """A descriptor that presents a read/write view of an object attribute.""" is_attribute = True extension_type = ASSOCIATION_PROXY def __init__( self, target_collection, attr, creator=None, getset_factory=None, proxy_factory=None, proxy_bulk_set=None, info=None, cascade_scalar_deletes=False, ): """Construct a new :class:`.AssociationProxy`. The :func:`.association_proxy` function is provided as the usual entrypoint here, though :class:`.AssociationProxy` can be instantiated and/or subclassed directly. :param target_collection: Name of the collection we'll proxy to, usually created with :func:`_orm.relationship`. :param attr: Attribute on the collected instances we'll proxy for. For example, given a target collection of [obj1, obj2], a list created by this proxy property would look like [getattr(obj1, attr), getattr(obj2, attr)] :param creator: Optional. When new items are added to this proxied collection, new instances of the class collected by the target collection will be created. For list and set collections, the target class constructor will be called with the 'value' for the new instance. For dict types, two arguments are passed: key and value. If you want to construct instances differently, supply a 'creator' function that takes arguments as above and returns instances. :param cascade_scalar_deletes: when True, indicates that setting the proxied value to ``None``, or deleting it via ``del``, should also remove the source object. Only applies to scalar attributes. Normally, removing the proxied target will not remove the proxy source, as this object may have other state that is still to be kept. .. versionadded:: 1.3 .. seealso:: :ref:`cascade_scalar_deletes` - complete usage example :param getset_factory: Optional. Proxied attribute access is automatically handled by routines that get and set values based on the `attr` argument for this proxy. If you would like to customize this behavior, you may supply a `getset_factory` callable that produces a tuple of `getter` and `setter` functions. The factory is called with two arguments, the abstract type of the underlying collection and this proxy instance. :param proxy_factory: Optional. The type of collection to emulate is determined by sniffing the target collection. If your collection type can't be determined by duck typing or you'd like to use a different collection implementation, you may supply a factory function to produce those collections. Only applicable to non-scalar relationships. :param proxy_bulk_set: Optional, use with proxy_factory. See the _set() method for details. :param info: optional, will be assigned to :attr:`.AssociationProxy.info` if present. .. versionadded:: 1.0.9 """ self.target_collection = target_collection self.value_attr = attr self.creator = creator self.getset_factory = getset_factory self.proxy_factory = proxy_factory self.proxy_bulk_set = proxy_bulk_set self.cascade_scalar_deletes = cascade_scalar_deletes self.key = "_%s_%s_%s" % ( type(self).__name__, target_collection, id(self), ) if info: self.info = info def __get__(self, obj, class_): if class_ is None: return self inst = self._as_instance(class_, obj) if inst: return inst.get(obj) # obj has to be None here # assert obj is None return self def __set__(self, obj, values): class_ = type(obj) return self._as_instance(class_, obj).set(obj, values) def __delete__(self, obj): class_ = type(obj) return self._as_instance(class_, obj).delete(obj) def for_class(self, class_, obj=None): r"""Return the internal state local to a specific mapped class. E.g., given a class ``User``:: class User(Base): # ... keywords = association_proxy('kws', 'keyword') If we access this :class:`.AssociationProxy` from :attr:`_orm.Mapper.all_orm_descriptors`, and we want to view the target class for this proxy as mapped by ``User``:: inspect(User).all_orm_descriptors["keywords"].for_class(User).target_class This returns an instance of :class:`.AssociationProxyInstance` that is specific to the ``User`` class. The :class:`.AssociationProxy` object remains agnostic of its parent class. :param class\_: the class that we are returning state for. :param obj: optional, an instance of the class that is required if the attribute refers to a polymorphic target, e.g. where we have to look at the type of the actual destination object to get the complete path. .. versionadded:: 1.3 - :class:`.AssociationProxy` no longer stores any state specific to a particular parent class; the state is now stored in per-class :class:`.AssociationProxyInstance` objects. """ return self._as_instance(class_, obj) def _as_instance(self, class_, obj): try: inst = class_.__dict__[self.key + "_inst"] except KeyError: inst = None # avoid exception context if inst is None: owner = self._calc_owner(class_) if owner is not None: inst = AssociationProxyInstance.for_proxy(self, owner, obj) setattr(class_, self.key + "_inst", inst) else: inst = None if inst is not None and not inst._is_canonical: # the AssociationProxyInstance can't be generalized # since the proxied attribute is not on the targeted # class, only on subclasses of it, which might be # different. only return for the specific # object's current value return inst._non_canonical_get_for_object(obj) else: return inst def _calc_owner(self, target_cls): # we might be getting invoked for a subclass # that is not mapped yet, in some declarative situations. # save until we are mapped try: insp = inspect(target_cls) except exc.NoInspectionAvailable: # can't find a mapper, don't set owner. if we are a not-yet-mapped # subclass, we can also scan through __mro__ to find a mapped # class, but instead just wait for us to be called again against a # mapped class normally. return None else: return insp.mapper.class_manager.class_ def _default_getset(self, collection_class): attr = self.value_attr _getter = operator.attrgetter(attr) def getter(target): return _getter(target) if target is not None else None if collection_class is dict: def setter(o, k, v): setattr(o, attr, v) else: def setter(o, v): setattr(o, attr, v) return getter, setter def __repr__(self): return "AssociationProxy(%r, %r)" % ( self.target_collection, self.value_attr, ) class AssociationProxyInstance(object): """A per-class object that serves class- and object-specific results. This is used by :class:`.AssociationProxy` when it is invoked in terms of a specific class or instance of a class, i.e. when it is used as a regular Python descriptor. When referring to the :class:`.AssociationProxy` as a normal Python descriptor, the :class:`.AssociationProxyInstance` is the object that actually serves the information. Under normal circumstances, its presence is transparent:: >>> User.keywords.scalar False In the special case that the :class:`.AssociationProxy` object is being accessed directly, in order to get an explicit handle to the :class:`.AssociationProxyInstance`, use the :meth:`.AssociationProxy.for_class` method:: proxy_state = inspect(User).all_orm_descriptors["keywords"].for_class(User) # view if proxy object is scalar or not >>> proxy_state.scalar False .. versionadded:: 1.3 """ # noqa def __init__(self, parent, owning_class, target_class, value_attr): self.parent = parent self.key = parent.key self.owning_class = owning_class self.target_collection = parent.target_collection self.collection_class = None self.target_class = target_class self.value_attr = value_attr target_class = None """The intermediary class handled by this :class:`.AssociationProxyInstance`. Intercepted append/set/assignment events will result in the generation of new instances of this class. """ @classmethod def for_proxy(cls, parent, owning_class, parent_instance): target_collection = parent.target_collection value_attr = parent.value_attr prop = orm.class_mapper(owning_class).get_property(target_collection) # this was never asserted before but this should be made clear. if not isinstance(prop, orm.RelationshipProperty): util.raise_( NotImplementedError( "association proxy to a non-relationship " "intermediary is not supported" ), replace_context=None, ) target_class = prop.mapper.class_ try: target_assoc = cls._cls_unwrap_target_assoc_proxy( target_class, value_attr ) except AttributeError: # the proxied attribute doesn't exist on the target class; # return an "ambiguous" instance that will work on a per-object # basis return AmbiguousAssociationProxyInstance( parent, owning_class, target_class, value_attr ) except Exception as err: util.raise_( exc.InvalidRequestError( "Association proxy received an unexpected error when " "trying to retreive attribute " '"%s.%s" from ' 'class "%s": %s' % ( target_class.__name__, parent.value_attr, target_class.__name__, err, ) ), from_=err, ) else: return cls._construct_for_assoc( target_assoc, parent, owning_class, target_class, value_attr ) @classmethod def _construct_for_assoc( cls, target_assoc, parent, owning_class, target_class, value_attr ): if target_assoc is not None: return ObjectAssociationProxyInstance( parent, owning_class, target_class, value_attr ) attr = getattr(target_class, value_attr) if not hasattr(attr, "_is_internal_proxy"): return AmbiguousAssociationProxyInstance( parent, owning_class, target_class, value_attr ) is_object = attr._impl_uses_objects if is_object: return ObjectAssociationProxyInstance( parent, owning_class, target_class, value_attr ) else: return ColumnAssociationProxyInstance( parent, owning_class, target_class, value_attr ) def _get_property(self): return orm.class_mapper(self.owning_class).get_property( self.target_collection ) @property def _comparator(self): return self._get_property().comparator def __clause_element__(self): raise NotImplementedError( "The association proxy can't be used as a plain column " "expression; it only works inside of a comparison expression" ) @classmethod def _cls_unwrap_target_assoc_proxy(cls, target_class, value_attr): attr = getattr(target_class, value_attr) if isinstance(attr, (AssociationProxy, AssociationProxyInstance)): return attr return None @util.memoized_property def _unwrap_target_assoc_proxy(self): return self._cls_unwrap_target_assoc_proxy( self.target_class, self.value_attr ) @property def remote_attr(self): """The 'remote' class attribute referenced by this :class:`.AssociationProxyInstance`. .. seealso:: :attr:`.AssociationProxyInstance.attr` :attr:`.AssociationProxyInstance.local_attr` """ return getattr(self.target_class, self.value_attr) @property def local_attr(self): """The 'local' class attribute referenced by this :class:`.AssociationProxyInstance`. .. seealso:: :attr:`.AssociationProxyInstance.attr` :attr:`.AssociationProxyInstance.remote_attr` """ return getattr(self.owning_class, self.target_collection) @property def attr(self): """Return a tuple of ``(local_attr, remote_attr)``. This attribute was originally intended to facilitate using the :meth:`_query.Query.join` method to join across the two relationships at once, however this makes use of a deprecated calling style. To use :meth:`_sql.select.join` or :meth:`_orm.Query.join` with an association proxy, the current method is to make use of the :attr:`.AssociationProxyInstance.local_attr` and :attr:`.AssociationProxyInstance.remote_attr` attributes separately:: stmt = ( select(Parent). join(Parent.proxied.local_attr). join(Parent.proxied.remote_attr) ) A future release may seek to provide a more succinct join pattern for association proxy attributes. .. seealso:: :attr:`.AssociationProxyInstance.local_attr` :attr:`.AssociationProxyInstance.remote_attr` """ return (self.local_attr, self.remote_attr) @util.memoized_property def scalar(self): """Return ``True`` if this :class:`.AssociationProxyInstance` proxies a scalar relationship on the local side.""" scalar = not self._get_property().uselist if scalar: self._initialize_scalar_accessors() return scalar @util.memoized_property def _value_is_scalar(self): return ( not self._get_property() .mapper.get_property(self.value_attr) .uselist ) @property def _target_is_object(self): raise NotImplementedError() def _initialize_scalar_accessors(self): if self.parent.getset_factory: get, set_ = self.parent.getset_factory(None, self) else: get, set_ = self.parent._default_getset(None) self._scalar_get, self._scalar_set = get, set_ def _default_getset(self, collection_class): attr = self.value_attr _getter = operator.attrgetter(attr) def getter(target): return _getter(target) if target is not None else None if collection_class is dict: def setter(o, k, v): return setattr(o, attr, v) else: def setter(o, v): return setattr(o, attr, v) return getter, setter @property def info(self): return self.parent.info def get(self, obj): if obj is None: return self if self.scalar: target = getattr(obj, self.target_collection) return self._scalar_get(target) else: try: # If the owning instance is reborn (orm session resurrect, # etc.), refresh the proxy cache. creator_id, self_id, proxy = getattr(obj, self.key) except AttributeError: pass else: if id(obj) == creator_id and id(self) == self_id: assert self.collection_class is not None return proxy self.collection_class, proxy = self._new( _lazy_collection(obj, self.target_collection) ) setattr(obj, self.key, (id(obj), id(self), proxy)) return proxy def set(self, obj, values): if self.scalar: creator = ( self.parent.creator if self.parent.creator else self.target_class ) target = getattr(obj, self.target_collection) if target is None: if values is None: return setattr(obj, self.target_collection, creator(values)) else: self._scalar_set(target, values) if values is None and self.parent.cascade_scalar_deletes: setattr(obj, self.target_collection, None) else: proxy = self.get(obj) assert self.collection_class is not None if proxy is not values: proxy._bulk_replace(self, values) def delete(self, obj): if self.owning_class is None: self._calc_owner(obj, None) if self.scalar: target = getattr(obj, self.target_collection) if target is not None: delattr(target, self.value_attr) delattr(obj, self.target_collection) def _new(self, lazy_collection): creator = ( self.parent.creator if self.parent.creator else self.target_class ) collection_class = util.duck_type_collection(lazy_collection()) if self.parent.proxy_factory: return ( collection_class, self.parent.proxy_factory( lazy_collection, creator, self.value_attr, self ), ) if self.parent.getset_factory: getter, setter = self.parent.getset_factory(collection_class, self) else: getter, setter = self.parent._default_getset(collection_class) if collection_class is list: return ( collection_class, _AssociationList( lazy_collection, creator, getter, setter, self ), ) elif collection_class is dict: return ( collection_class, _AssociationDict( lazy_collection, creator, getter, setter, self ), ) elif collection_class is set: return ( collection_class, _AssociationSet( lazy_collection, creator, getter, setter, self ), ) else: raise exc.ArgumentError( "could not guess which interface to use for " 'collection_class "%s" backing "%s"; specify a ' "proxy_factory and proxy_bulk_set manually" % (self.collection_class.__name__, self.target_collection) ) def _set(self, proxy, values): if self.parent.proxy_bulk_set: self.parent.proxy_bulk_set(proxy, values) elif self.collection_class is list: proxy.extend(values) elif self.collection_class is dict: proxy.update(values) elif self.collection_class is set: proxy.update(values) else: raise exc.ArgumentError( "no proxy_bulk_set supplied for custom " "collection_class implementation" ) def _inflate(self, proxy): creator = ( self.parent.creator and self.parent.creator or self.target_class ) if self.parent.getset_factory: getter, setter = self.parent.getset_factory( self.collection_class, self ) else: getter, setter = self.parent._default_getset(self.collection_class) proxy.creator = creator proxy.getter = getter proxy.setter = setter def _criterion_exists(self, criterion=None, **kwargs): is_has = kwargs.pop("is_has", None) target_assoc = self._unwrap_target_assoc_proxy if target_assoc is not None: inner = target_assoc._criterion_exists( criterion=criterion, **kwargs ) return self._comparator._criterion_exists(inner) if self._target_is_object: prop = getattr(self.target_class, self.value_attr) value_expr = prop._criterion_exists(criterion, **kwargs) else: if kwargs: raise exc.ArgumentError( "Can't apply keyword arguments to column-targeted " "association proxy; use ==" ) elif is_has and criterion is not None: raise exc.ArgumentError( "Non-empty has() not allowed for " "column-targeted association proxy; use ==" ) value_expr = criterion return self._comparator._criterion_exists(value_expr) def any(self, criterion=None, **kwargs): """Produce a proxied 'any' expression using EXISTS. This expression will be a composed product using the :meth:`.RelationshipProperty.Comparator.any` and/or :meth:`.RelationshipProperty.Comparator.has` operators of the underlying proxied attributes. """ if self._unwrap_target_assoc_proxy is None and ( self.scalar and (not self._target_is_object or self._value_is_scalar) ): raise exc.InvalidRequestError( "'any()' not implemented for scalar " "attributes. Use has()." ) return self._criterion_exists( criterion=criterion, is_has=False, **kwargs ) def has(self, criterion=None, **kwargs): """Produce a proxied 'has' expression using EXISTS. This expression will be a composed product using the :meth:`.RelationshipProperty.Comparator.any` and/or :meth:`.RelationshipProperty.Comparator.has` operators of the underlying proxied attributes. """ if self._unwrap_target_assoc_proxy is None and ( not self.scalar or (self._target_is_object and not self._value_is_scalar) ): raise exc.InvalidRequestError( "'has()' not implemented for collections. " "Use any()." ) return self._criterion_exists( criterion=criterion, is_has=True, **kwargs ) def __repr__(self): return "%s(%r)" % (self.__class__.__name__, self.parent) class AmbiguousAssociationProxyInstance(AssociationProxyInstance): """an :class:`.AssociationProxyInstance` where we cannot determine the type of target object. """ _is_canonical = False def _ambiguous(self): raise AttributeError( "Association proxy %s.%s refers to an attribute '%s' that is not " "directly mapped on class %s; therefore this operation cannot " "proceed since we don't know what type of object is referred " "towards" % ( self.owning_class.__name__, self.target_collection, self.value_attr, self.target_class, ) ) def get(self, obj): if obj is None: return self else: return super(AmbiguousAssociationProxyInstance, self).get(obj) def __eq__(self, obj): self._ambiguous() def __ne__(self, obj): self._ambiguous() def any(self, criterion=None, **kwargs): self._ambiguous() def has(self, criterion=None, **kwargs): self._ambiguous() @util.memoized_property def _lookup_cache(self): # mapping of <subclass>->AssociationProxyInstance. # e.g. proxy is A-> A.b -> B -> B.b_attr, but B.b_attr doesn't exist; # only B1(B) and B2(B) have "b_attr", keys in here would be B1, B2 return {} def _non_canonical_get_for_object(self, parent_instance): if parent_instance is not None: actual_obj = getattr(parent_instance, self.target_collection) if actual_obj is not None: try: insp = inspect(actual_obj) except exc.NoInspectionAvailable: pass else: mapper = insp.mapper instance_class = mapper.class_ if instance_class not in self._lookup_cache: self._populate_cache(instance_class, mapper) try: return self._lookup_cache[instance_class] except KeyError: pass # no object or ambiguous object given, so return "self", which # is a proxy with generally only instance-level functionality return self def _populate_cache(self, instance_class, mapper): prop = orm.class_mapper(self.owning_class).get_property( self.target_collection ) if mapper.isa(prop.mapper): target_class = instance_class try: target_assoc = self._cls_unwrap_target_assoc_proxy( target_class, self.value_attr ) except AttributeError: pass else: self._lookup_cache[instance_class] = self._construct_for_assoc( target_assoc, self.parent, self.owning_class, target_class, self.value_attr, ) class ObjectAssociationProxyInstance(AssociationProxyInstance): """an :class:`.AssociationProxyInstance` that has an object as a target.""" _target_is_object = True _is_canonical = True def contains(self, obj): """Produce a proxied 'contains' expression using EXISTS. This expression will be a composed product using the :meth:`.RelationshipProperty.Comparator.any`, :meth:`.RelationshipProperty.Comparator.has`, and/or :meth:`.RelationshipProperty.Comparator.contains` operators of the underlying proxied attributes. """ target_assoc = self._unwrap_target_assoc_proxy if target_assoc is not None: return self._comparator._criterion_exists( target_assoc.contains(obj) if not target_assoc.scalar else target_assoc == obj ) elif ( self._target_is_object and self.scalar and not self._value_is_scalar ): return self._comparator.has( getattr(self.target_class, self.value_attr).contains(obj) ) elif self._target_is_object and self.scalar and self._value_is_scalar: raise exc.InvalidRequestError( "contains() doesn't apply to a scalar object endpoint; use ==" ) else: return self._comparator._criterion_exists(**{self.value_attr: obj}) def __eq__(self, obj): # note the has() here will fail for collections; eq_() # is only allowed with a scalar. if obj is None: return or_( self._comparator.has(**{self.value_attr: obj}), self._comparator == None, ) else: return self._comparator.has(**{self.value_attr: obj}) def __ne__(self, obj): # note the has() here will fail for collections; eq_() # is only allowed with a scalar. return self._comparator.has( getattr(self.target_class, self.value_attr) != obj ) class ColumnAssociationProxyInstance( ColumnOperators, AssociationProxyInstance ): """an :class:`.AssociationProxyInstance` that has a database column as a target. """ _target_is_object = False _is_canonical = True def __eq__(self, other): # special case "is None" to check for no related row as well expr = self._criterion_exists( self.remote_attr.operate(operator.eq, other) ) if other is None: return or_(expr, self._comparator == None) else: return expr def operate(self, op, *other, **kwargs): return self._criterion_exists( self.remote_attr.operate(op, *other, **kwargs) ) class _lazy_collection(object): def __init__(self, obj, target): self.parent = obj self.target = target def __call__(self): return getattr(self.parent, self.target) def __getstate__(self): return {"obj": self.parent, "target": self.target} def __setstate__(self, state): self.parent = state["obj"] self.target = state["target"] class _AssociationCollection(object): def __init__(self, lazy_collection, creator, getter, setter, parent): """Constructs an _AssociationCollection. This will always be a subclass of either _AssociationList, _AssociationSet, or _AssociationDict. lazy_collection A callable returning a list-based collection of entities (usually an object attribute managed by a SQLAlchemy relationship()) creator A function that creates new target entities. Given one parameter: value. This assertion is assumed:: obj = creator(somevalue) assert getter(obj) == somevalue getter A function. Given an associated object, return the 'value'. setter A function. Given an associated object and a value, store that value on the object. """ self.lazy_collection = lazy_collection self.creator = creator self.getter = getter self.setter = setter self.parent = parent col = property(lambda self: self.lazy_collection()) def __len__(self): return len(self.col) def __bool__(self): return bool(self.col) __nonzero__ = __bool__ def __getstate__(self): return {"parent": self.parent, "lazy_collection": self.lazy_collection} def __setstate__(self, state): self.parent = state["parent"] self.lazy_collection = state["lazy_collection"] self.parent._inflate(self) def _bulk_replace(self, assoc_proxy, values): self.clear() assoc_proxy._set(self, values) class _AssociationList(_AssociationCollection): """Generic, converting, list-to-list proxy.""" def _create(self, value): return self.creator(value) def _get(self, object_): return self.getter(object_) def _set(self, object_, value): return self.setter(object_, value) def __getitem__(self, index): if not isinstance(index, slice): return self._get(self.col[index]) else: return [self._get(member) for member in self.col[index]] def __setitem__(self, index, value): if not isinstance(index, slice): self._set(self.col[index], value) else: if index.stop is None: stop = len(self) elif index.stop < 0: stop = len(self) + index.stop else: stop = index.stop step = index.step or 1 start = index.start or 0 rng = list(range(index.start or 0, stop, step)) if step == 1: for i in rng: del self[start] i = start for item in value: self.insert(i, item) i += 1 else: if len(value) != len(rng): raise ValueError( "attempt to assign sequence of size %s to " "extended slice of size %s" % (len(value), len(rng)) ) for i, item in zip(rng, value): self._set(self.col[i], item) def __delitem__(self, index): del self.col[index] def __contains__(self, value): for member in self.col: # testlib.pragma exempt:__eq__ if self._get(member) == value: return True return False def __getslice__(self, start, end): return [self._get(member) for member in self.col[start:end]] def __setslice__(self, start, end, values): members = [self._create(v) for v in values] self.col[start:end] = members def __delslice__(self, start, end): del self.col[start:end] def __iter__(self): """Iterate over proxied values. For the actual domain objects, iterate over .col instead or just use the underlying collection directly from its property on the parent. """ for member in self.col: yield self._get(member) return def append(self, value): col = self.col item = self._create(value) col.append(item) def count(self, value): return sum( [ 1 for _ in util.itertools_filter( lambda v: v == value, iter(self) ) ] ) def extend(self, values): for v in values: self.append(v) def insert(self, index, value): self.col[index:index] = [self._create(value)] def pop(self, index=-1): return self.getter(self.col.pop(index)) def remove(self, value): for i, val in enumerate(self): if val == value: del self.col[i] return raise ValueError("value not in list") def reverse(self): """Not supported, use reversed(mylist)""" raise NotImplementedError def sort(self): """Not supported, use sorted(mylist)""" raise NotImplementedError def clear(self): del self.col[0 : len(self.col)] def __eq__(self, other): return list(self) == other def __ne__(self, other): return list(self) != other def __lt__(self, other): return list(self) < other def __le__(self, other): return list(self) <= other def __gt__(self, other): return list(self) > other def __ge__(self, other): return list(self) >= other def __cmp__(self, other): return util.cmp(list(self), other) def __add__(self, iterable): try: other = list(iterable) except TypeError: return NotImplemented return list(self) + other def __radd__(self, iterable): try: other = list(iterable) except TypeError: return NotImplemented return other + list(self) def __mul__(self, n): if not isinstance(n, int): return NotImplemented return list(self) * n __rmul__ = __mul__ def __iadd__(self, iterable): self.extend(iterable) return self def __imul__(self, n): # unlike a regular list *=, proxied __imul__ will generate unique # backing objects for each copy. *= on proxied lists is a bit of # a stretch anyhow, and this interpretation of the __imul__ contract # is more plausibly useful than copying the backing objects. if not isinstance(n, int): return NotImplemented if n == 0: self.clear() elif n > 1: self.extend(list(self) * (n - 1)) return self def index(self, item, *args): return list(self).index(item, *args) def copy(self): return list(self) def __repr__(self): return repr(list(self)) def __hash__(self): raise TypeError("%s objects are unhashable" % type(self).__name__) for func_name, func in list(locals().items()): if ( callable(func) and func.__name__ == func_name and not func.__doc__ and hasattr(list, func_name) ): func.__doc__ = getattr(list, func_name).__doc__ del func_name, func _NotProvided = util.symbol("_NotProvided") class _AssociationDict(_AssociationCollection): """Generic, converting, dict-to-dict proxy.""" def _create(self, key, value): return self.creator(key, value) def _get(self, object_): return self.getter(object_) def _set(self, object_, key, value): return self.setter(object_, key, value) def __getitem__(self, key): return self._get(self.col[key]) def __setitem__(self, key, value): if key in self.col: self._set(self.col[key], key, value) else: self.col[key] = self._create(key, value) def __delitem__(self, key): del self.col[key] def __contains__(self, key): # testlib.pragma exempt:__hash__ return key in self.col def has_key(self, key): # testlib.pragma exempt:__hash__ return key in self.col def __iter__(self): return iter(self.col.keys()) def clear(self): self.col.clear() def __eq__(self, other): return dict(self) == other def __ne__(self, other): return dict(self) != other def __lt__(self, other): return dict(self) < other def __le__(self, other): return dict(self) <= other def __gt__(self, other): return dict(self) > other def __ge__(self, other): return dict(self) >= other def __cmp__(self, other): return util.cmp(dict(self), other) def __repr__(self): return repr(dict(self.items())) def get(self, key, default=None): try: return self[key] except KeyError: return default def setdefault(self, key, default=None): if key not in self.col: self.col[key] = self._create(key, default) return default else: return self[key] def keys(self): return self.col.keys() if util.py2k: def iteritems(self): return ((key, self._get(self.col[key])) for key in self.col) def itervalues(self): return (self._get(self.col[key]) for key in self.col) def iterkeys(self): return self.col.iterkeys() def values(self): return [self._get(member) for member in self.col.values()] def items(self): return [(k, self._get(self.col[k])) for k in self] else: def items(self): return ((key, self._get(self.col[key])) for key in self.col) def values(self): return (self._get(self.col[key]) for key in self.col) def pop(self, key, default=_NotProvided): if default is _NotProvided: member = self.col.pop(key) else: member = self.col.pop(key, default) return self._get(member) def popitem(self): item = self.col.popitem() return (item[0], self._get(item[1])) def update(self, *a, **kw): if len(a) > 1: raise TypeError( "update expected at most 1 arguments, got %i" % len(a) ) elif len(a) == 1: seq_or_map = a[0] # discern dict from sequence - took the advice from # https://www.voidspace.org.uk/python/articles/duck_typing.shtml # still not perfect :( if hasattr(seq_or_map, "keys"): for item in seq_or_map: self[item] = seq_or_map[item] else: try: for k, v in seq_or_map: self[k] = v except ValueError as err: util.raise_( ValueError( "dictionary update sequence " "requires 2-element tuples" ), replace_context=err, ) for key, value in kw: self[key] = value def _bulk_replace(self, assoc_proxy, values): existing = set(self) constants = existing.intersection(values or ()) additions = set(values or ()).difference(constants) removals = existing.difference(constants) for key, member in values.items() or (): if key in additions: self[key] = member elif key in constants: self[key] = member for key in removals: del self[key] def copy(self): return dict(self.items()) def __hash__(self): raise TypeError("%s objects are unhashable" % type(self).__name__) for func_name, func in list(locals().items()): if ( callable(func) and func.__name__ == func_name and not func.__doc__ and hasattr(dict, func_name) ): func.__doc__ = getattr(dict, func_name).__doc__ del func_name, func class _AssociationSet(_AssociationCollection): """Generic, converting, set-to-set proxy.""" def _create(self, value): return self.creator(value) def _get(self, object_): return self.getter(object_) def __len__(self): return len(self.col) def __bool__(self): if self.col: return True else: return False __nonzero__ = __bool__ def __contains__(self, value): for member in self.col: # testlib.pragma exempt:__eq__ if self._get(member) == value: return True return False def __iter__(self): """Iterate over proxied values. For the actual domain objects, iterate over .col instead or just use the underlying collection directly from its property on the parent. """ for member in self.col: yield self._get(member) return def add(self, value): if value not in self: self.col.add(self._create(value)) # for discard and remove, choosing a more expensive check strategy rather # than call self.creator() def discard(self, value): for member in self.col: if self._get(member) == value: self.col.discard(member) break def remove(self, value): for member in self.col: if self._get(member) == value: self.col.discard(member) return raise KeyError(value) def pop(self): if not self.col: raise KeyError("pop from an empty set") member = self.col.pop() return self._get(member) def update(self, other): for value in other: self.add(value) def _bulk_replace(self, assoc_proxy, values): existing = set(self) constants = existing.intersection(values or ()) additions = set(values or ()).difference(constants) removals = existing.difference(constants) appender = self.add remover = self.remove for member in values or (): if member in additions: appender(member) elif member in constants: appender(member) for member in removals: remover(member) def __ior__(self, other): if not collections._set_binops_check_strict(self, other): return NotImplemented for value in other: self.add(value) return self def _set(self): return set(iter(self)) def union(self, other): return set(self).union(other) __or__ = union def difference(self, other): return set(self).difference(other) __sub__ = difference def difference_update(self, other): for value in other: self.discard(value) def __isub__(self, other): if not collections._set_binops_check_strict(self, other): return NotImplemented for value in other: self.discard(value) return self def intersection(self, other): return set(self).intersection(other) __and__ = intersection def intersection_update(self, other): want, have = self.intersection(other), set(self) remove, add = have - want, want - have for value in remove: self.remove(value) for value in add: self.add(value) def __iand__(self, other): if not collections._set_binops_check_strict(self, other): return NotImplemented want, have = self.intersection(other), set(self) remove, add = have - want, want - have for value in remove: self.remove(value) for value in add: self.add(value) return self def symmetric_difference(self, other): return set(self).symmetric_difference(other) __xor__ = symmetric_difference def symmetric_difference_update(self, other): want, have = self.symmetric_difference(other), set(self) remove, add = have - want, want - have for value in remove: self.remove(value) for value in add: self.add(value) def __ixor__(self, other): if not collections._set_binops_check_strict(self, other): return NotImplemented want, have = self.symmetric_difference(other), set(self) remove, add = have - want, want - have for value in remove: self.remove(value) for value in add: self.add(value) return self def issubset(self, other): return set(self).issubset(other) def issuperset(self, other): return set(self).issuperset(other) def clear(self): self.col.clear() def copy(self): return set(self) def __eq__(self, other): return set(self) == other def __ne__(self, other): return set(self) != other def __lt__(self, other): return set(self) < other def __le__(self, other): return set(self) <= other def __gt__(self, other): return set(self) > other def __ge__(self, other): return set(self) >= other def __repr__(self): return repr(set(self)) def __hash__(self): raise TypeError("%s objects are unhashable" % type(self).__name__) for func_name, func in list(locals().items()): if ( callable(func) and func.__name__ == func_name and not func.__doc__ and hasattr(set, func_name) ): func.__doc__ = getattr(set, func_name).__doc__ del func_name, func