from abc import ABC, abstractmethod from owrx.property.validators import Validator from owrx.property.filter import Filter, ByPropertyName import logging logger = logging.getLogger(__name__) class PropertyError(Exception): pass class PropertyDeletion(object): pass # a special object that will be sent in events when a deletion occured # it can also represent deletion of a key in internal storage, but should not be return from standard dict apis PropertyDeleted = PropertyDeletion() class Subscription(object): def __init__(self, subscriptee, name, subscriber): self.subscriptee = subscriptee self.name = name self.subscriber = subscriber def getName(self): return self.name def call(self, *args, **kwargs): self.subscriber(*args, **kwargs) def cancel(self): self.subscriptee.unwire(self) class PropertyManager(ABC): def __init__(self): self.subscribers = [] @abstractmethod def __getitem__(self, item): pass @abstractmethod def __setitem__(self, key, value): pass @abstractmethod def __contains__(self, item): pass @abstractmethod def __dict__(self): pass @abstractmethod def __delitem__(self, key): pass @abstractmethod def keys(self): pass @abstractmethod def values(self): pass @abstractmethod def items(self): pass def __len__(self): return self.__dict__().__len__() def filter(self, *props): return PropertyFilter(self, ByPropertyName(*props)) def readonly(self): return PropertyReadOnly(self) def wire(self, callback): sub = Subscription(self, None, callback) self.subscribers.append(sub) return sub def wireProperty(self, name, callback): sub = Subscription(self, name, callback) self.subscribers.append(sub) if name in self: sub.call(self[name]) return sub def unwire(self, sub): try: self.subscribers.remove(sub) except ValueError: # happens when already removed before pass return self def _fireCallbacks(self, changes): if not changes: return for c in self.subscribers: try: if c.getName() is None: c.call(changes) except Exception: logger.exception("exception while firing changes") for name in changes: for c in self.subscribers: try: if c.getName() == name: c.call(changes[name]) except Exception: logger.exception("exception while firing changes") class PropertyLayer(PropertyManager): def __init__(self, **kwargs): super().__init__() # copy, don't re-use self.properties = {k: v for k, v in kwargs.items()} def __contains__(self, name): return name in self.properties def __getitem__(self, name): return self.properties[name] def __setitem__(self, name, value): if name in self.properties and self.properties[name] == value: return self.properties[name] = value self._fireCallbacks({name: value}) def __dict__(self): return {k: v for k, v in self.properties.items()} def __delitem__(self, key): self.properties.__delitem__(key) self._fireCallbacks({key: PropertyDeleted}) def keys(self): return self.properties.keys() def values(self): return self.properties.values() def items(self): return self.properties.items() class PropertyFilter(PropertyManager): def __init__(self, pm: PropertyManager, filter: Filter): super().__init__() self.pm = pm self._filter = filter self.pm.wire(self.receiveEvent) def receiveEvent(self, changes): changesToForward = {name: value for name, value in changes.items() if self._filter.apply(name)} self._fireCallbacks(changesToForward) def __getitem__(self, item): if not self._filter.apply(item): raise KeyError(item) return self.pm.__getitem__(item) def __setitem__(self, key, value): if not self._filter.apply(key): raise KeyError(key) return self.pm.__setitem__(key, value) def __contains__(self, item): if not self._filter.apply(item): return False return self.pm.__contains__(item) def __dict__(self): return {k: v for k, v in self.pm.__dict__().items() if self._filter.apply(k)} def __delitem__(self, key): if not self._filter.apply(key): raise KeyError(key) return self.pm.__delitem__(key) def keys(self): return [k for k in self.pm.keys() if self._filter.apply(k)] def values(self): return [v for k, v in self.pm.items() if self._filter.apply(k)] def items(self): return self.__dict__().items() class PropertyDelegator(PropertyManager): def __init__(self, pm: PropertyManager): self.pm = pm self.subscription = self.pm.wire(self._fireCallbacks) super().__init__() def __getitem__(self, item): return self.pm.__getitem__(item) def __setitem__(self, key, value): return self.pm.__setitem__(key, value) def __contains__(self, item): return self.pm.__contains__(item) def __dict__(self): return self.pm.__dict__() def __delitem__(self, key): return self.pm.__delitem__(key) def keys(self): return self.pm.keys() def values(self): return self.pm.values() def items(self): return self.pm.items() class PropertyValidationError(PropertyError): def __init__(self, key, value): super().__init__('Invalid value for property "{key}": "{value}"'.format(key=key, value=str(value))) class PropertyValidator(PropertyDelegator): def __init__(self, pm: PropertyManager, validators=None): super().__init__(pm) if validators is None: self.validators = {} else: self.validators = {k: Validator.of(v) for k, v in validators.items()} def validate(self, key, value): if key not in self.validators: return if not self.validators[key].isValid(value): raise PropertyValidationError(key, value) def setValidator(self, key, validator): self.validators[key] = Validator.of(validator) def __setitem__(self, key, value): self.validate(key, value) return self.pm.__setitem__(key, value) class PropertyWriteError(PropertyError): def __init__(self, key): super().__init__('Key "{key}" is not writeable'.format(key=key)) class PropertyReadOnly(PropertyDelegator): def __setitem__(self, key, value): raise PropertyWriteError(key) class PropertyStack(PropertyManager): def __init__(self): super().__init__() self.layers = [] def addLayer(self, priority: int, pm: PropertyManager): """ highest priority = 0 """ self._fireCallbacks(self._addLayer(priority, pm)) def _addLayer(self, priority: int, pm: PropertyManager): changes = {} for key in pm.keys(): if key not in self or self[key] != pm[key]: changes[key] = pm[key] def eventClosure(changes): self.receiveEvent(pm, changes) sub = pm.wire(eventClosure) self.layers.append({"priority": priority, "props": pm, "sub": sub}) return changes def removeLayer(self, pm: PropertyManager): for layer in self.layers: if layer["props"] == pm: self._fireCallbacks(self._removeLayer(layer)) def _removeLayer(self, layer): layer["sub"].cancel() self.layers.remove(layer) changes = {} pm = layer["props"] for key in pm.keys(): if key in self: if self[key] != pm[key]: changes[key] = self[key] else: changes[key] = PropertyDeleted return changes def replaceLayer(self, priority: int, pm: PropertyManager): layers = [x for x in self.layers if x["priority"] == priority] originalState = self.__dict__() changes = self._removeLayer(layers[0]) if layers else {} changes = {**changes, **self._addLayer(priority, pm)} changes = {k: v for k, v in changes.items() if k not in originalState or originalState[k] != v} self._fireCallbacks(changes) def receiveEvent(self, layer, changes): changesToForward = {name: value for name, value in changes.items() if layer == self._getTopLayer(name)} # deletions need to be handled separately: # * send a deletion if the key was deleted in all layers # * send lower value if the key is still present in a lower layer deletionsToForward = { name: PropertyDeleted if self._getTopLayer(name, False) is None else self[name] for name, value in changes.items() if value is PropertyDeleted } self._fireCallbacks({**changesToForward, **deletionsToForward}) def _getTopLayer(self, item, fallback=True): layers = [la["props"] for la in sorted(self.layers, key=lambda l: l["priority"])] for m in layers: if item in m: return m # return top layer as fallback if fallback and layers: return layers[0] def __getitem__(self, item): layer = self._getTopLayer(item) return layer.__getitem__(item) def __setitem__(self, key, value): layer = self._getTopLayer(key) return layer.__setitem__(key, value) def __contains__(self, item): layer = self._getTopLayer(item) if layer: return layer.__contains__(item) return False def __dict__(self): return {k: self.__getitem__(k) for k in self.keys()} def __delitem__(self, key): for layer in self.layers: if layer["props"].__contains__(key): layer["props"].__delitem__(key) def keys(self): return set([key for l in self.layers for key in l["props"].keys()]) def values(self): return [self.__getitem__(k) for k in self.keys()] def items(self): return self.__dict__().items() class PropertyCarousel(PropertyDelegator): def __init__(self): # start with an empty dummy layer self.emptyLayer = PropertyLayer().readonly() super().__init__(self.emptyLayer) self.layers = {} def _getDefaultLayer(self): return self.emptyLayer def addLayer(self, key, value): if key in self.layers and self.layers[key] is self.pm: self.layers[key] = value # switch after introducing the new value self.switch(key) else: self.layers[key] = value def removeLayer(self, key): if key in self.layers and self.layers[key] is self.pm: self.switch() del self.layers[key] def switch(self, key=None): before = self.pm self.subscription.cancel() self.pm = self._getDefaultLayer() if key is None else self.layers[key] self.subscription = self.pm.wire(self._fireCallbacks) changes = {} for key in set(list(before.keys()) + list(self.keys())): if key not in self: changes[key] = PropertyDeleted else: if key not in before or before[key] != self[key]: changes[key] = self[key] self._fireCallbacks(changes)