Edit File: _field_common.py
import six from pyrsistent._checked_types import ( CheckedPMap, CheckedPSet, CheckedPVector, CheckedType, InvariantException, _restore_pickle, get_type, maybe_parse_user_type, maybe_parse_many_user_types, ) from pyrsistent._checked_types import optional as optional_type from pyrsistent._checked_types import wrap_invariant from pyrsistent._compat import Enum def set_fields(dct, bases, name): dct[name] = dict(sum([list(b.__dict__.get(name, {}).items()) for b in bases], [])) for k, v in list(dct.items()): if isinstance(v, _PField): dct[name][k] = v del dct[k] def check_global_invariants(subject, invariants): error_codes = tuple(error_code for is_ok, error_code in (invariant(subject) for invariant in invariants) if not is_ok) if error_codes: raise InvariantException(error_codes, (), 'Global invariant failed') def serialize(serializer, format, value): if isinstance(value, CheckedType) and serializer is PFIELD_NO_SERIALIZER: return value.serialize(format) return serializer(format, value) def check_type(destination_cls, field, name, value): if field.type and not any(isinstance(value, get_type(t)) for t in field.type): actual_type = type(value) message = "Invalid type for field {0}.{1}, was {2}".format(destination_cls.__name__, name, actual_type.__name__) raise PTypeError(destination_cls, name, field.type, actual_type, message) class _PField(object): __slots__ = ('type', 'invariant', 'initial', 'mandatory', '_factory', 'serializer') def __init__(self, type, invariant, initial, mandatory, factory, serializer): self.type = type self.invariant = invariant self.initial = initial self.mandatory = mandatory self._factory = factory self.serializer = serializer @property def factory(self): # If no factory is specified and the type is another CheckedType use the factory method of that CheckedType if self._factory is PFIELD_NO_FACTORY and len(self.type) == 1: typ = get_type(tuple(self.type)[0]) if issubclass(typ, CheckedType): return typ.create return self._factory PFIELD_NO_TYPE = () PFIELD_NO_INVARIANT = lambda _: (True, None) PFIELD_NO_FACTORY = lambda x: x PFIELD_NO_INITIAL = object() PFIELD_NO_SERIALIZER = lambda _, value: value PFIELD_NO_SERIALIZER = lambda _, value: value def field(type=PFIELD_NO_TYPE, invariant=PFIELD_NO_INVARIANT, initial=PFIELD_NO_INITIAL, mandatory=False, factory=PFIELD_NO_FACTORY, serializer=PFIELD_NO_SERIALIZER): """ Field specification factory for :py:class:`PRecord`. :param type: a type or iterable with types that are allowed for this field :param invariant: a function specifying an invariant that must hold for the field :param initial: value of field if not specified when instantiating the record :param mandatory: boolean specifying if the field is mandatory or not :param factory: function called when field is set. :param serializer: function that returns a serialized version of the field """ # NB: We have to check this predicate separately from the predicates in # `maybe_parse_user_type` et al. because this one is related to supporting # the argspec for `field`, while those are related to supporting the valid # ways to specify types. # Multiple types must be passed in one of the following containers. Note # that a type that is a subclass of one of these containers, like a # `collections.namedtuple`, will work as expected, since we check # `isinstance` and not `issubclass`. if isinstance(type, (list, set, tuple)): types = set(maybe_parse_many_user_types(type)) else: types = set(maybe_parse_user_type(type)) invariant_function = wrap_invariant(invariant) if invariant != PFIELD_NO_INVARIANT and callable(invariant) else invariant field = _PField(type=types, invariant=invariant_function, initial=initial, mandatory=mandatory, factory=factory, serializer=serializer) _check_field_parameters(field) return field def _check_field_parameters(field): for t in field.type: if not isinstance(t, type) and not isinstance(t, six.string_types): raise TypeError('Type parameter expected, not {0}'.format(type(t))) if field.initial is not PFIELD_NO_INITIAL and \ not callable(field.initial) and \ field.type and not any(isinstance(field.initial, t) for t in field.type): raise TypeError('Initial has invalid type {0}'.format(type(field.initial))) if not callable(field.invariant): raise TypeError('Invariant must be callable') if not callable(field.factory): raise TypeError('Factory must be callable') if not callable(field.serializer): raise TypeError('Serializer must be callable') class PTypeError(TypeError): """ Raised when trying to assign a value with a type that doesn't match the declared type. Attributes: source_class -- The class of the record field -- Field name expected_types -- Types allowed for the field actual_type -- The non matching type """ def __init__(self, source_class, field, expected_types, actual_type, *args, **kwargs): super(PTypeError, self).__init__(*args, **kwargs) self.source_class = source_class self.field = field self.expected_types = expected_types self.actual_type = actual_type SEQ_FIELD_TYPE_SUFFIXES = { CheckedPVector: "PVector", CheckedPSet: "PSet", } # Global dictionary to hold auto-generated field types: used for unpickling _seq_field_types = {} def _restore_seq_field_pickle(checked_class, item_type, data): """Unpickling function for auto-generated PVec/PSet field types.""" type_ = _seq_field_types[checked_class, item_type] return _restore_pickle(type_, data) def _types_to_names(types): """Convert a tuple of types to a human-readable string.""" return "".join(get_type(typ).__name__.capitalize() for typ in types) def _make_seq_field_type(checked_class, item_type): """Create a subclass of the given checked class with the given item type.""" type_ = _seq_field_types.get((checked_class, item_type)) if type_ is not None: return type_ class TheType(checked_class): __type__ = item_type def __reduce__(self): return (_restore_seq_field_pickle, (checked_class, item_type, list(self))) suffix = SEQ_FIELD_TYPE_SUFFIXES[checked_class] TheType.__name__ = _types_to_names(TheType._checked_types) + suffix _seq_field_types[checked_class, item_type] = TheType return TheType def _sequence_field(checked_class, item_type, optional, initial): """ Create checked field for either ``PSet`` or ``PVector``. :param checked_class: ``CheckedPSet`` or ``CheckedPVector``. :param item_type: The required type for the items in the set. :param optional: If true, ``None`` can be used as a value for this field. :param initial: Initial value to pass to factory. :return: A ``field`` containing a checked class. """ TheType = _make_seq_field_type(checked_class, item_type) if optional: def factory(argument): if argument is None: return None else: return TheType.create(argument) else: factory = TheType.create return field(type=optional_type(TheType) if optional else TheType, factory=factory, mandatory=True, initial=factory(initial)) def pset_field(item_type, optional=False, initial=()): """ Create checked ``PSet`` field. :param item_type: The required type for the items in the set. :param optional: If true, ``None`` can be used as a value for this field. :param initial: Initial value to pass to factory if no value is given for the field. :return: A ``field`` containing a ``CheckedPSet`` of the given type. """ return _sequence_field(CheckedPSet, item_type, optional, initial) def pvector_field(item_type, optional=False, initial=()): """ Create checked ``PVector`` field. :param item_type: The required type for the items in the vector. :param optional: If true, ``None`` can be used as a value for this field. :param initial: Initial value to pass to factory if no value is given for the field. :return: A ``field`` containing a ``CheckedPVector`` of the given type. """ return _sequence_field(CheckedPVector, item_type, optional, initial) _valid = lambda item: (True, "") # Global dictionary to hold auto-generated field types: used for unpickling _pmap_field_types = {} def _restore_pmap_field_pickle(key_type, value_type, data): """Unpickling function for auto-generated PMap field types.""" type_ = _pmap_field_types[key_type, value_type] return _restore_pickle(type_, data) def _make_pmap_field_type(key_type, value_type): """Create a subclass of CheckedPMap with the given key and value types.""" type_ = _pmap_field_types.get((key_type, value_type)) if type_ is not None: return type_ class TheMap(CheckedPMap): __key_type__ = key_type __value_type__ = value_type def __reduce__(self): return (_restore_pmap_field_pickle, (self.__key_type__, self.__value_type__, dict(self))) TheMap.__name__ = "{0}To{1}PMap".format( _types_to_names(TheMap._checked_key_types), _types_to_names(TheMap._checked_value_types)) _pmap_field_types[key_type, value_type] = TheMap return TheMap def pmap_field(key_type, value_type, optional=False, invariant=PFIELD_NO_INVARIANT): """ Create a checked ``PMap`` field. :param key: The required type for the keys of the map. :param value: The required type for the values of the map. :param optional: If true, ``None`` can be used as a value for this field. :param invariant: Pass-through to ``field``. :return: A ``field`` containing a ``CheckedPMap``. """ TheMap = _make_pmap_field_type(key_type, value_type) if optional: def factory(argument): if argument is None: return None else: return TheMap.create(argument) else: factory = TheMap.create return field(mandatory=True, initial=TheMap(), type=optional_type(TheMap) if optional else TheMap, factory=factory, invariant=invariant)
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