263 lines
9.5 KiB
Python
263 lines
9.5 KiB
Python
from pyrsistent._checked_types import (InvariantException, CheckedType, _restore_pickle, store_invariants)
|
|
from pyrsistent._field_common import (
|
|
set_fields, check_type, is_field_ignore_extra_complaint, PFIELD_NO_INITIAL, serialize, check_global_invariants
|
|
)
|
|
from pyrsistent._transformations import transform
|
|
|
|
|
|
def _is_pclass(bases):
|
|
return len(bases) == 1 and bases[0] == CheckedType
|
|
|
|
|
|
class PClassMeta(type):
|
|
def __new__(mcs, name, bases, dct):
|
|
set_fields(dct, bases, name='_pclass_fields')
|
|
store_invariants(dct, bases, '_pclass_invariants', '__invariant__')
|
|
dct['__slots__'] = ('_pclass_frozen',) + tuple(key for key in dct['_pclass_fields'])
|
|
|
|
# There must only be one __weakref__ entry in the inheritance hierarchy,
|
|
# lets put it on the top level class.
|
|
if _is_pclass(bases):
|
|
dct['__slots__'] += ('__weakref__',)
|
|
|
|
return super(PClassMeta, mcs).__new__(mcs, name, bases, dct)
|
|
|
|
_MISSING_VALUE = object()
|
|
|
|
|
|
def _check_and_set_attr(cls, field, name, value, result, invariant_errors):
|
|
check_type(cls, field, name, value)
|
|
is_ok, error_code = field.invariant(value)
|
|
if not is_ok:
|
|
invariant_errors.append(error_code)
|
|
else:
|
|
setattr(result, name, value)
|
|
|
|
|
|
class PClass(CheckedType, metaclass=PClassMeta):
|
|
"""
|
|
A PClass is a python class with a fixed set of specified fields. PClasses are declared as python classes inheriting
|
|
from PClass. It is defined the same way that PRecords are and behaves like a PRecord in all aspects except that it
|
|
is not a PMap and hence not a collection but rather a plain Python object.
|
|
|
|
|
|
More documentation and examples of PClass usage is available at https://github.com/tobgu/pyrsistent
|
|
"""
|
|
def __new__(cls, **kwargs): # Support *args?
|
|
result = super(PClass, cls).__new__(cls)
|
|
factory_fields = kwargs.pop('_factory_fields', None)
|
|
ignore_extra = kwargs.pop('ignore_extra', None)
|
|
missing_fields = []
|
|
invariant_errors = []
|
|
for name, field in cls._pclass_fields.items():
|
|
if name in kwargs:
|
|
if factory_fields is None or name in factory_fields:
|
|
if is_field_ignore_extra_complaint(PClass, field, ignore_extra):
|
|
value = field.factory(kwargs[name], ignore_extra=ignore_extra)
|
|
else:
|
|
value = field.factory(kwargs[name])
|
|
else:
|
|
value = kwargs[name]
|
|
_check_and_set_attr(cls, field, name, value, result, invariant_errors)
|
|
del kwargs[name]
|
|
elif field.initial is not PFIELD_NO_INITIAL:
|
|
initial = field.initial() if callable(field.initial) else field.initial
|
|
_check_and_set_attr(
|
|
cls, field, name, initial, result, invariant_errors)
|
|
elif field.mandatory:
|
|
missing_fields.append('{0}.{1}'.format(cls.__name__, name))
|
|
|
|
if invariant_errors or missing_fields:
|
|
raise InvariantException(tuple(invariant_errors), tuple(missing_fields), 'Field invariant failed')
|
|
|
|
if kwargs:
|
|
raise AttributeError("'{0}' are not among the specified fields for {1}".format(
|
|
', '.join(kwargs), cls.__name__))
|
|
|
|
check_global_invariants(result, cls._pclass_invariants)
|
|
|
|
result._pclass_frozen = True
|
|
return result
|
|
|
|
def set(self, *args, **kwargs):
|
|
"""
|
|
Set a field in the instance. Returns a new instance with the updated value. The original instance remains
|
|
unmodified. Accepts key-value pairs or single string representing the field name and a value.
|
|
|
|
>>> from pyrsistent import PClass, field
|
|
>>> class AClass(PClass):
|
|
... x = field()
|
|
...
|
|
>>> a = AClass(x=1)
|
|
>>> a2 = a.set(x=2)
|
|
>>> a3 = a.set('x', 3)
|
|
>>> a
|
|
AClass(x=1)
|
|
>>> a2
|
|
AClass(x=2)
|
|
>>> a3
|
|
AClass(x=3)
|
|
"""
|
|
if args:
|
|
kwargs[args[0]] = args[1]
|
|
|
|
factory_fields = set(kwargs)
|
|
|
|
for key in self._pclass_fields:
|
|
if key not in kwargs:
|
|
value = getattr(self, key, _MISSING_VALUE)
|
|
if value is not _MISSING_VALUE:
|
|
kwargs[key] = value
|
|
|
|
return self.__class__(_factory_fields=factory_fields, **kwargs)
|
|
|
|
@classmethod
|
|
def create(cls, kwargs, _factory_fields=None, ignore_extra=False):
|
|
"""
|
|
Factory method. Will create a new PClass of the current type and assign the values
|
|
specified in kwargs.
|
|
|
|
:param ignore_extra: A boolean which when set to True will ignore any keys which appear in kwargs that are not
|
|
in the set of fields on the PClass.
|
|
"""
|
|
if isinstance(kwargs, cls):
|
|
return kwargs
|
|
|
|
if ignore_extra:
|
|
kwargs = {k: kwargs[k] for k in cls._pclass_fields if k in kwargs}
|
|
|
|
return cls(_factory_fields=_factory_fields, ignore_extra=ignore_extra, **kwargs)
|
|
|
|
def serialize(self, format=None):
|
|
"""
|
|
Serialize the current PClass using custom serializer functions for fields where
|
|
such have been supplied.
|
|
"""
|
|
result = {}
|
|
for name in self._pclass_fields:
|
|
value = getattr(self, name, _MISSING_VALUE)
|
|
if value is not _MISSING_VALUE:
|
|
result[name] = serialize(self._pclass_fields[name].serializer, format, value)
|
|
|
|
return result
|
|
|
|
def transform(self, *transformations):
|
|
"""
|
|
Apply transformations to the currency PClass. For more details on transformations see
|
|
the documentation for PMap. Transformations on PClasses do not support key matching
|
|
since the PClass is not a collection. Apart from that the transformations available
|
|
for other persistent types work as expected.
|
|
"""
|
|
return transform(self, transformations)
|
|
|
|
def __eq__(self, other):
|
|
if isinstance(other, self.__class__):
|
|
for name in self._pclass_fields:
|
|
if getattr(self, name, _MISSING_VALUE) != getattr(other, name, _MISSING_VALUE):
|
|
return False
|
|
|
|
return True
|
|
|
|
return NotImplemented
|
|
|
|
def __ne__(self, other):
|
|
return not self == other
|
|
|
|
def __hash__(self):
|
|
# May want to optimize this by caching the hash somehow
|
|
return hash(tuple((key, getattr(self, key, _MISSING_VALUE)) for key in self._pclass_fields))
|
|
|
|
def __setattr__(self, key, value):
|
|
if getattr(self, '_pclass_frozen', False):
|
|
raise AttributeError("Can't set attribute, key={0}, value={1}".format(key, value))
|
|
|
|
super(PClass, self).__setattr__(key, value)
|
|
|
|
def __delattr__(self, key):
|
|
raise AttributeError("Can't delete attribute, key={0}, use remove()".format(key))
|
|
|
|
def _to_dict(self):
|
|
result = {}
|
|
for key in self._pclass_fields:
|
|
value = getattr(self, key, _MISSING_VALUE)
|
|
if value is not _MISSING_VALUE:
|
|
result[key] = value
|
|
|
|
return result
|
|
|
|
def __repr__(self):
|
|
return "{0}({1})".format(self.__class__.__name__,
|
|
', '.join('{0}={1}'.format(k, repr(v)) for k, v in self._to_dict().items()))
|
|
|
|
def __reduce__(self):
|
|
# Pickling support
|
|
data = dict((key, getattr(self, key)) for key in self._pclass_fields if hasattr(self, key))
|
|
return _restore_pickle, (self.__class__, data,)
|
|
|
|
def evolver(self):
|
|
"""
|
|
Returns an evolver for this object.
|
|
"""
|
|
return _PClassEvolver(self, self._to_dict())
|
|
|
|
def remove(self, name):
|
|
"""
|
|
Remove attribute given by name from the current instance. Raises AttributeError if the
|
|
attribute doesn't exist.
|
|
"""
|
|
evolver = self.evolver()
|
|
del evolver[name]
|
|
return evolver.persistent()
|
|
|
|
|
|
class _PClassEvolver(object):
|
|
__slots__ = ('_pclass_evolver_original', '_pclass_evolver_data', '_pclass_evolver_data_is_dirty', '_factory_fields')
|
|
|
|
def __init__(self, original, initial_dict):
|
|
self._pclass_evolver_original = original
|
|
self._pclass_evolver_data = initial_dict
|
|
self._pclass_evolver_data_is_dirty = False
|
|
self._factory_fields = set()
|
|
|
|
def __getitem__(self, item):
|
|
return self._pclass_evolver_data[item]
|
|
|
|
def set(self, key, value):
|
|
if self._pclass_evolver_data.get(key, _MISSING_VALUE) is not value:
|
|
self._pclass_evolver_data[key] = value
|
|
self._factory_fields.add(key)
|
|
self._pclass_evolver_data_is_dirty = True
|
|
|
|
return self
|
|
|
|
def __setitem__(self, key, value):
|
|
self.set(key, value)
|
|
|
|
def remove(self, item):
|
|
if item in self._pclass_evolver_data:
|
|
del self._pclass_evolver_data[item]
|
|
self._factory_fields.discard(item)
|
|
self._pclass_evolver_data_is_dirty = True
|
|
return self
|
|
|
|
raise AttributeError(item)
|
|
|
|
def __delitem__(self, item):
|
|
self.remove(item)
|
|
|
|
def persistent(self):
|
|
if self._pclass_evolver_data_is_dirty:
|
|
return self._pclass_evolver_original.__class__(_factory_fields=self._factory_fields,
|
|
**self._pclass_evolver_data)
|
|
|
|
return self._pclass_evolver_original
|
|
|
|
def __setattr__(self, key, value):
|
|
if key not in self.__slots__:
|
|
self.set(key, value)
|
|
else:
|
|
super(_PClassEvolver, self).__setattr__(key, value)
|
|
|
|
def __getattr__(self, item):
|
|
return self[item]
|