import ruamel.yaml
import six
import inspect
from yamlize.round_trip_data import RoundTripData
from yamlize.yamlizing_error import YamlizingError
class Yamlizable(object):
__slots__ = ()
def __getstate__(self):
state = {}
if hasattr(self, "__dict__"):
state.update(self.__dict__)
applied_slots = set((None,)) # populated with None
for cls in reversed(type(self).__mro__):
cls_slots = getattr(cls, "__slots__", None)
if cls_slots in applied_slots:
continue
applied_slots.add(cls_slots)
for attr_name in cls_slots:
if attr_name.startswith("__"):
attr_name = "_{}{}".format(cls.__name__, attr_name)
while attr_name.startswith("__"):
attr_name = attr_name[1:]
if attr_name in state:
continue
state[attr_name] = getattr(self, attr_name)
return state
def __setstate__(self, state):
for k, v in state.items():
setattr(self, k, v)
@classmethod
def load(cls, stream, Loader=ruamel.yaml.RoundTripLoader):
# can't use ruamel.yaml.load because I need a Resolver/loader for
# resolving non-string types
loader = Loader(stream)
try:
node = loader.get_single_node()
return cls.from_yaml(loader, node, None)
finally:
loader.dispose()
@classmethod
def dump(cls, data, stream=None, Dumper=ruamel.yaml.RoundTripDumper):
# can't use ruamel.yaml.load because I need a Resolver/loader for
# resolving non-string types
convert_to_yaml = stream is None
stream = stream or six.StringIO()
dumper = Dumper(stream)
try:
dumper._serializer.open()
root_node = cls.to_yaml(dumper, data)
dumper.serialize(root_node)
dumper._serializer.close()
finally:
try:
dumper._emitter.dispose()
except AttributeError:
raise
dumper.dispose() # cyaml
if convert_to_yaml:
return stream.getvalue()
return None
@classmethod
def from_yaml(cls, loader, node, round_trip_data):
raise NotImplementedError
@classmethod
def to_yaml(cls, dumper, self, round_trip_data):
raise NotImplementedError
class Typed(type):
__types = {}
def __new__(mcls, type_, from_yaml=None, to_yaml=None, compare_after_cast=True):
if issubclass(type_, Yamlizable):
return type_
if type_ not in mcls.__types:
mcls.__types[type_] = type(
"Yamlizable" + type_.__name__,
(Strong,),
{
"_Strong__type": type_,
"_Strong__from_yaml": staticmethod(from_yaml),
"_Strong__to_yaml": staticmethod(to_yaml),
"_Strong__compare_after_cast": compare_after_cast,
},
)
return mcls.__types[type_]
class Strong(Yamlizable):
"""
The Strongly typed Yamlizable subclass. Subclasses of Strong are dynamically created on demand
when someone creates an Attribute with ``type=sometype``.
Note that there may never be an instance of a Strongint. If there were, it would actually get
more complicated because we currently rely upon ``ruamel.yaml`` to give us rational representers
and composers. If an ``int`` was cast to a ``Strongint``, then we would need to add a
representer into the ``ruamel.yaml.Dumper``.
"""
__slots__ = ()
__type = None
__from_yaml = None
__to_yaml = None
__compare_after_cast = None
def __new__(cls, obj):
# this is really only ever called to cast an object that is not the correct type to the
# correct type. We generally assume that the correct type is the Strong subclass, but as
# stated above, it is easier to keep data as primitives.
if isinstance(obj, (cls, cls.__type)):
return obj
return cls.__type(obj)
@classmethod
def from_yaml(cls, loader, node, round_trip_data):
if cls.__from_yaml is not None:
data = cls.__from_yaml.__call__(loader, node, round_trip_data)
else:
data = loader.construct_object(node, deep=True)
if not isinstance(data, cls.__type):
try:
new_value = cls.__type(data) # to coerce to correct type
except Exception:
raise YamlizingError(
"Failed to coerce data `{}` to type `{}`".format(data, cls.__type)
)
if cls.__compare_after_cast:
if new_value != data:
# common case for Attribute(type=str, default=None) ... str(None) != 'None'
raise YamlizingError(
"Coerced `{}` to `{}`, but the new value `{}` is not equal to old `{}`."
.format(type(data), type(new_value), new_value, data),
node,
)
data = new_value
round_trip_data[data] = RoundTripData(node)
return data
@classmethod
def to_yaml(cls, dumper, data, round_trip_data):
if not isinstance(data, cls.__type) or (
cls.__type in (int, float, bool) and cls.__type != type(data)
):
try:
new_value = cls.__type(data) # to coerce to correct type
except Exception:
raise YamlizingError(
"Failed to coerce data `{}` to type `{}`".format(data, cls)
)
if cls.__compare_after_cast:
try:
if new_value == data:
data = new_value
except Exception:
pass
if cls.__to_yaml is not None:
node = cls.__to_yaml.__call__(dumper, data, round_trip_data)
else:
node = dumper.represent_data(
data if cls.__to_yaml is None else cls.__to_yaml(data)
)
round_trip_data[data].apply(node)
return node
Dynamic = Typed(object)