# See the License for the specific language governing permissions and
# limitations under the License.
-# Offers services to serialize a Nit objects to different persistent formats
+# Abstract services to serialize Nit objects to different formats
+#
+# This module declares the `serialize` annotation to mark Nit classes as serializable.
+# For an introduction to this service, refer to the documentation of the `serialization` group.
+# This documentation provides more technical information on interesting entitie of this module.
+#
+# Interesting entities for end users of serializable classes:
+#
+# * Serialize an instance subclass of `Serializable` with either
+# `Serializer::serializable` and `Serializable::serialize`.
+# * Deserialize an object using `Deserializer::deserialize`.
+# The object type must the be checked with an `assert` or otherwise.
+#
+# Interesting entities to create custom serializable classes:
+#
+# * Subclass `Serializable` to declare a class as serializable and to customize
+# the serialization and deserialization behavior.
+# * Redefine `Serializable::core_serialize_to` to customize the serialization
+# of the receiver class.
+# * Redefine `Deserializer::deserialize_class` to customize the deserialization
+# of a specific class by name.
+#
+# Interesting entities for serialization format:
+#
+# * Subclass `Serializer` and `Deserializer` with custom serices.
+# * In `Serializer`, `serialize` and `serialize_reference` must be redefined.
+# * In `Deserializer`; `deserialize`, `deserialize_attribute and
+# `notify_of_creation` must be redefined.
module serialization is
new_annotation auto_serializable
+ new_annotation serialize
+ new_annotation noserialize
end
# Abstract serialization service to be sub-classed by specialized services.
interface Serializer
- # Main method of this service, serialize the `object`
+ # Entry point method of this service, serialize the `object`
+ #
+ # This method, and refinements, should handle `null` and probably
+ # use double dispatch to customize the bahavior per serializable objects.
fun serialize(object: nullable Serializable) is abstract
- # Serialize an object as a "possible" reference, depending of the service
- fun serialize_reference(object: Serializable) is abstract
+ # Serialize an object, with full serialization or a simple reference
+ protected fun serialize_reference(object: Serializable) is abstract
- # Serialize an attribute, used by `Serializable::core_serialize_to`
+ # Serialize an attribute to compose a serializable object
+ #
+ # This method should be called from `Serializable::core_serialize_to`.
fun serialize_attribute(name: String, value: nullable Object)
do
if not try_to_serialize(value) then
- warn("argument {value.class_name}::{name} is not serializable.")
+ warn("argument {name} of type {value.class_name} is not serializable.")
end
end
# Abstract deserialization service
#
# After initialization of one of its sub-classes, call `deserialize`
-interface Deserializer
+abstract class Deserializer
# Main method of this class, returns a Nit object
fun deserialize: nullable Object is abstract
# to be implemented by sub-classes
fun notify_of_creation(new_object: Object) is abstract
- # Mainly generated method to return the next instance of the givent
- # class by name
- fun deserialize_class(class_name: String): Object do
- print "Error: doesn't know how to deserialize class \"{class_name}\""
- abort
+ # Deserialize the next available object as an instance of `class_name`
+ #
+ # Returns the deserialized object on success, aborts on error.
+ #
+ # This method should be redefined for each custom subclass of `Serializable`.
+ # All refinement should look for a precise `class_name` and call super
+ # on unsupported classes.
+ protected fun deserialize_class(class_name: String): nullable Object do
+ return deserialize_class_intern(class_name)
+ end
+
+ # Generated service to deserialize the next available object as an instance of `class_name`
+ #
+ # Refinements to this method will be generated by the serialization phase.
+ # To avoid conflicts, there should not be any other refinements to this method.
+ # You can instead use `deserialize_class`.
+ protected fun deserialize_class_intern(class_name: String): nullable Object do
+ errors.add new Error("Deserialization Error: Doesn't know how to deserialize class \"{class_name}\"")
+ return null
+ end
+
+ # Should `self` keep trying to deserialize an object after an error?
+ #
+ # This behavior takes effect after each attribute deserialization with
+ # errors such as a missing attribute or the value is of the wrong type.
+ # If `keep_going`, the attribute will be skipped but the engine will
+ # deserialize the next attribute.
+ # If `not keep_going`, the engine stops deserializing right away.
+ #
+ # When at `true`, this may cause the accumulation of a lot of entries in `errors`.
+ #
+ # Default at `true`.
+ var keep_going: nullable Bool = null is writable
+
+ # Errors encountered in the last call to `deserialize`
+ var errors = new Array[Error]
+end
+
+# Deserialization got wrong attribute names
+class AttributeTypeError
+ super Error
+
+ # Parent object of the problematic attribute
+ var receiver: Object
+
+ # Name of the problematic attribute in `receiver`
+ var attribute_name: String
+
+ # Deserialized object that isn't of the `expected_type`
+ var attribute: nullable Object
+
+ # Name of the type expected for `attribute`
+ var expected_type: String
+
+ redef fun to_s
+ do
+ var attribute = attribute
+ var found_type = if attribute != null then attribute.class_name else "null"
+
+ return "Deserialization Error: {
+ }Wrong type on `{receiver.class_name}::{attribute_name}` expected `{expected_type}`, got `{found_type}`"
end
end
# Instances of this class can be passed to `Serializer::serialize`
interface Serializable
- # Full or true serialization
- fun serialize_to(v: Serializer) do v.serialize(self)
+ # Serialize `self` to `serializer`
+ #
+ # This is a shortcut to `Serializer::serialize`.
+ fun serialize_to(serializer: Serializer) do serializer.serialize(self)
+
+ # Actual serialization of `self` to `serializer`
+ #
+ # This writes the full data of `self` to `serializer`.
+ #
+ # This method can be redefined in sub classes and refinements.
+ # It should use `Serializer::serialize_attribute` to to register real or
+ # logical attributes.
+ #
+ # Any refinement should have its equivalent refinement of
+ # `Deserializer::deserialize_class` to support this custom deserialization.
+ fun core_serialize_to(serializer: Serializer) do end
- # Body of the serialization of this class
- # Can be redefed in sub classes and refinements
- fun core_serialize_to(v: Serializer) do end
+ # Accept references or force direct serialization (using `serialize_to`)
+ #
+ # The subclass change the default behavior, which will accept references,
+ # to force to always serialize copies of `self`.
+ private fun serialize_to_or_delay(v: Serializer) do v.serialize_reference(self)
- # Whether full serialization (calls `serialize_to`) or place only references
- fun serialize_to_or_delay(v: Serializer) do v.serialize_reference(self)
+ # Create an instance of this class from the `deserializer`
+ #
+ # This constructor is refined by subclasses to correctly build their instances.
+ init from_deserializer(deserializer: Deserializer) is nosuper do end
+end
+
+redef interface Object
+ # Is `self` the same as `other` in a serialization context?
+ #
+ # Used to determine if an object has already been serialized.
+ fun is_same_serialized(other: nullable Object): Bool do return is_same_instance(other)
+
+ # Hash value use for serialization
+ #
+ # Used in combination with `is_same_serialized`. If two objects are the same
+ # in a serialization context, they must have the same `serialization_hash`.
+ fun serialization_hash: Int do return object_id
end
# Instances of this class are not delayed and instead serialized immediately
redef class Float super DirectSerializable end
redef class NativeString super DirectSerializable end
redef class String super DirectSerializable end
-redef class Array[E] super Serializable end
+redef class SimpleCollection[E] super Serializable end
+redef class Map[K, V] super Serializable end
+
+redef class Couple[F, S]
+ super Serializable
+
+ redef init from_deserializer(v)
+ do
+ v.notify_of_creation self
+ var first = v.deserialize_attribute("first")
+ var second = v.deserialize_attribute("second")
+ init(first, second)
+ end
+
+ redef fun core_serialize_to(v)
+ do
+ v.serialize_attribute("first", first)
+ v.serialize_attribute("second", second)
+ end
+end
+
+redef class Ref[E]
+ super Serializable
+
+ redef init from_deserializer(v)
+ do
+ v.notify_of_creation self
+ var item = v.deserialize_attribute("item")
+ init item
+ end
+
+ redef fun core_serialize_to(v)
+ do
+ v.serialize_attribute("item", first)
+ end
+end
nitlanguage / nit.git / blobdiff