1 # This file is part of NIT ( http://www.nitlanguage.org ).
3 # Copyright 2014 Alexis Laferrière <alexis.laf@xymus.net>
5 # Licensed under the Apache License, Version 2.0 (the "License");
6 # you may not use this file except in compliance with the License.
7 # You may obtain a copy of the License at
9 # http://www.apache.org/licenses/LICENSE-2.0
11 # Unless required by applicable law or agreed to in writing, software
12 # distributed under the License is distributed on an "AS IS" BASIS,
13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 # See the License for the specific language governing permissions and
15 # limitations under the License.
17 # Abstract services to serialize Nit objects to different formats
19 # This module declares the `serialize` annotation to mark Nit classes as serializable.
20 # For an introduction to this service, refer to the documentation of the `serialization` group.
21 # This documentation provides more technical information on interesting entitie of this module.
23 # Interesting entities for end users of serializable classes:
25 # * Serialize an instance subclass of `Serializable` with either
26 # `Serializer::serializable` and `Serializable::serialize`.
27 # * Deserialize an object using `Deserializer::deserialize`.
28 # The object type must the be checked with an `assert` or otherwise.
30 # Interesting entities to create custom serializable classes:
32 # * Subclass `Serializable` to declare a class as serializable and to customize
33 # the serialization and deserialization behavior.
34 # * Redefine `Serializable::core_serialize_to` to customize the serialization
35 # of the receiver class.
36 # * Redefine `Deserializer::deserialize_class` to customize the deserialization
37 # of a specific class by name.
39 # Interesting entities for serialization format:
41 # * Subclass `Serializer` and `Deserializer` with custom serices.
42 # * In `Serializer`, `serialize` and `serialize_reference` must be redefined.
43 # * In `Deserializer`; `deserialize`, `deserialize_attribute and
44 # `notify_of_creation` must be redefined.
45 module serialization
is
46 new_annotation auto_serializable
47 new_annotation serialize
48 new_annotation noserialize
49 new_annotation serialize_as
52 # Abstract serialization service to be sub-classed by specialized services.
54 # Entry point method of this service, serialize the `object`
56 # This method, and refinements, should handle `null` and probably
57 # use double dispatch to customize the bahavior per serializable objects.
58 fun serialize
(object
: nullable Serializable) is abstract
60 # Serialize an object, with full serialization or a simple reference
61 protected fun serialize_reference
(object
: Serializable) is abstract
63 # Serialize an attribute to compose a serializable object
65 # This method should be called from `Serializable::core_serialize_to`.
66 fun serialize_attribute
(name
: String, value
: nullable Object)
68 if not try_to_serialize
(value
) then
69 warn
("argument {name} of type {value.class_name} is not serializable.")
73 # Serialize `value` is possie, i.e. it is `Serializable` or `null`
74 fun try_to_serialize
(value
: nullable Object): Bool
76 if value
isa Serializable then
77 value
.serialize_to_or_delay
(self)
78 else if value
== null then
84 # Warn of problems and potential errors (such as if an attribute
85 # is not serializable)
86 fun warn
(msg
: String) do print
"Serialization warning: {msg}"
89 # Abstract deserialization service
91 # After initialization of one of its sub-classes, call `deserialize`
92 abstract class Deserializer
93 # Main method of this class, returns a Nit object
94 fun deserialize
: nullable Object is abstract
96 # Internal method to be implemented by sub-classes
97 fun deserialize_attribute
(name
: String): nullable Object is abstract
99 # Internal method called by objects in creation,
100 # to be implemented by sub-classes
101 fun notify_of_creation
(new_object
: Object) is abstract
103 # Deserialize the next available object as an instance of `class_name`
105 # Returns the deserialized object on success, aborts on error.
107 # This method should be redefined for each custom subclass of `Serializable`.
108 # All refinement should look for a precise `class_name` and call super
109 # on unsupported classes.
110 protected fun deserialize_class
(class_name
: String): nullable Object do
111 if class_name
== "Error" then return new Error.from_deserializer
(self)
112 return deserialize_class_intern
(class_name
)
115 # Generated service to deserialize the next available object as an instance of `class_name`
117 # Refinements to this method will be generated by the serialization phase.
118 # To avoid conflicts, there should not be any other refinements to this method.
119 # You can instead use `deserialize_class`.
120 protected fun deserialize_class_intern
(class_name
: String): nullable Object do
121 errors
.add
new Error("Deserialization Error: Doesn't know how to deserialize class \"{class_name}\
"")
125 # Should `self` keep trying to deserialize an object after an error?
127 # This behavior takes effect after each attribute deserialization with
128 # errors such as a missing attribute or the value is of the wrong type.
129 # If `keep_going`, the attribute will be skipped but the engine will
130 # deserialize the next attribute.
131 # If `not keep_going`, the engine stops deserializing right away.
133 # When at `true`, this may cause the accumulation of a lot of entries in `errors`.
136 var keep_going
: nullable Bool = null is writable
138 # Errors encountered in the last call to `deserialize`
139 var errors
= new Array[Error]
142 # Deserialization got wrong attribute names
143 class AttributeTypeError
146 # Parent object of the problematic attribute
149 # Name of the problematic attribute in `receiver`
150 var attribute_name
: String
152 # Deserialized object that isn't of the `expected_type`
153 var attribute
: nullable Object
155 # Name of the type expected for `attribute`
156 var expected_type
: String
160 var attribute
= attribute
161 var found_type
= if attribute
!= null then attribute
.class_name
else "null"
163 return "Deserialization Error: {
164 }Wrong type on `{receiver.class_name}::{attribute_name}` expected `{expected_type}`, got `{found_type}`"
168 # Instances of this class can be passed to `Serializer::serialize`
169 interface Serializable
170 # Serialize `self` to `serializer`
172 # This is a shortcut to `Serializer::serialize`.
173 fun serialize_to
(serializer
: Serializer) do serializer
.serialize
(self)
175 # Actual serialization of `self` to `serializer`
177 # This writes the full data of `self` to `serializer`.
179 # This method can be redefined in sub classes and refinements.
180 # It should use `Serializer::serialize_attribute` to to register real or
181 # logical attributes.
183 # Any refinement should have its equivalent refinement of
184 # `Deserializer::deserialize_class` to support this custom deserialization.
185 fun core_serialize_to
(serializer
: Serializer) do end
187 # Accept references or force direct serialization (using `serialize_to`)
189 # The subclass change the default behavior, which will accept references,
190 # to force to always serialize copies of `self`.
191 private fun serialize_to_or_delay
(v
: Serializer) do v
.serialize_reference
(self)
193 # Create an instance of this class from the `deserializer`
195 # This constructor is refined by subclasses to correctly build their instances.
196 init from_deserializer
(deserializer
: Deserializer) is nosuper
do end
199 redef interface Object
200 # Is `self` the same as `other` in a serialization context?
202 # Used to determine if an object has already been serialized.
203 fun is_same_serialized
(other
: nullable Object): Bool do return is_same_instance
(other
)
205 # Hash value use for serialization
207 # Used in combination with `is_same_serialized`. If two objects are the same
208 # in a serialization context, they must have the same `serialization_hash`.
209 fun serialization_hash
: Int do return object_id
212 # Instances of this class are not delayed and instead serialized immediately
213 # This applies mainly to `universal` types
214 interface DirectSerializable
217 redef fun serialize_to_or_delay
(v
) do serialize_to
(v
)
220 redef class Bool super DirectSerializable end
221 redef class Char super DirectSerializable end
222 redef class Int super DirectSerializable end
223 redef class Float super DirectSerializable end
224 redef class NativeString super DirectSerializable end
225 redef class Text super DirectSerializable end
226 redef class SimpleCollection[E
] super Serializable end
227 redef class Map[K
, V
] super Serializable end
229 redef class Couple[F
, S
]
232 redef init from_deserializer
(v
)
234 v
.notify_of_creation
self
235 var first
= v
.deserialize_attribute
("first")
236 var second
= v
.deserialize_attribute
("second")
240 redef fun core_serialize_to
(v
)
242 v
.serialize_attribute
("first", first
)
243 v
.serialize_attribute
("second", second
)
250 redef init from_deserializer
(v
)
252 v
.notify_of_creation
self
253 var item
= v
.deserialize_attribute
("item")
257 redef fun core_serialize_to
(v
)
259 v
.serialize_attribute
("item", first
)
266 redef init from_deserializer
(v
)
268 v
.notify_of_creation
self
270 var message
= v
.deserialize_attribute
("message")
271 if not message
isa String then message
= ""
274 var cause
= v
.deserialize_attribute
("cause")
275 if cause
isa nullable Error then self.cause
= cause
278 redef fun core_serialize_to
(v
)
280 v
.serialize_attribute
("message", message
)
281 v
.serialize_attribute
("cause", cause
)