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
51 # Abstract serialization service to be sub-classed by specialized services.
53 # Entry point method of this service, serialize the `object`
55 # This method, and refinements, should handle `null` and probably
56 # use double dispatch to customize the bahavior per serializable objects.
57 fun serialize
(object
: nullable Serializable) is abstract
59 # Serialize an object, with full serialization or a simple reference
60 protected fun serialize_reference
(object
: Serializable) is abstract
62 # Serialize an attribute to compose a serializable object
64 # This method should be called from `Serializable::core_serialize_to`.
65 fun serialize_attribute
(name
: String, value
: nullable Object)
67 if not try_to_serialize
(value
) then
68 warn
("argument {name} of type {value.class_name} is not serializable.")
72 # Serialize `value` is possie, i.e. it is `Serializable` or `null`
73 fun try_to_serialize
(value
: nullable Object): Bool
75 if value
isa Serializable then
76 value
.serialize_to_or_delay
(self)
77 else if value
== null then
83 # Warn of problems and potential errors (such as if an attribute
84 # is not serializable)
85 fun warn
(msg
: String) do print
"Serialization warning: {msg}"
88 # Abstract deserialization service
90 # After initialization of one of its sub-classes, call `deserialize`
91 abstract class Deserializer
92 # Main method of this class, returns a Nit object
93 fun deserialize
: nullable Object is abstract
95 # Internal method to be implemented by sub-classes
96 fun deserialize_attribute
(name
: String): nullable Object is abstract
98 # Internal method called by objects in creation,
99 # to be implemented by sub-classes
100 fun notify_of_creation
(new_object
: Object) is abstract
102 # Deserialize the next available object as an instance of `class_name`
104 # Returns the deserialized object on success, aborts on error.
106 # This method should be redefined for each custom subclass of `Serializable`.
107 # All refinement should look for a precise `class_name` and call super
108 # on unsupported classes.
109 protected fun deserialize_class
(class_name
: String): nullable Object do
110 if class_name
== "Error" then return new Error.from_deserializer
(self)
111 return deserialize_class_intern
(class_name
)
114 # Generated service to deserialize the next available object as an instance of `class_name`
116 # Refinements to this method will be generated by the serialization phase.
117 # To avoid conflicts, there should not be any other refinements to this method.
118 # You can instead use `deserialize_class`.
119 protected fun deserialize_class_intern
(class_name
: String): nullable Object do
120 errors
.add
new Error("Deserialization Error: Doesn't know how to deserialize class \"{class_name}\
"")
124 # Should `self` keep trying to deserialize an object after an error?
126 # This behavior takes effect after each attribute deserialization with
127 # errors such as a missing attribute or the value is of the wrong type.
128 # If `keep_going`, the attribute will be skipped but the engine will
129 # deserialize the next attribute.
130 # If `not keep_going`, the engine stops deserializing right away.
132 # When at `true`, this may cause the accumulation of a lot of entries in `errors`.
135 var keep_going
: nullable Bool = null is writable
137 # Errors encountered in the last call to `deserialize`
138 var errors
= new Array[Error]
141 # Deserialization got wrong attribute names
142 class AttributeTypeError
145 # Parent object of the problematic attribute
148 # Name of the problematic attribute in `receiver`
149 var attribute_name
: String
151 # Deserialized object that isn't of the `expected_type`
152 var attribute
: nullable Object
154 # Name of the type expected for `attribute`
155 var expected_type
: String
159 var attribute
= attribute
160 var found_type
= if attribute
!= null then attribute
.class_name
else "null"
162 return "Deserialization Error: {
163 }Wrong type on `{receiver.class_name}::{attribute_name}` expected `{expected_type}`, got `{found_type}`"
167 # Instances of this class can be passed to `Serializer::serialize`
168 interface Serializable
169 # Serialize `self` to `serializer`
171 # This is a shortcut to `Serializer::serialize`.
172 fun serialize_to
(serializer
: Serializer) do serializer
.serialize
(self)
174 # Actual serialization of `self` to `serializer`
176 # This writes the full data of `self` to `serializer`.
178 # This method can be redefined in sub classes and refinements.
179 # It should use `Serializer::serialize_attribute` to to register real or
180 # logical attributes.
182 # Any refinement should have its equivalent refinement of
183 # `Deserializer::deserialize_class` to support this custom deserialization.
184 fun core_serialize_to
(serializer
: Serializer) do end
186 # Accept references or force direct serialization (using `serialize_to`)
188 # The subclass change the default behavior, which will accept references,
189 # to force to always serialize copies of `self`.
190 private fun serialize_to_or_delay
(v
: Serializer) do v
.serialize_reference
(self)
192 # Create an instance of this class from the `deserializer`
194 # This constructor is refined by subclasses to correctly build their instances.
195 init from_deserializer
(deserializer
: Deserializer) is nosuper
do end
198 redef interface Object
199 # Is `self` the same as `other` in a serialization context?
201 # Used to determine if an object has already been serialized.
202 fun is_same_serialized
(other
: nullable Object): Bool do return is_same_instance
(other
)
204 # Hash value use for serialization
206 # Used in combination with `is_same_serialized`. If two objects are the same
207 # in a serialization context, they must have the same `serialization_hash`.
208 fun serialization_hash
: Int do return object_id
211 # Instances of this class are not delayed and instead serialized immediately
212 # This applies mainly to `universal` types
213 interface DirectSerializable
216 redef fun serialize_to_or_delay
(v
) do serialize_to
(v
)
219 redef class Bool super DirectSerializable end
220 redef class Char super DirectSerializable end
221 redef class Int super DirectSerializable end
222 redef class Float super DirectSerializable end
223 redef class NativeString super DirectSerializable end
224 redef class String super DirectSerializable end
225 redef class SimpleCollection[E
] super Serializable end
226 redef class Map[K
, V
] super Serializable end
228 redef class Couple[F
, S
]
231 redef init from_deserializer
(v
)
233 v
.notify_of_creation
self
234 var first
= v
.deserialize_attribute
("first")
235 var second
= v
.deserialize_attribute
("second")
239 redef fun core_serialize_to
(v
)
241 v
.serialize_attribute
("first", first
)
242 v
.serialize_attribute
("second", second
)
249 redef init from_deserializer
(v
)
251 v
.notify_of_creation
self
252 var item
= v
.deserialize_attribute
("item")
256 redef fun core_serialize_to
(v
)
258 v
.serialize_attribute
("item", first
)
265 redef init from_deserializer
(v
)
267 v
.notify_of_creation
self
269 var message
= v
.deserialize_attribute
("message")
270 if not message
isa String then message
= ""
273 var cause
= v
.deserialize_attribute
("cause")
274 if cause
isa nullable Error then self.cause
= cause
277 redef fun core_serialize_to
(v
)
279 v
.serialize_attribute
("message", message
)
280 v
.serialize_attribute
("cause", cause
)