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1 /*
2  * Copyright 2017-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
3  */
4 package kotlinx.serialization.modules
5 
6 import kotlinx.serialization.*
7 import kotlinx.serialization.internal.*
8 import kotlin.jvm.*
9 import kotlin.reflect.*
10 
11 /**
12  * Returns a [SerializersModule] which has one class with one [serializer] for [ContextualSerializer].
13  */
serializersModuleOfnull14 public fun <T : Any> serializersModuleOf(kClass: KClass<T>, serializer: KSerializer<T>): SerializersModule =
15     SerializersModule { contextual(kClass, serializer) }
16 
17 /**
18  * Returns a [SerializersModule] which has one class with one [serializer] for [ContextualSerializer].
19  */
serializersModuleOfnull20 public inline fun <reified T : Any> serializersModuleOf(serializer: KSerializer<T>): SerializersModule =
21     serializersModuleOf(T::class, serializer)
22 
23 /**
24  * A builder function for creating a [SerializersModule].
25  * Serializers can be added via [SerializersModuleBuilder.contextual] or [SerializersModuleBuilder.polymorphic].
26  * Since [SerializersModuleBuilder] also implements [SerialModuleCollector],
27  * it is possible to copy whole another module to this builder with [SerializersModule.dumpTo]
28  */
29 @Suppress("FunctionName")
30 public inline fun SerializersModule(builderAction: SerializersModuleBuilder.() -> Unit): SerializersModule {
31     val builder = SerializersModuleBuilder()
32     builder.builderAction()
33     return builder.build()
34 }
35 
36 /**
37  * A [SerializersModule] which is empty and returns `null` from each method.
38  */
39 @Suppress("FunctionName")
EmptySerializersModulenull40 public fun EmptySerializersModule(): SerializersModule = @Suppress("DEPRECATION") EmptySerializersModule
41 
42 /**
43  * A builder class for [SerializersModule] DSL. To create an instance of builder, use [SerializersModule] factory function.
44  */
45 @OptIn(ExperimentalSerializationApi::class)
46 public class SerializersModuleBuilder @PublishedApi internal constructor() : SerializersModuleCollector {
47     private val class2ContextualProvider: MutableMap<KClass<*>, ContextualProvider> = hashMapOf()
48     private val polyBase2Serializers: MutableMap<KClass<*>, MutableMap<KClass<*>, KSerializer<*>>> = hashMapOf()
49     private val polyBase2DefaultSerializerProvider: MutableMap<KClass<*>, PolymorphicSerializerProvider<*>> = hashMapOf()
50     private val polyBase2NamedSerializers: MutableMap<KClass<*>, MutableMap<String, KSerializer<*>>> = hashMapOf()
51     private val polyBase2DefaultDeserializerProvider: MutableMap<KClass<*>, PolymorphicDeserializerProvider<*>> = hashMapOf()
52 
53     /**
54      * Adds [serializer] associated with given [kClass] for contextual serialization.
55      * If [kClass] has generic type parameters, consider registering provider instead.
56      *
57      * Throws [SerializationException] if a module already has serializer or provider associated with a [kClass].
58      * To overwrite an already registered serializer, [SerializersModule.overwriteWith] can be used.
59      */
60     public override fun <T : Any> contextual(kClass: KClass<T>, serializer: KSerializer<T>): Unit =
61         registerSerializer(kClass, ContextualProvider.Argless(serializer))
62 
63     /**
64      * Registers [provider] associated with given generic [kClass] for contextual serialization.
65      * When a serializer is requested from a module, provider is being called with type arguments serializers
66      * of the particular [kClass] usage.
67      *
68      * Example:
69      * ```
70      * class Holder(@Contextual val boxI: Box<Int>, @Contextual val boxS: Box<String>)
71      *
72      * val module = SerializersModule {
73      *   // args[0] contains Int.serializer() or String.serializer(), depending on the property
74      *   contextual(Box::class) { args -> BoxSerializer(args[0]) }
75      * }
76      * ```
77      *
78      * Throws [SerializationException] if a module already has provider or serializer associated with a [kClass].
79      * To overwrite an already registered serializer, [SerializersModule.overwriteWith] can be used.
80      */
81     public override fun <T : Any> contextual(
82         kClass: KClass<T>,
83         provider: (typeArgumentsSerializers: List<KSerializer<*>>) -> KSerializer<*>
84     ): Unit = registerSerializer(kClass, ContextualProvider.WithTypeArguments(provider))
85 
86     /**
87      * Adds [serializer][actualSerializer] associated with given [actualClass] in the scope of [baseClass] for polymorphic serialization.
88      * Throws [SerializationException] if a module already has serializer associated with a [actualClass].
89      * To overwrite an already registered serializer, [SerializersModule.overwriteWith] can be used.
90      */
91     public override fun <Base : Any, Sub : Base> polymorphic(
92         baseClass: KClass<Base>,
93         actualClass: KClass<Sub>,
94         actualSerializer: KSerializer<Sub>
95     ) {
96         registerPolymorphicSerializer(baseClass, actualClass, actualSerializer)
97     }
98 
99     /**
100      * Adds a default serializers provider associated with the given [baseClass] to the resulting module.
101      * [defaultSerializerProvider] is invoked when no polymorphic serializers for `value` in the scope of [baseClass] were found.
102      *
103      * Default serializers provider affects only serialization process. To affect deserialization process, use
104      * [SerializersModuleBuilder.polymorphicDefaultDeserializer].
105      *
106      * [defaultSerializerProvider] can be stateful and lookup a serializer for the missing type dynamically.
107      */
108     public override fun <Base : Any> polymorphicDefaultSerializer(
109         baseClass: KClass<Base>,
110         defaultSerializerProvider: (value: Base) -> SerializationStrategy<Base>?
111     ) {
112         registerDefaultPolymorphicSerializer(baseClass, defaultSerializerProvider, false)
113     }
114 
115     /**
116      * Adds a default deserializers provider associated with the given [baseClass] to the resulting module.
117      * [defaultDeserializerProvider] is invoked when no polymorphic serializers associated with the `className`
118      * in the scope of [baseClass] were found. `className` could be `null` for formats that support nullable class discriminators
119      * (currently only `Json` with `useArrayPolymorphism` set to `false`).
120      *
121      * Default deserializers provider affects only deserialization process. To affect serialization process, use
122      * [SerializersModuleBuilder.polymorphicDefaultSerializer].
123      *
124      * [defaultDeserializerProvider] can be stateful and lookup a serializer for the missing type dynamically.
125      *
126      * @see PolymorphicModuleBuilder.defaultDeserializer
127      */
128     public override fun <Base : Any> polymorphicDefaultDeserializer(
129         baseClass: KClass<Base>,
130         defaultDeserializerProvider: (className: String?) -> DeserializationStrategy<Base>?
131     ) {
132         registerDefaultPolymorphicDeserializer(baseClass, defaultDeserializerProvider, false)
133     }
134 
135     /**
136      * Copies the content of [module] module into the current builder.
137      */
138     public fun include(module: SerializersModule) {
139         module.dumpTo(this)
140     }
141 
142     @JvmName("registerSerializer") // Don't mangle method name for prettier stack traces
143     internal fun <T : Any> registerSerializer(
144         forClass: KClass<T>,
145         provider: ContextualProvider,
146         allowOverwrite: Boolean = false
147     ) {
148         if (!allowOverwrite) {
149             val previous = class2ContextualProvider[forClass]
150             if (previous != null && previous != provider) {
151                 // How can we provide meaningful name for WithTypeArgumentsProvider ?
152                 throw SerializerAlreadyRegisteredException(
153                     "Contextual serializer or serializer provider for $forClass already registered in this module"
154                 )
155             }
156         }
157         class2ContextualProvider[forClass] = provider
158     }
159 
160     @JvmName("registerDefaultPolymorphicSerializer") // Don't mangle method name for prettier stack traces
161     internal fun <Base : Any> registerDefaultPolymorphicSerializer(
162         baseClass: KClass<Base>,
163         defaultSerializerProvider: (value: Base) -> SerializationStrategy<Base>?,
164         allowOverwrite: Boolean
165     ) {
166         val previous = polyBase2DefaultSerializerProvider[baseClass]
167         if (previous != null && previous != defaultSerializerProvider && !allowOverwrite) {
168             throw IllegalArgumentException("Default serializers provider for $baseClass is already registered: $previous")
169         }
170         polyBase2DefaultSerializerProvider[baseClass] = defaultSerializerProvider
171     }
172 
173     @JvmName("registerDefaultPolymorphicDeserializer") // Don't mangle method name for prettier stack traces
174     internal fun <Base : Any> registerDefaultPolymorphicDeserializer(
175         baseClass: KClass<Base>,
176         defaultDeserializerProvider: (className: String?) -> DeserializationStrategy<Base>?,
177         allowOverwrite: Boolean
178     ) {
179         val previous = polyBase2DefaultDeserializerProvider[baseClass]
180         if (previous != null && previous != defaultDeserializerProvider && !allowOverwrite) {
181             throw IllegalArgumentException("Default deserializers provider for $baseClass is already registered: $previous")
182         }
183         polyBase2DefaultDeserializerProvider[baseClass] = defaultDeserializerProvider
184     }
185 
186     @JvmName("registerPolymorphicSerializer") // Don't mangle method name for prettier stack traces
187     internal fun <Base : Any, Sub : Base> registerPolymorphicSerializer(
188         baseClass: KClass<Base>,
189         concreteClass: KClass<Sub>,
190         concreteSerializer: KSerializer<Sub>,
191         allowOverwrite: Boolean = false
192     ) {
193         // Check for overwrite
194         val name = concreteSerializer.descriptor.serialName
195         val baseClassSerializers = polyBase2Serializers.getOrPut(baseClass, ::hashMapOf)
196         val previousSerializer = baseClassSerializers[concreteClass]
197         val names = polyBase2NamedSerializers.getOrPut(baseClass, ::hashMapOf)
198         if (allowOverwrite) {
199             // Remove previous serializers from name mapping
200             if (previousSerializer != null) {
201                 names.remove(previousSerializer.descriptor.serialName)
202             }
203             // Update mappings
204             baseClassSerializers[concreteClass] = concreteSerializer
205             names[name] = concreteSerializer
206             return
207         }
208         // Overwrite prohibited
209         if (previousSerializer != null) {
210             if (previousSerializer != concreteSerializer) {
211                 throw SerializerAlreadyRegisteredException(baseClass, concreteClass)
212             } else {
213                 // Cleanup name mapping
214                 names.remove(previousSerializer.descriptor.serialName)
215             }
216         }
217         val previousByName = names[name]
218         if (previousByName != null) {
219             val conflictingClass = polyBase2Serializers[baseClass]!!.asSequence().find { it.value === previousByName }
220             throw IllegalArgumentException(
221                 "Multiple polymorphic serializers for base class '$baseClass' " +
222                         "have the same serial name '$name': '$concreteClass' and '$conflictingClass'"
223             )
224         }
225         // Overwrite if no conflicts
226         baseClassSerializers[concreteClass] = concreteSerializer
227         names[name] = concreteSerializer
228     }
229 
230     @PublishedApi
231     internal fun build(): SerializersModule =
232         SerialModuleImpl(class2ContextualProvider, polyBase2Serializers, polyBase2DefaultSerializerProvider, polyBase2NamedSerializers, polyBase2DefaultDeserializerProvider)
233 }
234 
235 /**
236  * Adds [serializer] associated with given type [T] for contextual serialization.
237  * Throws [SerializationException] if a module already has serializer associated with the given type.
238  * To overwrite an already registered serializer, [SerializersModule.overwriteWith] can be used.
239  */
contextualnull240 public inline fun <reified T : Any> SerializersModuleBuilder.contextual(serializer: KSerializer<T>): Unit =
241     contextual(T::class, serializer)
242 
243 /**
244  * Creates a builder to register subclasses of a given [baseClass] for polymorphic serialization.
245  * If [baseSerializer] is not null, registers it as a serializer for [baseClass],
246  * which is useful if the base class is serializable itself. To register subclasses,
247  * [PolymorphicModuleBuilder.subclass] builder function can be used.
248  *
249  * If a serializer already registered for the given KClass in the given scope, an [IllegalArgumentException] is thrown.
250  * To override registered serializers, combine built module with another using [SerializersModule.overwriteWith].
251  *
252  * @see PolymorphicSerializer
253  */
254 public inline fun <Base : Any> SerializersModuleBuilder.polymorphic(
255     baseClass: KClass<Base>,
256     baseSerializer: KSerializer<Base>? = null,
257     builderAction: PolymorphicModuleBuilder<Base>.() -> Unit = {}
258 ) {
259     val builder = PolymorphicModuleBuilder(baseClass, baseSerializer)
260     builder.builderAction()
261     builder.buildTo(this)
262 }
263 
264 private class SerializerAlreadyRegisteredException internal constructor(msg: String) : IllegalArgumentException(msg) {
265     internal constructor(
266         baseClass: KClass<*>,
267         concreteClass: KClass<*>
268     ) : this("Serializer for $concreteClass already registered in the scope of $baseClass")
269 }
270