chore(TypeHandlerLibrary)! make Serializer more type-safe

Author: keturn

engine/src/main/java/org/terasology/engine/entitySystem/metadata/EventLibrary.java

@@ -1,4 +1,4 @@
-// Copyright 2021 The Terasology Foundation
+// Copyright 2022 The Terasology Foundation
 // SPDX-License-Identifier: Apache-2.0
 package org.terasology.engine.entitySystem.metadata;
 
@@ -49,7 +49,6 @@ public <T extends Event> EventMetadata<T> getMetadata(T object) {
     }
 
     @Override
-    @SuppressWarnings("unchecked")
     public EventMetadata<? extends Event> getMetadata(ResourceUrn uri) {
         return (EventMetadata<? extends Event>) super.getMetadata(uri);
     }

engine/src/main/java/org/terasology/engine/persistence/serializers/ComponentSerializer.java

@@ -1,4 +1,4 @@
-// Copyright 2021 The Terasology Foundation
+// Copyright 2022 The Terasology Foundation
 // SPDX-License-Identifier: Apache-2.0
 
 package org.terasology.engine.persistence.serializers;
@@ -61,31 +61,29 @@ public void removeIdMapping() {
     }
 
     /**
-     * @param eventData
      * @return The event described by the eventData
-     * @throws org.terasology.engine.persistence.typeHandling.DeserializationException if an error occurs when deserializing
+     * @throws org.terasology.persistence.typeHandling.DeserializationException if an error occurs when deserializing
      */
     public Event deserialize(EntityData.Event eventData) {
-        Class<? extends Event> eventClass = getEventClass(eventData);
+        var eventClass = getEventClass(eventData);
         if (eventClass != null) {
-            EventMetadata<?> eventMetadata = eventLibrary.getMetadata(eventClass);
+            var eventMetadata = eventLibrary.getMetadata(eventClass);
             if (!eventMetadata.isConstructable()) {
                 throw new DeserializationException("Cannot deserialize " + eventMetadata + " - lacks default constructor");
             } else {
-                Event event = eventMetadata.newInstance();
-                return deserializeOnto(event, eventData, eventMetadata);
+                return deserializeOnto(eventMetadata.newInstance(), eventData, eventMetadata);
             }
         } else {
             throw new DeserializationException("Unable to deserialize unknown event type: " + eventData.getType());
         }
     }
 
 
-    private Event deserializeOnto(Event targetEvent, EntityData.Event eventData, EventMetadata<? extends Event> eventMetadata) {
-        Serializer serializer = typeHandlerLibrary.getSerializerFor(eventMetadata);
+    private <C extends Event> Event deserializeOnto(C targetEvent, EntityData.Event eventData, EventMetadata<C> eventMetadata) {
+        Serializer<C> serializer = typeHandlerLibrary.getSerializerFor(eventMetadata);
         for (int i = 0; i < eventData.getFieldIds().size(); ++i) {
             byte fieldId = eventData.getFieldIds().byteAt(i);
-            ReplicatedFieldMetadata<?, ?> fieldInfo = eventMetadata.getField(fieldId);
+            var fieldInfo = eventMetadata.getField(fieldId);
             if (fieldInfo == null) {
                 logger.error("Unable to serialize field {}, out of bounds", fieldId);
                 continue;
@@ -100,12 +98,11 @@ private Event deserializeOnto(Event targetEvent, EntityData.Event eventData, Eve
     /**
      * Serializes an event.
      *
-     * @param event
      * @return The serialized event
-     * @throws org.terasology.engine.persistence.typeHandling.SerializationException if an error occurs during serialization
+     * @throws org.terasology.persistence.typeHandling.SerializationException if an error occurs during serialization
      */
-    public EntityData.Event serialize(Event event) {
-        EventMetadata<?> eventMetadata = eventLibrary.getMetadata(event.getClass());
+    public <E extends Event> EntityData.Event serialize(E event) {
+        @SuppressWarnings("unchecked") var eventMetadata = eventLibrary.getMetadata((Class<E>) event.getClass());
         if (eventMetadata == null) {
             throw new SerializationException("Unregistered event type: " + event.getClass());
         } else if (!eventMetadata.isConstructable()) {
@@ -115,19 +112,19 @@ public EntityData.Event serialize(Event event) {
         EntityData.Event.Builder eventData = EntityData.Event.newBuilder();
         serializeEventType(event, eventData);
 
-        Serializer eventSerializer = typeHandlerLibrary.getSerializerFor(eventMetadata);
+        Serializer<E> eventSerializer = typeHandlerLibrary.getSerializerFor(eventMetadata);
         ByteString.Output fieldIds = ByteString.newOutput();
-        for (ReplicatedFieldMetadata field : eventMetadata.getFields()) {
-            if (field.isReplicated()) {
-                EntityData.Value serializedValue = ((ProtobufPersistedData) eventSerializer
-                        .serialize(field, event, persistedDataSerializer))
-                        .getValue();
-                if (serializedValue != null) {
-                    eventData.addFieldValue(serializedValue);
-                    fieldIds.write(field.getId());
-                }
+        eventMetadata.getFields().stream()
+                .filter(ReplicatedFieldMetadata::isReplicated)
+                .forEach(field -> {
+            EntityData.Value serializedValue = ((ProtobufPersistedData) eventSerializer
+                    .serialize(field, event, persistedDataSerializer))
+                    .getValue();
+            if (serializedValue != null) {
+                eventData.addFieldValue(serializedValue);
+                fieldIds.write(field.getId());
             }
-        }
+        });
         eventData.setFieldIds(fieldIds.toByteString());
 
         return eventData.build();
@@ -141,16 +138,16 @@ private void serializeEventType(Event event, EntityData.Event.Builder eventData)
     /**
      * Determines the event class that the serialized event is for.
      *
-     * @param eventData
      * @return The event class the given eventData describes, or null if it is unknown.
      */
-    public Class<? extends Event> getEventClass(EntityData.Event eventData) {
+    public <E extends Event> Class<E> getEventClass(EntityData.Event eventData) {
         if (eventData.hasType()) {
-            EventMetadata<? extends Event> metadata = null;
+            EventMetadata<E> metadata = null;
             if (!idTable.isEmpty()) {
-                Class<? extends Event> eventClass = idTable.inverse().get(eventData.getType());
+                var eventClass = idTable.inverse().get(eventData.getType());
                 if (eventClass != null) {
-                    metadata = eventLibrary.getMetadata(eventClass);
+                    //noinspection unchecked
+                    metadata = (EventMetadata<E>) eventLibrary.getMetadata(eventClass);
                 }
             }
             if (metadata == null) {

engine/src/main/java/org/terasology/engine/persistence/serializers/EventSerializer.java

@@ -13,26 +13,13 @@ group = "org.terasology.subsystems"
 version = project(":engine").version
 
 dependencies {
-    implementation("org.slf4j:slf4j-api:1.7.32")
+    implementation("org.slf4j:slf4j-api:1.7.36")
     implementation("net.sf.trove4j:trove4j:3.0.3")
 
     implementation("org.terasology:reflections:0.9.12-MB")
     implementation("org.terasology.nui:nui-reflect:3.0.0")
     implementation("org.terasology.gestalt:gestalt-module:7.1.0")
     implementation("org.terasology.gestalt:gestalt-asset-core:7.1.0")
-
-    testRuntimeOnly("org.slf4j:slf4j-simple:1.7.32") {
-        because("log output during tests")
-    }
-    testImplementation(platform("org.junit:junit-bom:5.8.1")) {
-        // junit-bom will set version numbers for the other org.junit dependencies.
-    }
-    testImplementation("org.junit.jupiter:junit-jupiter-api")
-    testImplementation("org.junit.jupiter:junit-jupiter-params")
-    testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine")
-    testImplementation("org.mockito:mockito-inline:3.12.4")
-
-    testImplementation("org.mockito:mockito-junit-jupiter:3.12.4")
 }
 
 tasks.register<Test>("unitTest") {

subsystems/TypeHandlerLibrary/build.gradle.kts

@@ -1,4 +1,4 @@
-// Copyright 2021 The Terasology Foundation
+// Copyright 2022 The Terasology Foundation
 // SPDX-License-Identifier: Apache-2.0
 package org.terasology.persistence.typeHandling;
 
@@ -14,14 +14,14 @@
  * A serializer provides low-level serialization support for a type, using a mapping of type handlers for each field of that type.
  *
  */
-public class Serializer {
+public class Serializer<C> {
 
     private static final Logger logger = LoggerFactory.getLogger(Serializer.class);
 
-    private ClassMetadata<?, ?> classMetadata;
-    private Map<FieldMetadata<?, ?>, TypeHandler> fieldHandlers;
+    private final ClassMetadata<C, ?> classMetadata;
+    private final Map<FieldMetadata<C, ?>, TypeHandler<?>> fieldHandlers;
 
-    public Serializer(ClassMetadata<?, ?> classMetadata, Map<FieldMetadata<?, ?>, TypeHandler> fieldHandlers) {
+    public Serializer(ClassMetadata<C, ? extends FieldMetadata<C, ?>> classMetadata, Map<FieldMetadata<C, ?>, TypeHandler<?>> fieldHandlers) {
         this.fieldHandlers = fieldHandlers;
         this.classMetadata = classMetadata;
     }
@@ -30,8 +30,8 @@ public Serializer(ClassMetadata<?, ?> classMetadata, Map<FieldMetadata<?, ?>, Ty
      * @param field The metadata for a field of the type handled by this serializer.
      * @return The TypeHandler for the given field
      */
-    public TypeHandler<?> getHandlerFor(FieldMetadata<?, ?> field) {
-        return fieldHandlers.get(field);
+    public <F> TypeHandler<F> getHandlerFor(FieldMetadata<C, F> field) {
+        return (TypeHandler<F>) fieldHandlers.get(field);
     }
 
     /**
@@ -42,11 +42,10 @@ public TypeHandler<?> getHandlerFor(FieldMetadata<?, ?> field) {
      * @param context   The current serialization context
      * @return The serialized value of the field
      */
-    @SuppressWarnings("unchecked")
-    public PersistedData serialize(FieldMetadata<?, ?> field, Object container, PersistedDataSerializer context) {
-        Object rawValue = field.getValue(container);
+    public <F> PersistedData serialize(FieldMetadata<C, F> field, C container, PersistedDataSerializer context) {
+        F rawValue = field.getValue(container);
         if (rawValue != null) {
-            TypeHandler handler = getHandlerFor(field);
+            TypeHandler<F> handler = getHandlerFor(field);
             if (handler != null) {
                 return handler.serialize(rawValue, context);
             }
@@ -62,9 +61,9 @@ public PersistedData serialize(FieldMetadata<?, ?> field, Object container, Pers
      * @param rawValue The value to serialize
      * @return The serialized value
      */
-    @SuppressWarnings("unchecked")
-    public PersistedData serializeValue(FieldMetadata<?, ?> fieldMetadata, Object rawValue, PersistedDataSerializer context) {
-        return fieldHandlers.get(fieldMetadata).serialize(rawValue, context);
+    public <F> PersistedData serializeValue(FieldMetadata<C, F> fieldMetadata, F rawValue, PersistedDataSerializer context) {
+        @SuppressWarnings("unchecked") TypeHandler<F> handler = (TypeHandler<F>) fieldHandlers.get(fieldMetadata);
+        return handler.serialize(rawValue, context);
     }
 
     /**
@@ -74,13 +73,13 @@ public PersistedData serializeValue(FieldMetadata<?, ?> fieldMetadata, Object ra
      * @param fieldMetadata The metadata of the field
      * @param data          The serialized value of the field
      */
-    public void deserializeOnto(Object target, FieldMetadata<?, ?> fieldMetadata, PersistedData data) {
-        TypeHandler<?> handler = getHandlerFor(fieldMetadata);
+    public <F> void deserializeOnto(C target, FieldMetadata<C, F> fieldMetadata, PersistedData data) {
+        TypeHandler<F> handler = getHandlerFor(fieldMetadata);
         if (handler == null) {
             logger.error("No type handler for type {} used by {}::{}", fieldMetadata.getType(), target.getClass(), fieldMetadata);
         } else {
             try {
-                Object deserializedValue = handler.deserializeOrNull(data);
+                F deserializedValue = handler.deserializeOrNull(data);
                 fieldMetadata.setValue(target, deserializedValue);
             } catch (DeserializationException e) {
                 logger.error("Unable to deserialize field '{}' from '{}'", fieldMetadata.getName(), data.toString(), e);
@@ -94,7 +93,7 @@ public void deserializeOnto(Object target, FieldMetadata<?, ?> fieldMetadata, Pe
      * @param target  The object to deserialize onto
      * @param values  The collection of values to apply to the object
      */
-    public void deserializeOnto(Object target, PersistedDataMap values) {
+    public void deserializeOnto(C target, PersistedDataMap values) {
         deserializeOnto(target, values, DeserializeFieldCheck.NullCheck.newInstance());
     }
 
@@ -105,15 +104,16 @@ public void deserializeOnto(Object target, PersistedDataMap values) {
      * @param values The collection of values to apply to the object
      * @param check  A check to filter which fields to deserialize
      */
-    public void deserializeOnto(Object target, PersistedDataMap values, DeserializeFieldCheck check) {
-        for (Map.Entry<String, PersistedData> field : values.entrySet()) {
-            FieldMetadata<?, ?> fieldInfo = classMetadata.getField(field.getKey());
-
-            if (fieldInfo != null && check.shouldDeserialize(classMetadata, fieldInfo)) {
-                deserializeOnto(target, fieldInfo, field.getValue());
-            } else if (fieldInfo == null) {
-                logger.warn("Cannot deserialize unknown field '{}' onto '{}'", field.getKey(), classMetadata.getId());
-            }
+    public void deserializeOnto(C target, PersistedDataMap values, DeserializeFieldCheck check) {
+        values.entrySet().forEach(field -> goomp(target, check, field.getKey(), field.getValue()));
+    }
+
+    private void goomp(C target, DeserializeFieldCheck check, String fieldName, PersistedData data) {
+        var fieldInfo = classMetadata.getField(fieldName);
+        if (fieldInfo != null && check.shouldDeserialize(classMetadata, fieldInfo)) {
+            deserializeOnto(target, fieldInfo, data);
+        } else if (fieldInfo == null) {
+            logger.warn("Cannot deserialize unknown field '{}' onto '{}'", fieldName, classMetadata.getId());
         }
     }
 
@@ -123,7 +123,7 @@ public void deserializeOnto(Object target, PersistedDataMap values, DeserializeF
      * @param target The object to deserialize onto
      * @param values The collection of values to apply to the object
      */
-    public void deserializeOnto(Object target, Map<FieldMetadata<?, ?>, PersistedData> values) {
+    public void deserializeOnto(C target, Map<FieldMetadata<C, ?>, PersistedData> values) {
         deserializeOnto(target, values, DeserializeFieldCheck.NullCheck.newInstance());
     }
 
@@ -134,12 +134,12 @@ public void deserializeOnto(Object target, Map<FieldMetadata<?, ?>, PersistedDat
      * @param values The collection of values to apply to the object
      * @param check  A check to filter which fields to deserialize
      */
-    public void deserializeOnto(Object target, Map<FieldMetadata<?, ?>, PersistedData> values, DeserializeFieldCheck check) {
-        for (Map.Entry<FieldMetadata<?, ?>, PersistedData> field : values.entrySet()) {
-            if (check.shouldDeserialize(classMetadata, field.getKey())) {
-                deserializeOnto(target, field.getKey(), field.getValue());
+    public void deserializeOnto(C target, Map<FieldMetadata<C, ?>, PersistedData> values, DeserializeFieldCheck check) {
+        values.forEach((field, data) -> {
+            if (check.shouldDeserialize(classMetadata, field)) {
+                deserializeOnto(target, field, data);
             }
-        }
+        });
     }
 
 

subsystems/TypeHandlerLibrary/src/main/java/org/terasology/persistence/typeHandling/Serializer.java

@@ -1,4 +1,4 @@
-// Copyright 2021 The Terasology Foundation
+// Copyright 2022 The Terasology Foundation
 // SPDX-License-Identifier: Apache-2.0
 
 package org.terasology.persistence.typeHandling;
@@ -57,14 +57,14 @@ public class TypeHandlerLibrary {
     private final List<TypeHandlerFactory> typeHandlerFactories = Lists.newArrayList();
     private final Map<Type, InstanceCreator<?>> instanceCreators = Maps.newHashMap();
     private final Map<TypeInfo<?>, TypeHandler<?>> typeHandlerCache = Maps.newHashMap();
-    private final Map<ClassMetadata<?, ?>, Serializer> serializerMap = Maps.newHashMap();
+    private final Map<ClassMetadata<?, ?>, Serializer<?>> serializerMap = Maps.newHashMap();
 
     protected TypeHandlerLibrary(SerializationSandbox sandbox) {
         this.sandbox = sandbox;
         ConstructorLibrary constructorLibrary = new ConstructorLibrary(instanceCreators);
         addTypeHandlerFactory(new ObjectFieldMapTypeHandlerFactory(constructorLibrary));
         TypeHandlerLibrary.populateBuiltInHandlers(this);
-        addTypeHandlerFactory(new CollectionTypeHandlerFactory(constructorLibrary));
+        addTypeHandlerFactory(new CollectionTypeHandlerFactory());
     }
 
     public TypeHandlerLibrary(Reflections reflections) {
@@ -122,11 +122,11 @@ public TypeHandlerLibrary copy() {
      * @param type The ClassMetadata for the type of interest
      * @return A serializer for serializing/deserializing the type
      */
-    public Serializer getSerializerFor(ClassMetadata<?, ?> type) {
-        Serializer serializer = serializerMap.get(type);
+    public <C> Serializer<C> getSerializerFor(ClassMetadata<C, ? extends FieldMetadata<C, ?>> type) {
+        @SuppressWarnings("unchecked") Serializer<C> serializer = (Serializer<C>) serializerMap.get(type);
         if (serializer == null) {
-            Map<FieldMetadata<?, ?>, TypeHandler> fieldHandlerMap = getFieldHandlerMap(type);
-            serializer = new Serializer(type, fieldHandlerMap);
+            var fieldHandlerMap = getFieldHandlerMap(type);
+            serializer = new Serializer<>(type, fieldHandlerMap);
             serializerMap.put(type, serializer);
         }
         return serializer;
@@ -209,10 +209,9 @@ public <T> void addInstanceCreator(TypeInfo<T> typeInfo, InstanceCreator<T> inst
      * @param type The {@link Type} describing the type for which to retrieve the {@link TypeHandler}.
      * @return The {@link TypeHandler} for the specified type, if available.
      */
-    @SuppressWarnings("unchecked")
-    public Optional<TypeHandler<?>> getTypeHandler(Type type) {
-        TypeInfo typeInfo = TypeInfo.of(type);
-        return (Optional<TypeHandler<?>>) getTypeHandler(typeInfo);
+    public <T> Optional<TypeHandler<T>> getTypeHandler(Type type) {
+        TypeInfo<T> typeInfo = TypeInfo.of(type);
+        return getTypeHandler(typeInfo);
     }
 
     /**
@@ -310,17 +309,17 @@ public <T> TypeHandler<T> getBaseTypeHandler(TypeInfo<T> typeInfo) {
         return new RuntimeDelegatingTypeHandler<>(delegateHandler, typeInfo, context);
     }
 
-    private Map<FieldMetadata<?, ?>, TypeHandler> getFieldHandlerMap(ClassMetadata<?, ?> type) {
-        Map<FieldMetadata<?, ?>, TypeHandler> handlerMap = Maps.newHashMap();
-        for (FieldMetadata<?, ?> field : type.getFields()) {
-            Optional<TypeHandler<?>> handler = getTypeHandler(field.getField().getGenericType());
-
-            if (handler.isPresent()) {
-                handlerMap.put(field, handler.get());
-            } else {
-                logger.error("Unsupported field: '{}.{}'", type.getId(), field.getName());
-            }
-        }
+    private <C> Map<FieldMetadata<C, ?>, TypeHandler<?>> getFieldHandlerMap(ClassMetadata<C, ? extends FieldMetadata<C, ?>> type) {
+        Map<FieldMetadata<C, ?>, TypeHandler<?>> handlerMap = new HashMap<>();
+        type.getFields().forEach(field ->
+            getFmConsumer(field).ifPresentOrElse(
+                handler -> handlerMap.put(field, handler),
+                () -> logger.error("Unsupported field: '{}.{}'", type.getId(), field.getName())
+        ));
         return handlerMap;
     }
+
+    private <T> Optional<TypeHandler<T>> getFmConsumer(FieldMetadata<?, T> field) {
+        return getTypeHandler(field.getField().getGenericType());
+    }
 }

subsystems/TypeHandlerLibrary/src/main/java/org/terasology/persistence/typeHandling/TypeHandlerLibrary.java

@@ -64,7 +64,7 @@ public PersistedData serializeNonNull(T value, PersistedDataSerializer serialize
         Type runtimeType = getRuntimeTypeIfMoreSpecific(value);
 
         if (!typeInfo.getType().equals(runtimeType)) {
-            Optional<TypeHandler<?>> runtimeTypeHandler = typeHandlerLibrary.getTypeHandler(runtimeType);
+            var runtimeTypeHandler = typeHandlerLibrary.getTypeHandler(runtimeType);
 
             chosenHandler =
                 (TypeHandler<T>)