add Gson type adapters

[Closes #3]

Author: fprochazka

gradle/libs.versions.toml

@@ -10,6 +10,7 @@ uuidGenerator = { module = "com.fasterxml.uuid:java-uuid-generator", version = "
 jetbrains-annotations = { module = "org.jetbrains:annotations", version = "26.0.2" }
 jackson-databind = { group = "com.fasterxml.jackson.core", name = "jackson-databind", version.ref = "jackson" }
 jackson-annotations = { group = "com.fasterxml.jackson.core", name = "jackson-annotations", version.ref = "jackson" }
+gson = { module = "com.google.code.gson:gson", version = "2.10.1" }
 autoService-processor = { group = "com.google.auto.service", name = "auto-service", version.ref = "googleAutoService" }
 autoService-annotations = { group = "com.google.auto.service", name = "auto-service-annotations", version.ref = "googleAutoService" }
 errorprone-annotations = { group = "com.google.errorprone", name = "error_prone_annotations", version.ref = "errorProne" }

modules/typed-ids/build.gradle.kts

@@ -14,10 +14,12 @@ dependencies {
     annotationProcessor(libs.autoService.processor)
 
     compileOnly(libs.jackson.databind)
+    compileOnly(libs.gson)
     compileOnly(libs.kotlinx.serialization)
 
     testImplementation(project(":typed-ids-testing"))
     testImplementation(libs.jackson.databind)
+    testImplementation(libs.gson)
     testImplementation(libs.kotlinx.serialization)
     testRuntimeOnly("org.junit.platform:junit-platform-launcher")
 }

modules/typed-ids/src/main/java/org/framefork/typedIds/bigint/json/gson/ObjectBigIntIdTypeAdapter.java

@@ -0,0 +1,41 @@
+package org.framefork.typedIds.bigint.json.gson;
+
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import org.framefork.typedIds.bigint.ObjectBigIntId;
+import org.framefork.typedIds.bigint.ObjectBigIntIdTypeUtils;
+import org.framefork.typedIds.common.ReflectionHacks;
+
+import java.io.IOException;
+import java.lang.invoke.MethodHandle;
+
+public class ObjectBigIntIdTypeAdapter<T extends ObjectBigIntId<T>> extends TypeAdapter<T>
+{
+
+    private final MethodHandle constructor;
+
+    public ObjectBigIntIdTypeAdapter(final Class<T> identifierClass)
+    {
+        if (!ObjectBigIntId.class.isAssignableFrom(identifierClass)) {
+            throw new IllegalArgumentException("Type %s is not a subtype of %s".formatted(identifierClass, ObjectBigIntId.class));
+        }
+
+        this.constructor = ReflectionHacks.getMainConstructor(identifierClass, long.class);
+    }
+
+    @Override
+    public void write(final JsonWriter writer, final T value) throws IOException
+    {
+        writer.jsonValue(String.valueOf(value.toLong()));
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public T read(final JsonReader in) throws IOException
+    {
+        var raw = in.nextLong();
+        return (T) ObjectBigIntIdTypeUtils.wrapBigIntToIdentifier(raw, constructor);
+    }
+
+}

modules/typed-ids/src/main/java/org/framefork/typedIds/bigint/json/gson/ObjectBigIntIdTypeAdapterFactory.java

@@ -0,0 +1,34 @@
+package org.framefork.typedIds.bigint.json.gson;
+
+import com.google.auto.service.AutoService;
+import com.google.gson.Gson;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+import org.framefork.typedIds.bigint.ObjectBigIntId;
+import org.framefork.typedIds.bigint.ObjectBigIntIdTypeUtils;
+import org.jspecify.annotations.Nullable;
+
+@SuppressWarnings("unchecked")
+@AutoService(TypeAdapterFactory.class)
+public class ObjectBigIntIdTypeAdapterFactory implements TypeAdapterFactory
+{
+
+    @Nullable
+    @Override
+    public <T> TypeAdapter<T> create(final Gson gson, final TypeToken<T> typeToken)
+    {
+        var rawType = (Class<T>) typeToken.getRawType();
+        if (!ObjectBigIntIdTypeUtils.getObjectBigIntIdRawClass().isAssignableFrom(rawType)) {
+            return null;
+        }
+
+        return (TypeAdapter<T>) casted(rawType);
+    }
+
+    private static <T extends ObjectBigIntId<T>> ObjectBigIntIdTypeAdapter<?> casted(final Class<?> rawType)
+    {
+        return new ObjectBigIntIdTypeAdapter<>((Class<T>) rawType);
+    }
+
+}

modules/typed-ids/src/main/java/org/framefork/typedIds/uuid/json/gson/ObjectUuidTypeAdapter.java

@@ -0,0 +1,42 @@
+package org.framefork.typedIds.uuid.json.gson;
+
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import org.framefork.typedIds.common.ReflectionHacks;
+import org.framefork.typedIds.uuid.ObjectUuid;
+import org.framefork.typedIds.uuid.ObjectUuidTypeUtils;
+
+import java.io.IOException;
+import java.lang.invoke.MethodHandle;
+import java.util.UUID;
+
+public class ObjectUuidTypeAdapter<T extends ObjectUuid<T>> extends TypeAdapter<T>
+{
+
+    private final MethodHandle constructor;
+
+    public ObjectUuidTypeAdapter(final Class<T> identifierClass)
+    {
+        if (!ObjectUuid.class.isAssignableFrom(identifierClass)) {
+            throw new IllegalArgumentException("Type %s is not a subtype of %s".formatted(identifierClass, ObjectUuid.class));
+        }
+
+        this.constructor = ReflectionHacks.getMainConstructor(identifierClass, UUID.class);
+    }
+
+    @Override
+    public void write(final JsonWriter writer, final T value) throws IOException
+    {
+        writer.value(value.toNativeUuid().toString());
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public T read(final JsonReader in) throws IOException
+    {
+        var uuid = UUID.fromString(in.nextString());
+        return (T) ObjectUuidTypeUtils.wrapUuidToIdentifier(uuid, constructor);
+    }
+
+}

modules/typed-ids/src/main/java/org/framefork/typedIds/uuid/json/gson/ObjectUuidTypeAdapterFactory.java

@@ -0,0 +1,34 @@
+package org.framefork.typedIds.uuid.json.gson;
+
+import com.google.auto.service.AutoService;
+import com.google.gson.Gson;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+import org.framefork.typedIds.uuid.ObjectUuid;
+import org.framefork.typedIds.uuid.ObjectUuidTypeUtils;
+import org.jspecify.annotations.Nullable;
+
+@SuppressWarnings("unchecked")
+@AutoService(TypeAdapterFactory.class)
+public class ObjectUuidTypeAdapterFactory implements TypeAdapterFactory
+{
+
+    @Nullable
+    @Override
+    public <T> TypeAdapter<T> create(final Gson gson, final TypeToken<T> typeToken)
+    {
+        var rawType = (Class<T>) typeToken.getRawType();
+        if (!ObjectUuidTypeUtils.getObjectUuidRawClass().isAssignableFrom(rawType)) {
+            return null;
+        }
+
+        return (TypeAdapter<T>) casted(rawType);
+    }
+
+    private static <T extends ObjectUuid<T>> ObjectUuidTypeAdapter<?> casted(final Class<?> rawType)
+    {
+        return new ObjectUuidTypeAdapter<>((Class<T>) rawType);
+    }
+
+}

modules/typed-ids/src/test/java/org/framefork/typedIds/bigint/json/gson/ObjectBigIntIdGsonTest.java

@@ -0,0 +1,35 @@
+package org.framefork.typedIds.bigint.json.gson;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import org.framefork.typedIds.bigint.ObjectBigIntIdMock;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class ObjectBigIntIdGsonTest
+{
+
+    private final Gson gson = new GsonBuilder()
+        .registerTypeAdapterFactory(new ObjectBigIntIdTypeAdapterFactory())
+        .create();
+
+    @Test
+    public void functional() throws Exception
+    {
+        var id42 = ObjectBigIntIdMock.from("42");
+        var originalDto = new Dto(id42);
+
+        var dtoJson = gson.toJson(originalDto);
+        assertThat(dtoJson).isEqualTo("{\"id\":42}");
+
+        var deserializedDto = gson.fromJson(dtoJson, Dto.class);
+        assertThat(deserializedDto).isEqualTo(originalDto);
+    }
+
+    record Dto(ObjectBigIntIdMock id)
+    {
+
+    }
+
+}

modules/typed-ids/src/test/java/org/framefork/typedIds/uuid/json/gson/ObjectUuidGsonTest.java

@@ -0,0 +1,35 @@
+package org.framefork.typedIds.uuid.json.gson;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import org.framefork.typedIds.uuid.ObjectUuidMock;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class ObjectUuidGsonTest
+{
+
+    private final Gson gson = new GsonBuilder()
+        .registerTypeAdapterFactory(new ObjectUuidTypeAdapterFactory())
+        .create();
+
+    @Test
+    public void functional() throws Exception
+    {
+        var id33 = ObjectUuidMock.from("33a7641c-811e-40b7-986e-ad109cfcf220");
+        var originalDto = new Dto(id33);
+
+        var dtoJson = gson.toJson(originalDto);
+        assertThat(dtoJson).isEqualTo("{\"id\":\"33a7641c-811e-40b7-986e-ad109cfcf220\"}");
+
+        var deserializedDto = gson.fromJson(dtoJson, Dto.class);
+        assertThat(deserializedDto).isEqualTo(originalDto);
+    }
+
+    record Dto(ObjectUuidMock id)
+    {
+
+    }
+
+}