feat(extract-subsystems): extract Context, @In, InjectionHelper and @Share to Subsystem

engine/build.gradle

@@ -148,6 +148,7 @@ dependencies {
     implementation group: 'org.terasology.crashreporter', name: 'cr-terasology', version: '4.2.0'
 
     api(project(":subsystems:TypeHandlerLibrary"))
+    api(project(":subsystems:Context"))
 }
 
 protobuf {

subsystems/Context/README.MD

@@ -0,0 +1,21 @@
+# Context
+
+>It is really not subsystem. but used by them
+
+Context is simple DI implementation for TS
+
+Provide interface for working with context. 
+
+## How to use (from scratch, not Terasology)
+
+1. Implement `Context` class
+2. Create it
+3. Provide it.
+4. Use `InjectionHelper` with context to inject at `@In` fields
+
+## How to use (with Terasology)
+
+1. Create your system/manager/another injectable class type
+2. Write field with `@In` - be sure that Field Type is injectable. then Field will be injected
+with manager/system/ another injectable class type
+3. Mark with `@Share` - be sure that your class is injectable type. then your class be provided to `Context`.

subsystems/Context/build.gradle.kts

@@ -0,0 +1,19 @@
+// Copyright 2021 The Terasology Foundation
+// SPDX-License-Identifier: Apache-2.0
+
+plugins {
+    java
+    `java-library`
+}
+
+apply(from = "$rootDir/config/gradle/common.gradle")
+
+dependencies {
+    implementation("org.terasology.gestalt:gestalt-util:7.2.0-SNAPSHOT")
+    implementation("org.terasology.gestalt:gestalt-module:7.2.0-SNAPSHOT")
+
+    implementation("ch.qos.logback:logback-classic:1.2.3")
+
+    testImplementation("org.junit.jupiter:junit-jupiter-api:5.5.2")
+    testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine:5.5.2")
+}

engine/src/main/java/org/terasology/engine/registry/InjectionHelper.java → subsystems/Context/src/main/java/org/terasology/engine/registry/InjectionHelper.java

@@ -2,7 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 package org.terasology.engine.registry;
 
-import org.reflections.ReflectionUtils;
+import com.google.common.collect.Sets;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.terasology.engine.context.Context;
@@ -16,6 +16,7 @@
 import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.Optional;
+import java.util.Set;
 
 public final class InjectionHelper {
     private static final Logger logger = LoggerFactory.getLogger(InjectionHelper.class);
@@ -25,7 +26,7 @@ private InjectionHelper() {
 
     public static void inject(final Object object, Context context) {
         AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
-            for (Field field : ReflectionUtils.getAllFields(object.getClass(), ReflectionUtils.withAnnotation(In.class))) {
+            for (Field field : getAllFields(object.getClass(), In.class)) {
                 Object value = context.get(field.getType());
                 if (value != null) {
                     try {
@@ -43,7 +44,7 @@ public static void inject(final Object object, Context context) {
 
     public static void inject(final Object object) {
         AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
-            for (Field field : ReflectionUtils.getAllFields(object.getClass(), ReflectionUtils.withAnnotation(In.class))) {
+            for (Field field : getAllFields(object.getClass(), In.class)) {
                 Object value = CoreRegistry.get(field.getType());
                 if (value != null) {
                     try {
@@ -64,7 +65,7 @@ public static void inject(final Object object) {
 
     public static <T> void inject(final Object object, final Class<? extends Annotation> annotation, final Map<Class<? extends T>, T> source) {
         AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
-            for (Field field : ReflectionUtils.getAllFields(object.getClass(), ReflectionUtils.withAnnotation(annotation))) {
+            for (Field field : getAllFields(object.getClass(), annotation)) {
                 Object value = source.get(field.getType());
                 if (value != null) {
                     try {
@@ -82,6 +83,20 @@ public static <T> void inject(final Object object, final Class<? extends Annotat
         });
     }
 
+    private static Set<Field> getAllFields(Class<?> clazz, Class<? extends Annotation> annotation) {
+        Set<Field> result = Sets.newLinkedHashSet();
+        Class<?> candidate = clazz;
+        while (candidate != null) {
+            for (Field field : candidate.getDeclaredFields()) {
+                if (field.getAnnotation(annotation) != null) {
+                    result.add(field);
+                }
+            }
+            candidate = candidate.getSuperclass();
+        }
+        return result;
+    }
+
     public static void share(Object object) {
         Share share = object.getClass().getAnnotation(Share.class);
         if (share != null && share.value() != null) {

subsystems/Context/src/test/java/org/terasology/engine/registry/ContextImplementation.java

@@ -0,0 +1,27 @@
+// Copyright 2021 The Terasology Foundation
+// SPDX-License-Identifier: Apache-2.0
+
+package org.terasology.engine.registry;
+
+import com.google.common.collect.Maps;
+import org.terasology.engine.context.Context;
+
+import java.util.Map;
+
+public class ContextImplementation implements Context {
+    private final Map<Class<?>, Object> map = Maps.newConcurrentMap();
+
+    @Override
+    public <T> T get(Class<? extends T> type) {
+        T result = type.cast(map.get(type));
+        if (result != null) {
+            return result;
+        }
+        return null;
+    }
+
+    @Override
+    public <T, U extends T> void put(Class<T> type, U object) {
+        map.put(type, object);
+    }
+}

engine-tests/src/test/java/org/terasology/engine/registry/CoreRegistryTest.java → subsystems/Context/src/test/java/org/terasology/engine/registry/CoreRegistryTest.java

@@ -3,16 +3,11 @@
 
 package org.terasology.engine.registry;
 
-import com.google.common.collect.Maps;
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.terasology.engine.context.Context;
 
-import java.util.Map;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNotEquals;
-
 public class CoreRegistryTest {
     private Context context;
 
@@ -31,7 +26,7 @@ public void setup() {
     @Test
     public void testContextChange() {
         CoreRegistry.setContext(new ContextImplementation());
-        assertNotEquals(CoreRegistry.get(Context.class), context);
+        Assertions.assertNotEquals(CoreRegistry.get(Context.class), context);
     }
 
     /**
@@ -41,8 +36,8 @@ public void testContextChange() {
     public void testNullReturnOnMissingContext() {
         CoreRegistry.setContext(null);
 
-        assertEquals(CoreRegistry.put(Integer.class, 10), null);
-        assertEquals(CoreRegistry.get(Integer.class), null);
+        Assertions.assertEquals(CoreRegistry.put(Integer.class, 10), null);
+        Assertions.assertEquals(CoreRegistry.get(Integer.class), null);
     }
 
     /**
@@ -51,9 +46,9 @@ public void testNullReturnOnMissingContext() {
      */
     @Test
     public void testContextGetIndependenceFromContextInterfaceImplementation() {
-        assertEquals(CoreRegistry.get(Context.class), context);
+        Assertions.assertEquals(CoreRegistry.get(Context.class), context);
 
-        assertEquals(context.get(Context.class), null);
+        Assertions.assertEquals(context.get(Context.class), null);
     }
 
     /**
@@ -64,35 +59,18 @@ public void testContextMethodsCalled() {
         // Load value in context
         Integer value = 10;
         CoreRegistry.put(Integer.class, value);
-        assertEquals(value, context.get(Integer.class));
-        assertEquals(context.get(Integer.class), CoreRegistry.get(Integer.class));
+        Assertions.assertEquals(value, context.get(Integer.class));
+        Assertions.assertEquals(context.get(Integer.class), CoreRegistry.get(Integer.class));
 
         // Change context
         CoreRegistry.setContext(new ContextImplementation());
-        assertNotEquals(CoreRegistry.get(Context.class), context);
-        assertEquals(CoreRegistry.get(Integer.class), null);
+        Assertions.assertNotEquals(CoreRegistry.get(Context.class), context);
+        Assertions.assertEquals(CoreRegistry.get(Integer.class), null);
 
         // Restore first context
         CoreRegistry.setContext(context);
-        assertEquals(CoreRegistry.get(Integer.class), value);
+        Assertions.assertEquals(CoreRegistry.get(Integer.class), value);
     }
 
 
-    private static class ContextImplementation implements Context {
-        private final Map<Class<?>, Object> map = Maps.newConcurrentMap();
-
-        @Override
-        public <T> T get(Class<? extends T> type) {
-            T result = type.cast(map.get(type));
-            if (result != null) {
-                return result;
-            }
-            return null;
-        }
-
-        @Override
-        public <T, U extends T> void put(Class<T> type, U object) {
-            map.put(type, object);
-        }
-    }
 }

engine-tests/src/test/java/org/terasology/engine/registry/InjectionHelperTest.java → subsystems/Context/src/test/java/org/terasology/engine/registry/InjectionHelperTest.java

@@ -6,13 +6,9 @@
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.terasology.engine.context.Context;
-import org.terasology.engine.context.internal.ContextImpl;
 
 import java.util.NoSuchElementException;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNull;
-
 public class InjectionHelperTest {
 
     private ServiceA serviceA;
@@ -24,23 +20,23 @@ public void setUp() {
         serviceB = new ServiceBImpl();
         //injection helper uses the core registry, 
         //make sure the shared classes are not used over multiple tests
-        CoreRegistry.setContext(new ContextImpl());
+        CoreRegistry.setContext(new ContextImplementation());
     }
 
     @Test
     public void testSharePopulatesCoreRegistry() {
-        assertNull(CoreRegistry.get(ServiceA.class));
+        Assertions.assertNull(CoreRegistry.get(ServiceA.class));
 
         InjectionHelper.share(serviceA);
 
-        assertEquals(CoreRegistry.get(ServiceA.class), serviceA);
+        Assertions.assertEquals(CoreRegistry.get(ServiceA.class), serviceA);
     }
 
     @Test
     public void testShareRequiresShareAnnotation() {
         InjectionHelper.share(new ServiceAImplNoAnnotation());
 
-        assertNull(CoreRegistry.get(ServiceA.class));
+        Assertions.assertNull(CoreRegistry.get(ServiceA.class));
     }
 
     @Test
@@ -52,8 +48,8 @@ public void testDefaultFieldInjection() {
         FieldInjectionAB fieldInjectionAB = new FieldInjectionAB();
         InjectionHelper.inject(fieldInjectionAB);
 
-        assertEquals(fieldInjectionAB.getServiceA(), serviceA);
-        assertEquals(fieldInjectionAB.getServiceB(), serviceB);
+        Assertions.assertEquals(fieldInjectionAB.getServiceA(), serviceA);
+        Assertions.assertEquals(fieldInjectionAB.getServiceB(), serviceB);
     }
 
     @Test
@@ -64,54 +60,54 @@ public void testInjectUnavailableObject() {
         FieldInjectionAB fieldInjectionAB = new FieldInjectionAB();
         InjectionHelper.inject(fieldInjectionAB);
 
-        assertEquals(fieldInjectionAB.getServiceA(), serviceA);
-        assertNull(fieldInjectionAB.getServiceB());
+        Assertions.assertEquals(fieldInjectionAB.getServiceA(), serviceA);
+        Assertions.assertNull(fieldInjectionAB.getServiceB());
     }
 
     @Test
     public void testDefaultConstructorInjection() {
-        Context context = new ContextImpl();
+        Context context = new ContextImplementation();
         context.put(ServiceA.class, serviceA);
         context.put(ServiceB.class, serviceB);
 
         ConstructorAB constructorAB = InjectionHelper.createWithConstructorInjection(ConstructorAB.class, context);
 
         //the two-arg constructor should be used as it has the most parameters and all can be populated
-        assertEquals(constructorAB.getServiceA(), serviceA);
-        assertEquals(constructorAB.getServiceB(), serviceB);
+        Assertions.assertEquals(constructorAB.getServiceA(), serviceA);
+        Assertions.assertEquals(constructorAB.getServiceB(), serviceB);
     }
 
     @Test
     public void testConstructorInjectionNotAllParametersPopulated() {
-        Context context = new ContextImpl();
+        Context context = new ContextImplementation();
         context.put(ServiceA.class, serviceA);
         //context.put(ServiceB.class, serviceB);
 
         ConstructorAB constructorAB = InjectionHelper.createWithConstructorInjection(ConstructorAB.class, context);
 
         //the two-arg constructor can't be populated because serviceB is not available
         //there is no fallback for a constructor with only serviceA, so the default constructor is called
-        assertNull(constructorAB.getServiceA());
-        assertNull(constructorAB.getServiceB());
+        Assertions.assertNull(constructorAB.getServiceA());
+        Assertions.assertNull(constructorAB.getServiceB());
     }
 
     @SuppressWarnings("checkstyle:LocalVariableName")
     @Test
     public void testConstructorInjectionNotAllParametersPopulatedFallback() {
-        Context context = new ContextImpl();
+        Context context = new ContextImplementation();
         context.put(ServiceA.class, serviceA);
         //context.put(ServiceB.class, serviceB);
 
         ConstructorA_AB constructorA_AB = InjectionHelper.createWithConstructorInjection(ConstructorA_AB.class, context);
 
         //the one-arg constructor is used as it can be populated  with serviceA which is available
-        assertEquals(constructorA_AB.getServiceA(), serviceA);
-        assertNull(constructorA_AB.getServiceB());
+        Assertions.assertEquals(constructorA_AB.getServiceA(), serviceA);
+        Assertions.assertNull(constructorA_AB.getServiceB());
     }
 
     @Test
     public void testConstructorInjectionNoDefaultConstructorForFallback() {
-        Context context = new ContextImpl();
+        Context context = new ContextImplementation();
         context.put(ServiceA.class, serviceA);
         //context.put(ServiceB.class, serviceB);