Support object declarations in DI generator

injector-generator/src/org/jetbrains/jet/di/Dependencies.java

@@ -123,25 +123,31 @@ public class Dependencies {
     }
 
     private void initializeByConstructorCall(Field field, ImmutableStack<Field> neededFor) {
-        Expression initialization = field.getInitialization();
-        DiType type = ((InstantiateType) initialization).getType();
+        //noinspection RedundantCast
+        DiType type = ((InstantiateType) field.getInitialization()).getType();
 
-        if (type.getClazz().isInterface()) {
-            throw new IllegalArgumentException("cannot instantiate interface: " + type.getClazz().getName() + " needed for " + neededFor);
+        Class<?> clazz = type.getClazz();
+        if (clazz.isInterface()) {
+            throw new IllegalArgumentException("cannot instantiate interface: " + clazz.getName() + " needed for " + neededFor);
         }
-        if (Modifier.isAbstract(type.getClazz().getModifiers())) {
-            throw new IllegalArgumentException("cannot instantiate abstract class: " + type.getClazz().getName() + " needed for " + neededFor);
+        if (Modifier.isAbstract(clazz.getModifiers())) {
+            throw new IllegalArgumentException("cannot instantiate abstract class: " + clazz.getName() + " needed for " + neededFor);
         }
 
         // Note: projections are not computed here
 
+        if (isKotlinSingletonObject(clazz)) {
+            field.setInitialization(new ObjectInstanceFieldAccess(clazz));
+            return;
+        }
+
         // Look for constructor
-        Constructor<?>[] constructors = type.getClazz().getConstructors();
+        Constructor<?>[] constructors = clazz.getConstructors();
         if (constructors.length == 0 || !Modifier.isPublic(constructors[0].getModifiers())) {
-            throw new IllegalArgumentException("No constructor: " + type.getClazz().getName() + " needed for " + neededFor);
+            throw new IllegalArgumentException("No constructor: " + clazz.getName() + " needed for " + neededFor);
         }
         if (constructors.length > 1) {
-            throw new IllegalArgumentException("Too many constructors in " + type.getClazz().getName() + " needed for " + neededFor);
+            throw new IllegalArgumentException("Too many constructors in " + clazz.getName() + " needed for " + neededFor);
         }
         Constructor<?> constructor = constructors[0];
 
@@ -161,6 +167,16 @@ public class Dependencies {
         field.setInitialization(dependency);
     }
 
+    private static boolean isKotlinSingletonObject(Class<?> clazz) {
+        try {
+            clazz.getDeclaredField("INSTANCE$");
+            return true;
+        }
+        catch (NoSuchFieldException e) {
+            return false;
+        }
+    }
+
     public Collection<Field> satisfyDependencies() {
         for (Field field : Lists.newArrayList(allFields)) {
             satisfyDependenciesFor(field, LinkedImmutableStack.<Field>empty());

injector-generator/src/org/jetbrains/jet/di/ObjectInstanceFieldAccess.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.di;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Collection;
+import java.util.Collections;
+
+public class ObjectInstanceFieldAccess implements Expression {
+    private final Class<?> clazz;
+
+    public ObjectInstanceFieldAccess(@NotNull Class<?> clazz) {
+        this.clazz = clazz;
+    }
+
+    @NotNull
+    @Override
+    public String renderAsCode() {
+        return clazz.getSimpleName() + ".INSTANCE$";
+    }
+
+    @NotNull
+    @Override
+    public Collection<DiType> getTypesToImport() {
+        return Collections.singleton(new DiType(clazz));
+    }
+
+    @Nullable
+    @Override
+    public DiType getType() {
+        return new DiType(clazz);
+    }
+
+    @Override
+    public String toString() {
+        return clazz.toString();
+    }
+}