StorageComponentContainer: allow to specify parent container which can be reused to provide components to several child containers

compiler/container/src/org/jetbrains/kotlin/container/Container.kt

@@ -38,9 +38,12 @@ object DynamicComponentDescriptor : ValueDescriptor {
     override fun toString(): String = "Dynamic"
 }
 
-class StorageComponentContainer(id: String) : ComponentContainer, ComponentProvider, Closeable {
-    val unknownContext: ComponentResolveContext by lazy { ComponentResolveContext(this, DynamicComponentDescriptor) }
-    val componentStorage = ComponentStorage(id)
+class StorageComponentContainer(id: String, parent: StorageComponentContainer? = null) : ComponentContainer, ComponentProvider, Closeable {
+    val unknownContext: ComponentResolveContext by lazy {
+        val parentContext = parent?.let { ComponentResolveContext(it, DynamicComponentDescriptor) }
+        ComponentResolveContext(this, DynamicComponentDescriptor, parentContext)
+    }
+    val componentStorage: ComponentStorage = ComponentStorage(id, parent?.componentStorage)
 
     override fun createResolveContext(requestingDescriptor: ValueDescriptor): ValueResolveContext {
         if (requestingDescriptor == DynamicComponentDescriptor) // cache unknown component descriptor

compiler/container/src/org/jetbrains/kotlin/container/Dsl.kt

@@ -18,8 +18,8 @@ package org.jetbrains.kotlin.container
 
 import kotlin.reflect.KProperty
 
-fun createContainer(id: String, init: StorageComponentContainer.() -> Unit): StorageComponentContainer {
-    val c = StorageComponentContainer(id)
+fun createContainer(id: String, parent: StorageComponentContainer? = null, init: StorageComponentContainer.() -> Unit): StorageComponentContainer {
+    val c = StorageComponentContainer(id, parent)
     c.init()
     c.compose()
     return c

compiler/container/src/org/jetbrains/kotlin/container/Registry.kt

@@ -17,8 +17,7 @@
 package org.jetbrains.kotlin.container
 
 import com.intellij.util.containers.MultiMap
-import java.util.ArrayList
-import java.lang.reflect.*
+import java.lang.reflect.Type
 
 internal class ComponentRegistry {
     fun buildRegistrationMap(descriptors: Collection<ComponentDescriptor>): MultiMap<Type, ComponentDescriptor> {
@@ -40,4 +39,8 @@ internal class ComponentRegistry {
     fun tryGetEntry(request: Type): Collection<ComponentDescriptor> {
         return registrationMap.get(request)
     }
+
+    fun addAll(other: ComponentRegistry) {
+        registrationMap.putAllValues(other.registrationMap)
+    }
 }

compiler/container/src/org/jetbrains/kotlin/container/Resolve.kt

@@ -30,8 +30,12 @@ interface ValueResolveContext {
     fun resolve(registration: Type): ValueDescriptor?
 }
 
-class ComponentResolveContext(val container: StorageComponentContainer, val requestingDescriptor: ValueDescriptor) : ValueResolveContext {
-    override fun resolve(registration: Type): ValueDescriptor? = container.resolve(registration, this)
+class ComponentResolveContext(
+        val container: StorageComponentContainer,
+        val requestingDescriptor: ValueDescriptor,
+        val parentContext: ValueResolveContext? = null
+) : ValueResolveContext {
+    override fun resolve(registration: Type): ValueDescriptor? = container.resolve(registration, this) ?: parentContext?.resolve(registration)
 
     override fun toString(): String = "for $requestingDescriptor in $container"
 }

compiler/container/src/org/jetbrains/kotlin/container/Storage.kt

@@ -35,9 +35,13 @@ enum class ComponentStorageState {
 
 internal class InvalidCardinalityException(message: String, val descriptors: Collection<ComponentDescriptor>) : Exception(message)
 
-class ComponentStorage(val myId: String) : ValueResolver {
+class ComponentStorage(val myId: String, parent: ComponentStorage?) : ValueResolver {
     var state = ComponentStorageState.Initial
     private val registry = ComponentRegistry()
+    init {
+        parent?.let { registry.addAll(it.registry) }
+    }
+
     private val descriptors = LinkedHashSet<ComponentDescriptor>()
     private val dependencies = MultiMap.createLinkedSet<ComponentDescriptor, Type>()
 

compiler/container/tests/org/jetbrains/kotlin/container/tests/ComponentContainerTest.kt

@@ -270,4 +270,46 @@ class ComponentContainerTest {
         assertTrue(c is C)
     }
 
+    @Test
+    fun use_parent_context_to_discover_dependencies() {
+        class A
+        class B(val a: A)
+
+        val ac = createContainer("a") {
+            useImpl<A>()
+        }
+
+        val bc = createContainer("b", ac) {
+            useImpl<B>()
+        }
+        val b = bc.get<B>()
+
+        val a = ac.get<A>()
+        assertTrue(b is B)
+        assertTrue(b.a is A)
+        assertTrue(a is A)
+        assertTrue(b.a === a)
+    }
+
+    @Test
+    fun several_child_dependencies() {
+        class A
+        class B(val a: A)
+
+        val ac = createContainer("a") {
+            useImpl<A>()
+        }
+
+        val bc1 = createContainer("b1", ac) {
+            useImpl<B>()
+        }
+        val bc2 = createContainer("b2", ac) {
+            useImpl<B>()
+        }
+        val a = ac.get<A>()
+        assertTrue(a is A)
+        assertTrue(a === bc2.get<B>().a)
+        assertTrue(a === bc1.get<B>().a)
+        assertTrue(a === bc1.get<A>())
+    }
 }