Lazy made serializable.

libraries/stdlib/src/kotlin/util/Lazy.kt

@@ -1,5 +1,7 @@
 package kotlin
 
+import java.io.Serializable
+
 
 /**
  * Represents a value with lazy initialization.
@@ -40,11 +42,11 @@ public enum class LazyThreadSafetyMode {
 
 private object UNINITIALIZED_VALUE
 
-private class LazyImpl<out T>(initializer: () -> T) : Lazy<T> {
+private class LazyImpl<out T>(initializer: () -> T) : Lazy<T>, Serializable {
     private var initializer: (() -> T)? = initializer
     private volatile var _value: Any? = UNINITIALIZED_VALUE
 
-    public override val value: T
+    override val value: T
         get() {
             val _v1 = _value
             if (_v1 !== UNINITIALIZED_VALUE) {
@@ -65,16 +67,16 @@ private class LazyImpl<out T>(initializer: () -> T) : Lazy<T> {
             }
         }
 
-    override val valueCreated: Boolean = _value !== UNINITIALIZED_VALUE
+    override val valueCreated: Boolean get() = _value !== UNINITIALIZED_VALUE
 
     override fun toString(): String = if (valueCreated) value.toString() else "Lazy value not initialized yet."
+
+    private fun writeReplace(): Any = InitializedLazyImpl(value)
 }
 
 
-private class UnsafeLazyImpl<out T>(initializer: () -> T) : Lazy<T> {
+private class UnsafeLazyImpl<out T>(initializer: () -> T) : Lazy<T>, Serializable {
     private var initializer: (() -> T)? = initializer
-
-
     private var _value: Any? = UNINITIALIZED_VALUE
 
     override val value: T
@@ -86,7 +88,17 @@ private class UnsafeLazyImpl<out T>(initializer: () -> T) : Lazy<T> {
             return _value as T
         }
 
-    override val valueCreated: Boolean = _value !== UNINITIALIZED_VALUE
+    override val valueCreated: Boolean get() = _value !== UNINITIALIZED_VALUE
 
     override fun toString(): String = if (valueCreated) value.toString() else "Lazy value not initialized yet."
+
+    private fun writeReplace(): Any = InitializedLazyImpl(value)
+}
+
+private class InitializedLazyImpl<out T>(override val value: T) : Lazy<T>, Serializable {
+
+    override val valueCreated: Boolean get() = true
+
+    override fun toString(): String = value.toString()
+
 }

libraries/stdlib/test/collections/CollectionJVMTest.kt

@@ -154,19 +154,23 @@ class CollectionJVMTest {
     test fun emptyMapIsSerializable() = testSingletonSerialization(emptyMap<Any, Any>())
 
     private fun testSingletonSerialization(value: Any) {
-        val outputStream = ByteArrayOutputStream()
-        val objectOuputStream = ObjectOutputStream(outputStream)
+        val result = serializeAndDeserialize(value)
 
-        objectOuputStream.writeObject(value)
-        objectOuputStream.close()
+        assertEquals(value, result)
+        assertTrue(value === result)
+    }
+
+    private fun serializeAndDeserialize<T>(value: T): T {
+        val outputStream = ByteArrayOutputStream()
+        val objectOutputStream = ObjectOutputStream(outputStream)
+
+        objectOutputStream.writeObject(value)
+        objectOutputStream.close()
         outputStream.close()
 
         val inputStream = ByteArrayInputStream(outputStream.toByteArray())
         val inputObjectStream = ObjectInputStream(inputStream)
-        val result = inputObjectStream.readObject()
-
-        assertEquals(value, result)
-        assertTrue(value === result)
+        return inputObjectStream.readObject() as T
     }
 }
 

libraries/stdlib/test/utils/LazyJVMTest.kt

@@ -0,0 +1,36 @@
+package test.utils
+
+
+import kotlin.*
+import kotlin.test.*
+import java.io.*
+import org.junit.Test as test
+
+class LazyJVMTest {
+
+    test fun lazyInitializationForcedOnSerialization() {
+        for(mode in listOf(LazyThreadSafetyMode.SYNCHRONIZED, LazyThreadSafetyMode.NONE)) {
+            val lazy = lazy(mode) { "initialized" }
+            assertFalse(lazy.valueCreated)
+            val lazy2 = serializeAndDeserialize(lazy)
+            assertTrue(lazy.valueCreated)
+            assertTrue(lazy2.valueCreated)
+            assertEquals(lazy.value, lazy2.value)
+        }
+    }
+
+
+    private fun serializeAndDeserialize<T>(value: T): T {
+        val outputStream = ByteArrayOutputStream()
+        val objectOutputStream = ObjectOutputStream(outputStream)
+
+        objectOutputStream.writeObject(value)
+        objectOutputStream.close()
+        outputStream.close()
+
+        val inputStream = ByteArrayInputStream(outputStream.toByteArray())
+        val inputObjectStream = ObjectInputStream(inputStream)
+        return inputObjectStream.readObject() as T
+    }
+
+}

libraries/stdlib/test/utils/LazyTest.kt

@@ -0,0 +1,45 @@
+package test.utils
+
+import kotlin.*
+import kotlin.test.*
+import org.junit.Test as test
+
+class LazyTest {
+
+    test fun initializationCalledOnce() {
+        var callCount = 0
+        val lazyInt = lazy { ++callCount }
+
+        assertEquals(0, callCount)
+        assertEquals(1, lazyInt.value)
+        assertEquals(1, callCount)
+
+        lazyInt.value
+        assertEquals(1, callCount)
+    }
+
+    test fun valueCreated() {
+        var callCount = 0
+        val lazyInt = lazy { ++callCount }
+
+        assertFalse(lazyInt.valueCreated)
+        assertEquals(0, callCount)
+
+        lazyInt.value
+
+        assertTrue(lazyInt.valueCreated)
+    }
+
+
+    test fun lazyToString() {
+        var callCount = 0
+        val lazyInt = lazy { ++callCount }
+
+        assertNotEquals("1", lazyInt.toString())
+        assertEquals(0, callCount)
+
+        assertEquals(1, lazyInt.value)
+        assertEquals("1", lazyInt.toString())
+        assertEquals(1, callCount)
+    }
+}