From d831509ceef9c330fe3b60cf501e64445241f581 Mon Sep 17 00:00:00 2001
From: Ilya Gorbunov <ilya.gorbunov@jetbrains.com>
Date: Mon, 20 Jul 2015 18:27:58 +0300
Subject: [PATCH] Provide listOfNotNull method.

---
 libraries/stdlib/src/kotlin/collections/JUtil.kt    |  6 ++++++
 libraries/stdlib/test/collections/CollectionTest.kt | 12 ++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/libraries/stdlib/src/kotlin/collections/JUtil.kt b/libraries/stdlib/src/kotlin/collections/JUtil.kt
index 44c1aa0cd84..572ac9ee6f8 100644
--- a/libraries/stdlib/src/kotlin/collections/JUtil.kt
+++ b/libraries/stdlib/src/kotlin/collections/JUtil.kt
@@ -85,6 +85,12 @@ public fun hashSetOf<T>(vararg values: T): HashSet<T> = values.toCollection(Hash
 /** Returns a new [LinkedHashSet] with the given elements. */
 public fun linkedSetOf<T>(vararg values: T): LinkedHashSet<T> = values.toCollection(LinkedHashSet(mapCapacity(values.size())))
 
+/** Returns a new read-only list either of single given element, if it is not null, or empty list it the element is null. The returned list is serializable (JVM). */
+public fun <T : Any> listOfNotNull(value: T?): List<T> = if (value != null) listOf(value) else emptyList()
+
+/** Returns a new read-only list only of those given elements, that are not null.  The returned list is serializable (JVM). */
+public fun <T : Any> listOfNotNull(vararg values: T?): List<T> = values.filterNotNull()
+
 /**
  * Returns an [IntRange] of the valid indices for this collection.
  */
diff --git a/libraries/stdlib/test/collections/CollectionTest.kt b/libraries/stdlib/test/collections/CollectionTest.kt
index a213fd01634..ad60d7dd3c2 100644
--- a/libraries/stdlib/test/collections/CollectionTest.kt
+++ b/libraries/stdlib/test/collections/CollectionTest.kt
@@ -47,6 +47,18 @@ class CollectionTest {
         }
     }
 
+    test fun listOfNotNull() {
+        val l1: List<Int> = listOfNotNull(null)
+        assertTrue(l1.isEmpty())
+
+        val s: String? = "value"
+        val l2: List<String> = listOfNotNull(s)
+        assertEquals(s, l2.single())
+
+        val l3: List<String> = listOfNotNull("value1", null, "value2")
+        assertEquals(listOf("value1", "value2"), l3)
+    }
+
     test fun filterIntoSet() {
         val data = listOf("foo", "bar")
         val foo = data.filterTo(hashSetOf<String>()) { it.startsWith("f") }