From 132f2a5fa8ba58a32b0c58ef2dd5e747d65e0d88 Mon Sep 17 00:00:00 2001
From: Ilya Ryzhenkov <orangy@jetbrains.com>
Date: Mon, 9 Jun 2014 14:51:05 +0400
Subject: [PATCH] Improve performance for addAll with type check for Collection

---
 .../stdlib/src/kotlin/collections/MutableCollections.kt      | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libraries/stdlib/src/kotlin/collections/MutableCollections.kt b/libraries/stdlib/src/kotlin/collections/MutableCollections.kt
index 1a99bebe612..ba221cfd04c 100644
--- a/libraries/stdlib/src/kotlin/collections/MutableCollections.kt
+++ b/libraries/stdlib/src/kotlin/collections/MutableCollections.kt
@@ -4,7 +4,10 @@ package kotlin
  * Adds all elements of the given *iterable* to this [[MutableCollection]]
  */
 public fun <T> MutableCollection<in T>.addAll(iterable: Iterable<T>): Unit {
-    for (e in iterable) add(e)
+    when (iterable) {
+        is Collection -> addAll(iterable)
+        else -> for (e in iterable) add(e)
+    }
 }
 
 public fun <T> MutableCollection<in T>.addAll(stream: Stream<T>): Unit {