diff --git a/js/js.inliner/src/org/jetbrains/k2js/inline/util/collectionUtils.kt b/js/js.inliner/src/org/jetbrains/k2js/inline/util/collectionUtils.kt
new file mode 100644
index 00000000000..5a7751174c8
--- /dev/null
+++ b/js/js.inliner/src/org/jetbrains/k2js/inline/util/collectionUtils.kt
@@ -0,0 +1,65 @@
+/*
+ * 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.k2js.inline.util
+
+import java.util.Collections
+import java.util.IdentityHashMap
+
+public fun IdentitySet<T>(): MutableSet<T> {
+    return Collections.newSetFromMap(IdentityHashMap<T, Boolean>())
+}
+
+public fun <T> Collection<T>.toIdentitySet(): MutableSet<T> {
+    val result = IdentitySet<T>()
+    for (element in this) {
+        result.add(element)
+    }
+
+    return result
+}
+
+public fun <T> Stream<T>.toIdentitySet(): MutableSet<T> {
+    val result = IdentitySet<T>()
+    for (element in this) {
+        result.add(element)
+    }
+
+    return result
+}
+
+public fun <T, R> Iterable<T>.zipWithDefault(
+        other: Iterable<R>,
+        defaultT: T
+): List<Pair<T, R>> {
+
+    val itT = iterator()
+    val itR = other.iterator()
+
+    val result = arrayListOf<Pair<T, R>>()
+
+    while (itT.hasNext() && itR.hasNext()) {
+        result.add(itT.next() to itR.next())
+    }
+
+    assert(!itT.hasNext()) { "First collection is bigger than second" }
+
+    while (itR.hasNext()) {
+        result.add(defaultT to itR.next())
+    }
+
+    return result
+}
\ No newline at end of file