From d908678dcfd493c24df51b6696945c86dd3a876e Mon Sep 17 00:00:00 2001
From: Ilya Ryzhenkov <orangy@jetbrains.com>
Date: Mon, 22 Dec 2014 23:34:46 +0300
Subject: [PATCH] Take into account collection sizes when possible #KT-6180

---
 libraries/stdlib/src/generated/_Filtering.kt  | 20 ++---
 libraries/stdlib/src/generated/_Generators.kt | 82 +++++--------------
 libraries/stdlib/src/generated/_Mapping.kt    | 22 ++---
 libraries/stdlib/src/generated/_Snapshots.kt  | 12 +--
 .../stdlib/src/kotlin/collections/JUtil.kt    |  3 +
 .../src/templates/Filtering.kt                |  2 +-
 .../src/templates/Generators.kt               | 37 +++++++--
 .../src/templates/Mapping.kt                  |  9 +-
 .../src/templates/Snapshots.kt                | 33 ++------
 9 files changed, 97 insertions(+), 123 deletions(-)

diff --git a/libraries/stdlib/src/generated/_Filtering.kt b/libraries/stdlib/src/generated/_Filtering.kt
index 9674752548c..9deca84e2ed 100644
--- a/libraries/stdlib/src/generated/_Filtering.kt
+++ b/libraries/stdlib/src/generated/_Filtering.kt
@@ -12,7 +12,7 @@ import java.util.*
  */
 public fun <T> Array<out T>.drop(n: Int): List<T> {
     if (n >= size())
-        return ArrayList<T>()
+        return emptyList()
     var count = 0
     val list = ArrayList<T>(size() - n)
     for (item in this) {
@@ -26,7 +26,7 @@ public fun <T> Array<out T>.drop(n: Int): List<T> {
  */
 public fun BooleanArray.drop(n: Int): List<Boolean> {
     if (n >= size())
-        return ArrayList<Boolean>()
+        return emptyList()
     var count = 0
     val list = ArrayList<Boolean>(size() - n)
     for (item in this) {
@@ -40,7 +40,7 @@ public fun BooleanArray.drop(n: Int): List<Boolean> {
  */
 public fun ByteArray.drop(n: Int): List<Byte> {
     if (n >= size())
-        return ArrayList<Byte>()
+        return emptyList()
     var count = 0
     val list = ArrayList<Byte>(size() - n)
     for (item in this) {
@@ -54,7 +54,7 @@ public fun ByteArray.drop(n: Int): List<Byte> {
  */
 public fun CharArray.drop(n: Int): List<Char> {
     if (n >= size())
-        return ArrayList<Char>()
+        return emptyList()
     var count = 0
     val list = ArrayList<Char>(size() - n)
     for (item in this) {
@@ -68,7 +68,7 @@ public fun CharArray.drop(n: Int): List<Char> {
  */
 public fun DoubleArray.drop(n: Int): List<Double> {
     if (n >= size())
-        return ArrayList<Double>()
+        return emptyList()
     var count = 0
     val list = ArrayList<Double>(size() - n)
     for (item in this) {
@@ -82,7 +82,7 @@ public fun DoubleArray.drop(n: Int): List<Double> {
  */
 public fun FloatArray.drop(n: Int): List<Float> {
     if (n >= size())
-        return ArrayList<Float>()
+        return emptyList()
     var count = 0
     val list = ArrayList<Float>(size() - n)
     for (item in this) {
@@ -96,7 +96,7 @@ public fun FloatArray.drop(n: Int): List<Float> {
  */
 public fun IntArray.drop(n: Int): List<Int> {
     if (n >= size())
-        return ArrayList<Int>()
+        return emptyList()
     var count = 0
     val list = ArrayList<Int>(size() - n)
     for (item in this) {
@@ -110,7 +110,7 @@ public fun IntArray.drop(n: Int): List<Int> {
  */
 public fun LongArray.drop(n: Int): List<Long> {
     if (n >= size())
-        return ArrayList<Long>()
+        return emptyList()
     var count = 0
     val list = ArrayList<Long>(size() - n)
     for (item in this) {
@@ -124,7 +124,7 @@ public fun LongArray.drop(n: Int): List<Long> {
  */
 public fun ShortArray.drop(n: Int): List<Short> {
     if (n >= size())
-        return ArrayList<Short>()
+        return emptyList()
     var count = 0
     val list = ArrayList<Short>(size() - n)
     for (item in this) {
@@ -138,7 +138,7 @@ public fun ShortArray.drop(n: Int): List<Short> {
  */
 public fun <T> Collection<T>.drop(n: Int): List<T> {
     if (n >= size())
-        return ArrayList<T>()
+        return emptyList()
     var count = 0
     val list = ArrayList<T>(size() - n)
     for (item in this) {
diff --git a/libraries/stdlib/src/generated/_Generators.kt b/libraries/stdlib/src/generated/_Generators.kt
index 21b8cc77c28..2cc7d676928 100644
--- a/libraries/stdlib/src/generated/_Generators.kt
+++ b/libraries/stdlib/src/generated/_Generators.kt
@@ -13,7 +13,7 @@ import java.util.*
 public inline fun <T, R, V> Array<out T>.merge(array: Array<out R>, transform: (T, R) -> V): List<V> {
     val first = iterator()
     val second = array.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -26,7 +26,7 @@ public inline fun <T, R, V> Array<out T>.merge(array: Array<out R>, transform: (
 public inline fun <R, V> BooleanArray.merge(array: Array<out R>, transform: (Boolean, R) -> V): List<V> {
     val first = iterator()
     val second = array.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -39,7 +39,7 @@ public inline fun <R, V> BooleanArray.merge(array: Array<out R>, transform: (Boo
 public inline fun <R, V> ByteArray.merge(array: Array<out R>, transform: (Byte, R) -> V): List<V> {
     val first = iterator()
     val second = array.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -52,7 +52,7 @@ public inline fun <R, V> ByteArray.merge(array: Array<out R>, transform: (Byte,
 public inline fun <R, V> CharArray.merge(array: Array<out R>, transform: (Char, R) -> V): List<V> {
     val first = iterator()
     val second = array.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -65,7 +65,7 @@ public inline fun <R, V> CharArray.merge(array: Array<out R>, transform: (Char,
 public inline fun <R, V> DoubleArray.merge(array: Array<out R>, transform: (Double, R) -> V): List<V> {
     val first = iterator()
     val second = array.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -78,7 +78,7 @@ public inline fun <R, V> DoubleArray.merge(array: Array<out R>, transform: (Doub
 public inline fun <R, V> FloatArray.merge(array: Array<out R>, transform: (Float, R) -> V): List<V> {
     val first = iterator()
     val second = array.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -91,7 +91,7 @@ public inline fun <R, V> FloatArray.merge(array: Array<out R>, transform: (Float
 public inline fun <R, V> IntArray.merge(array: Array<out R>, transform: (Int, R) -> V): List<V> {
     val first = iterator()
     val second = array.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -104,7 +104,7 @@ public inline fun <R, V> IntArray.merge(array: Array<out R>, transform: (Int, R)
 public inline fun <R, V> LongArray.merge(array: Array<out R>, transform: (Long, R) -> V): List<V> {
     val first = iterator()
     val second = array.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -117,7 +117,7 @@ public inline fun <R, V> LongArray.merge(array: Array<out R>, transform: (Long,
 public inline fun <R, V> ShortArray.merge(array: Array<out R>, transform: (Short, R) -> V): List<V> {
     val first = iterator()
     val second = array.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -130,20 +130,7 @@ public inline fun <R, V> ShortArray.merge(array: Array<out R>, transform: (Short
 public inline fun <T, R, V> Iterable<T>.merge(array: Array<out R>, transform: (T, R) -> V): List<V> {
     val first = iterator()
     val second = array.iterator()
-    val list = arrayListOf<V>()
-    while (first.hasNext() && second.hasNext()) {
-        list.add(transform(first.next(), second.next()))
-    }
-    return list
-}
-
-/**
- * Returns a list of values built from elements of both collections with same indexes using provided *transform*. List has length of shortest collection.
- */
-public inline fun <R, V> String.merge(array: Array<out R>, transform: (Char, R) -> V): List<V> {
-    val first = iterator()
-    val second = array.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(collectionSizeOrDefault(10))
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -156,7 +143,7 @@ public inline fun <R, V> String.merge(array: Array<out R>, transform: (Char, R)
 public inline fun <T, R, V> Array<out T>.merge(other: Iterable<R>, transform: (T, R) -> V): List<V> {
     val first = iterator()
     val second = other.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -169,7 +156,7 @@ public inline fun <T, R, V> Array<out T>.merge(other: Iterable<R>, transform: (T
 public inline fun <R, V> BooleanArray.merge(other: Iterable<R>, transform: (Boolean, R) -> V): List<V> {
     val first = iterator()
     val second = other.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -182,7 +169,7 @@ public inline fun <R, V> BooleanArray.merge(other: Iterable<R>, transform: (Bool
 public inline fun <R, V> ByteArray.merge(other: Iterable<R>, transform: (Byte, R) -> V): List<V> {
     val first = iterator()
     val second = other.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -195,7 +182,7 @@ public inline fun <R, V> ByteArray.merge(other: Iterable<R>, transform: (Byte, R
 public inline fun <R, V> CharArray.merge(other: Iterable<R>, transform: (Char, R) -> V): List<V> {
     val first = iterator()
     val second = other.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -208,7 +195,7 @@ public inline fun <R, V> CharArray.merge(other: Iterable<R>, transform: (Char, R
 public inline fun <R, V> DoubleArray.merge(other: Iterable<R>, transform: (Double, R) -> V): List<V> {
     val first = iterator()
     val second = other.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -221,7 +208,7 @@ public inline fun <R, V> DoubleArray.merge(other: Iterable<R>, transform: (Doubl
 public inline fun <R, V> FloatArray.merge(other: Iterable<R>, transform: (Float, R) -> V): List<V> {
     val first = iterator()
     val second = other.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -234,7 +221,7 @@ public inline fun <R, V> FloatArray.merge(other: Iterable<R>, transform: (Float,
 public inline fun <R, V> IntArray.merge(other: Iterable<R>, transform: (Int, R) -> V): List<V> {
     val first = iterator()
     val second = other.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -247,7 +234,7 @@ public inline fun <R, V> IntArray.merge(other: Iterable<R>, transform: (Int, R)
 public inline fun <R, V> LongArray.merge(other: Iterable<R>, transform: (Long, R) -> V): List<V> {
     val first = iterator()
     val second = other.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -260,7 +247,7 @@ public inline fun <R, V> LongArray.merge(other: Iterable<R>, transform: (Long, R
 public inline fun <R, V> ShortArray.merge(other: Iterable<R>, transform: (Short, R) -> V): List<V> {
     val first = iterator()
     val second = other.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(size())
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -273,20 +260,7 @@ public inline fun <R, V> ShortArray.merge(other: Iterable<R>, transform: (Short,
 public inline fun <T, R, V> Iterable<T>.merge(other: Iterable<R>, transform: (T, R) -> V): List<V> {
     val first = iterator()
     val second = other.iterator()
-    val list = arrayListOf<V>()
-    while (first.hasNext() && second.hasNext()) {
-        list.add(transform(first.next(), second.next()))
-    }
-    return list
-}
-
-/**
- * Returns a list of values built from elements of both collections with same indexes using provided *transform*. List has length of shortest collection.
- */
-public inline fun <R, V> String.merge(other: Iterable<R>, transform: (Char, R) -> V): List<V> {
-    val first = iterator()
-    val second = other.iterator()
-    val list = arrayListOf<V>()
+    val list = ArrayList<V>(collectionSizeOrDefault(10))
     while (first.hasNext() && second.hasNext()) {
         list.add(transform(first.next(), second.next()))
     }
@@ -877,13 +851,6 @@ public fun <T, R> Iterable<T>.zip(array: Array<out R>): List<Pair<T, R>> {
     return merge(array) { (t1, t2) -> t1 to t2 }
 }
 
-/**
- * Returns a list of pairs built from elements of both collections with same indexes. List has length of shortest collection.
- */
-public fun <R> String.zip(array: Array<out R>): List<Pair<Char, R>> {
-    return merge(array) { (t1, t2) -> t1 to t2 }
-}
-
 /**
  * Returns a list of pairs built from elements of both collections with same indexes. List has length of shortest collection.
  */
@@ -954,20 +921,13 @@ public fun <T, R> Iterable<T>.zip(other: Iterable<R>): List<Pair<T, R>> {
     return merge(other) { (t1, t2) -> t1 to t2 }
 }
 
-/**
- * Returns a list of pairs built from elements of both collections with same indexes. List has length of shortest collection.
- */
-public fun <R> String.zip(other: Iterable<R>): List<Pair<Char, R>> {
-    return merge(other) { (t1, t2) -> t1 to t2 }
-}
-
 /**
  * Returns a list of pairs built from characters of both strings with same indexes. List has length of shortest collection.
  */
 public fun String.zip(other: String): List<Pair<Char, Char>> {
     val first = iterator()
     val second = other.iterator()
-    val list = ArrayList<Pair<Char, Char>>()
+    val list = ArrayList<Pair<Char, Char>>(length())
     while (first.hasNext() && second.hasNext()) {
         list.add(first.next() to second.next())
     }
diff --git a/libraries/stdlib/src/generated/_Mapping.kt b/libraries/stdlib/src/generated/_Mapping.kt
index 894b7d7c0ef..776c4f457f5 100644
--- a/libraries/stdlib/src/generated/_Mapping.kt
+++ b/libraries/stdlib/src/generated/_Mapping.kt
@@ -564,70 +564,70 @@ public inline fun <R> String.map(transform: (Char) -> R): List<R> {
  * Returns a list containing the results of applying the given *transform* function to each element and its index of the original collection
  */
 public inline fun <T, R> Array<out T>.mapIndexed(transform: (Int, T) -> R): List<R> {
-    return mapIndexedTo(ArrayList<R>(), transform)
+    return mapIndexedTo(ArrayList<R>(size()), transform)
 }
 
 /**
  * Returns a list containing the results of applying the given *transform* function to each element and its index of the original collection
  */
 public inline fun <R> BooleanArray.mapIndexed(transform: (Int, Boolean) -> R): List<R> {
-    return mapIndexedTo(ArrayList<R>(), transform)
+    return mapIndexedTo(ArrayList<R>(size()), transform)
 }
 
 /**
  * Returns a list containing the results of applying the given *transform* function to each element and its index of the original collection
  */
 public inline fun <R> ByteArray.mapIndexed(transform: (Int, Byte) -> R): List<R> {
-    return mapIndexedTo(ArrayList<R>(), transform)
+    return mapIndexedTo(ArrayList<R>(size()), transform)
 }
 
 /**
  * Returns a list containing the results of applying the given *transform* function to each element and its index of the original collection
  */
 public inline fun <R> CharArray.mapIndexed(transform: (Int, Char) -> R): List<R> {
-    return mapIndexedTo(ArrayList<R>(), transform)
+    return mapIndexedTo(ArrayList<R>(size()), transform)
 }
 
 /**
  * Returns a list containing the results of applying the given *transform* function to each element and its index of the original collection
  */
 public inline fun <R> DoubleArray.mapIndexed(transform: (Int, Double) -> R): List<R> {
-    return mapIndexedTo(ArrayList<R>(), transform)
+    return mapIndexedTo(ArrayList<R>(size()), transform)
 }
 
 /**
  * Returns a list containing the results of applying the given *transform* function to each element and its index of the original collection
  */
 public inline fun <R> FloatArray.mapIndexed(transform: (Int, Float) -> R): List<R> {
-    return mapIndexedTo(ArrayList<R>(), transform)
+    return mapIndexedTo(ArrayList<R>(size()), transform)
 }
 
 /**
  * Returns a list containing the results of applying the given *transform* function to each element and its index of the original collection
  */
 public inline fun <R> IntArray.mapIndexed(transform: (Int, Int) -> R): List<R> {
-    return mapIndexedTo(ArrayList<R>(), transform)
+    return mapIndexedTo(ArrayList<R>(size()), transform)
 }
 
 /**
  * Returns a list containing the results of applying the given *transform* function to each element and its index of the original collection
  */
 public inline fun <R> LongArray.mapIndexed(transform: (Int, Long) -> R): List<R> {
-    return mapIndexedTo(ArrayList<R>(), transform)
+    return mapIndexedTo(ArrayList<R>(size()), transform)
 }
 
 /**
  * Returns a list containing the results of applying the given *transform* function to each element and its index of the original collection
  */
 public inline fun <R> ShortArray.mapIndexed(transform: (Int, Short) -> R): List<R> {
-    return mapIndexedTo(ArrayList<R>(), transform)
+    return mapIndexedTo(ArrayList<R>(size()), transform)
 }
 
 /**
  * Returns a list containing the results of applying the given *transform* function to each element and its index of the original collection
  */
 public inline fun <T, R> Iterable<T>.mapIndexed(transform: (Int, T) -> R): List<R> {
-    return mapIndexedTo(ArrayList<R>(), transform)
+    return mapIndexedTo(ArrayList<R>(collectionSizeOrDefault(10)), transform)
 }
 
 /**
@@ -641,7 +641,7 @@ public fun <T, R> Stream<T>.mapIndexed(transform: (Int, T) -> R): Stream<R> {
  * Returns a list containing the results of applying the given *transform* function to each element and its index of the original collection
  */
 public inline fun <R> String.mapIndexed(transform: (Int, Char) -> R): List<R> {
-    return mapIndexedTo(ArrayList<R>(), transform)
+    return mapIndexedTo(ArrayList<R>(length()), transform)
 }
 
 /**
diff --git a/libraries/stdlib/src/generated/_Snapshots.kt b/libraries/stdlib/src/generated/_Snapshots.kt
index 3f17c9fe558..1ffc5bba317 100644
--- a/libraries/stdlib/src/generated/_Snapshots.kt
+++ b/libraries/stdlib/src/generated/_Snapshots.kt
@@ -92,7 +92,7 @@ public fun ShortArray.toArrayList(): ArrayList<Short> {
  * Returns an ArrayList of all elements
  */
 public fun <T> Iterable<T>.toArrayList(): ArrayList<T> {
-    return toCollection(ArrayList<T>())
+    return toCollection(ArrayList<T>(collectionSizeOrDefault(10)))
 }
 
 /**
@@ -106,7 +106,7 @@ public fun <T> Stream<T>.toArrayList(): ArrayList<T> {
  * Returns an ArrayList of all elements
  */
 public fun String.toArrayList(): ArrayList<Char> {
-    return toCollection(ArrayList<Char>())
+    return toCollection(ArrayList<Char>(length()))
 }
 
 /**
@@ -411,7 +411,9 @@ public fun <K, V> Map<K, V>.toList(): List<Pair<K, V>> {
  * Returns a List containing all elements
  */
 public fun <T> Array<out T>.toList(): List<T> {
-    return toCollection(ArrayList<T>())
+    val list = ArrayList<T>(size())
+    for (item in this) list.add(item)
+    return list
 }
 
 /**
@@ -490,7 +492,7 @@ public fun ShortArray.toList(): List<Short> {
  * Returns a List containing all elements
  */
 public fun <T> Iterable<T>.toList(): List<T> {
-    return toCollection(ArrayList<T>())
+    return toCollection(ArrayList<T>(collectionSizeOrDefault(10)))
 }
 
 /**
@@ -504,7 +506,7 @@ public fun <T> Stream<T>.toList(): List<T> {
  * Returns a List containing all elements
  */
 public fun String.toList(): List<Char> {
-    return toCollection(ArrayList<Char>())
+    return toCollection(ArrayList<Char>(length()))
 }
 
 /**
diff --git a/libraries/stdlib/src/kotlin/collections/JUtil.kt b/libraries/stdlib/src/kotlin/collections/JUtil.kt
index b1b9a57a97f..d292f6cfa16 100644
--- a/libraries/stdlib/src/kotlin/collections/JUtil.kt
+++ b/libraries/stdlib/src/kotlin/collections/JUtil.kt
@@ -86,3 +86,6 @@ public fun <T> List<T>?.orEmpty(): List<T> = this ?: emptyList()
 
 /** Returns the List if its not null otherwise returns the empty list */
 public fun <T> Set<T>?.orEmpty(): Set<T> = this ?: emptySet()
+
+public fun <T> Iterable<T>.collectionSizeOrNull(): Int? = if (this is Collection<*>) size() else null
+public fun <T> Iterable<T>.collectionSizeOrDefault(default: Int): Int = if (this is Collection<*>) size() else default
\ No newline at end of file
diff --git a/libraries/tools/kotlin-stdlib-gen/src/templates/Filtering.kt b/libraries/tools/kotlin-stdlib-gen/src/templates/Filtering.kt
index 94be3ef24b3..b484c886bab 100644
--- a/libraries/tools/kotlin-stdlib-gen/src/templates/Filtering.kt
+++ b/libraries/tools/kotlin-stdlib-gen/src/templates/Filtering.kt
@@ -33,7 +33,7 @@ fun filtering(): List<GenericFunction> {
         body(Collections, ArraysOfObjects, ArraysOfPrimitives) {
             """
             if (n >= size())
-                return ArrayList<T>()
+                return emptyList()
 
             var count = 0
             val list = ArrayList<T>(size() - n)
diff --git a/libraries/tools/kotlin-stdlib-gen/src/templates/Generators.kt b/libraries/tools/kotlin-stdlib-gen/src/templates/Generators.kt
index 2fa21cb6394..967b3a017b9 100644
--- a/libraries/tools/kotlin-stdlib-gen/src/templates/Generators.kt
+++ b/libraries/tools/kotlin-stdlib-gen/src/templates/Generators.kt
@@ -119,7 +119,7 @@ fun generators(): List<GenericFunction> {
     }
 
     templates add f("merge(other: Iterable<R>, transform: (T, R) -> V)") {
-        exclude(Streams)
+        exclude(Streams, Strings)
         doc {
             """
             Returns a list of values built from elements of both collections with same indexes using provided *transform*. List has length of shortest collection.
@@ -133,7 +133,18 @@ fun generators(): List<GenericFunction> {
             """
             val first = iterator()
             val second = other.iterator()
-            val list = arrayListOf<V>()
+            val list = ArrayList<V>(collectionSizeOrDefault(10))
+            while (first.hasNext() && second.hasNext()) {
+                list.add(transform(first.next(), second.next()))
+            }
+            return list
+            """
+        }
+        body(ArraysOfObjects, ArraysOfPrimitives) {
+            """
+            val first = iterator()
+            val second = other.iterator()
+            val list = ArrayList<V>(size())
             while (first.hasNext() && second.hasNext()) {
                 list.add(transform(first.next(), second.next()))
             }
@@ -143,7 +154,7 @@ fun generators(): List<GenericFunction> {
     }
 
     templates add f("merge(array: Array<out R>, transform: (T, R) -> V)") {
-        exclude(Streams)
+        exclude(Streams, Strings)
         doc {
             """
             Returns a list of values built from elements of both collections with same indexes using provided *transform*. List has length of shortest collection.
@@ -157,13 +168,25 @@ fun generators(): List<GenericFunction> {
             """
             val first = iterator()
             val second = array.iterator()
-            val list = arrayListOf<V>()
+            val list = ArrayList<V>(collectionSizeOrDefault(10))
             while (first.hasNext() && second.hasNext()) {
                 list.add(transform(first.next(), second.next()))
             }
             return list
             """
         }
+        body(ArraysOfObjects, ArraysOfPrimitives) {
+            """
+            val first = iterator()
+            val second = array.iterator()
+            val list = ArrayList<V>(size())
+            while (first.hasNext() && second.hasNext()) {
+                list.add(transform(first.next(), second.next()))
+            }
+            return list
+            """
+        }
+
     }
 
 
@@ -186,7 +209,7 @@ fun generators(): List<GenericFunction> {
 
 
     templates add f("zip(other: Iterable<R>)") {
-        exclude(Streams)
+        exclude(Streams, Strings)
         doc {
             """
             Returns a list of pairs built from elements of both collections with same indexes. List has length of shortest collection.
@@ -213,7 +236,7 @@ fun generators(): List<GenericFunction> {
             """
             val first = iterator()
             val second = other.iterator()
-            val list = ArrayList<Pair<Char, Char>>()
+            val list = ArrayList<Pair<Char, Char>>(length())
             while (first.hasNext() && second.hasNext()) {
                 list.add(first.next() to second.next())
             }
@@ -223,7 +246,7 @@ fun generators(): List<GenericFunction> {
     }
 
     templates add f("zip(array: Array<out R>)") {
-        exclude(Streams)
+        exclude(Streams, Strings)
         doc {
             """
             Returns a list of pairs built from elements of both collections with same indexes. List has length of shortest collection.
diff --git a/libraries/tools/kotlin-stdlib-gen/src/templates/Mapping.kt b/libraries/tools/kotlin-stdlib-gen/src/templates/Mapping.kt
index 1e14918f48c..266815fa57c 100644
--- a/libraries/tools/kotlin-stdlib-gen/src/templates/Mapping.kt
+++ b/libraries/tools/kotlin-stdlib-gen/src/templates/Mapping.kt
@@ -51,9 +51,14 @@ fun mapping(): List<GenericFunction> {
         typeParam("R")
         returns("List<R>")
         body {
-            "return mapIndexedTo(ArrayList<R>(), transform)"
+            "return mapIndexedTo(ArrayList<R>(collectionSizeOrDefault(10)), transform)"
+        }
+        body(ArraysOfObjects, ArraysOfPrimitives) {
+            "return mapIndexedTo(ArrayList<R>(size()), transform)"
+        }
+        body(Strings) {
+            "return mapIndexedTo(ArrayList<R>(length()), transform)"
         }
-
         inline(false, Streams)
         returns(Streams) { "Stream<R>" }
         doc(Streams) { "Returns a stream containing the results of applying the given *transform* function to each element and its index of the original stream" }
diff --git a/libraries/tools/kotlin-stdlib-gen/src/templates/Snapshots.kt b/libraries/tools/kotlin-stdlib-gen/src/templates/Snapshots.kt
index f9da0307009..05b85b4787c 100644
--- a/libraries/tools/kotlin-stdlib-gen/src/templates/Snapshots.kt
+++ b/libraries/tools/kotlin-stdlib-gen/src/templates/Snapshots.kt
@@ -40,16 +40,9 @@ fun snapshots(): List<GenericFunction> {
     templates add f("toArrayList()") {
         doc { "Returns an ArrayList of all elements" }
         returns("ArrayList<T>")
-        body { "return toCollection(ArrayList<T>())" }
-
-        // ISSUE: JavaScript can't perform this operation
-        /*
-                body(Collections) {
-                    """
-                    return ArrayList<T>(this)
-                    """
-                }
-        */
+        body { "return toCollection(ArrayList<T>(collectionSizeOrDefault(10)))" }
+        body(Streams) { "return toCollection(ArrayList<T>())" }
+        body(Strings) { "return toCollection(ArrayList<T>(length()))" }
         body(ArraysOfObjects, ArraysOfPrimitives) {
             """
             val list = ArrayList<T>(size())
@@ -76,22 +69,10 @@ fun snapshots(): List<GenericFunction> {
     templates add f("toList()") {
         doc { "Returns a List containing all elements" }
         returns("List<T>")
-        body { "return toCollection(ArrayList<T>())" }
-
-        // ISSUE: JavaScript can't perform this operations
-        /*
-                body(Collections) {
-                    """
-                    return ArrayList<T>(this)
-                    """
-                }
-                body(ArraysOfObjects) {
-                    """
-                    return ArrayList<T>(Arrays.asList(*this))
-                    """
-                }
-        */
-        body(ArraysOfPrimitives) {
+        body { "return toCollection(ArrayList<T>(collectionSizeOrDefault(10)))" }
+        body(Streams) { "return toCollection(ArrayList<T>())" }
+        body(Strings) { "return toCollection(ArrayList<T>(length()))" }
+        body(ArraysOfObjects, ArraysOfPrimitives) {
             """
             val list = ArrayList<T>(size())
             for (item in this) list.add(item)