Extension random() to select random element from a collection

Fixes #KT-15539

libraries/stdlib/common/src/generated/_Arrays.kt

@@ -16,6 +16,7 @@ package kotlin.collections
 import kotlin.*
 import kotlin.text.*
 import kotlin.comparisons.*
+import kotlin.random.*
 
 /**
  * Returns 1st *element* from the collection.
@@ -2049,6 +2050,213 @@ public inline fun CharArray.lastOrNull(predicate: (Char) -> Boolean): Char? {
     return null
 }
 
+/**
+ * Returns a random element from this array.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@kotlin.internal.InlineOnly
+public inline fun <T> Array<out T>.random(): T {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this array.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@kotlin.internal.InlineOnly
+public inline fun ByteArray.random(): Byte {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this array.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@kotlin.internal.InlineOnly
+public inline fun ShortArray.random(): Short {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this array.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@kotlin.internal.InlineOnly
+public inline fun IntArray.random(): Int {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this array.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@kotlin.internal.InlineOnly
+public inline fun LongArray.random(): Long {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this array.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@kotlin.internal.InlineOnly
+public inline fun FloatArray.random(): Float {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this array.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@kotlin.internal.InlineOnly
+public inline fun DoubleArray.random(): Double {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this array.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@kotlin.internal.InlineOnly
+public inline fun BooleanArray.random(): Boolean {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this array.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@kotlin.internal.InlineOnly
+public inline fun CharArray.random(): Char {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this array using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+public fun <T> Array<out T>.random(random: Random): T {
+    if (isEmpty())
+        throw NoSuchElementException("Array is empty.")
+    return get(random.nextInt(size))
+}
+
+/**
+ * Returns a random element from this array using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+public fun ByteArray.random(random: Random): Byte {
+    if (isEmpty())
+        throw NoSuchElementException("Array is empty.")
+    return get(random.nextInt(size))
+}
+
+/**
+ * Returns a random element from this array using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+public fun ShortArray.random(random: Random): Short {
+    if (isEmpty())
+        throw NoSuchElementException("Array is empty.")
+    return get(random.nextInt(size))
+}
+
+/**
+ * Returns a random element from this array using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+public fun IntArray.random(random: Random): Int {
+    if (isEmpty())
+        throw NoSuchElementException("Array is empty.")
+    return get(random.nextInt(size))
+}
+
+/**
+ * Returns a random element from this array using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+public fun LongArray.random(random: Random): Long {
+    if (isEmpty())
+        throw NoSuchElementException("Array is empty.")
+    return get(random.nextInt(size))
+}
+
+/**
+ * Returns a random element from this array using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+public fun FloatArray.random(random: Random): Float {
+    if (isEmpty())
+        throw NoSuchElementException("Array is empty.")
+    return get(random.nextInt(size))
+}
+
+/**
+ * Returns a random element from this array using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+public fun DoubleArray.random(random: Random): Double {
+    if (isEmpty())
+        throw NoSuchElementException("Array is empty.")
+    return get(random.nextInt(size))
+}
+
+/**
+ * Returns a random element from this array using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+public fun BooleanArray.random(random: Random): Boolean {
+    if (isEmpty())
+        throw NoSuchElementException("Array is empty.")
+    return get(random.nextInt(size))
+}
+
+/**
+ * Returns a random element from this array using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+public fun CharArray.random(random: Random): Char {
+    if (isEmpty())
+        throw NoSuchElementException("Array is empty.")
+    return get(random.nextInt(size))
+}
+
 /**
  * Returns the single element, or throws an exception if the array is empty or has more than one element.
  */

libraries/stdlib/common/src/generated/_Collections.kt

@@ -16,6 +16,7 @@ package kotlin.collections
 import kotlin.*
 import kotlin.text.*
 import kotlin.comparisons.*
+import kotlin.random.*
 
 /**
  * Returns 1st *element* from the collection.
@@ -456,6 +457,29 @@ public inline fun <T> List<T>.lastOrNull(predicate: (T) -> Boolean): T? {
     return null
 }
 
+/**
+ * Returns a random element from this collection.
+ * 
+ * @throws NoSuchElementException if this collection is empty.
+ */
+@SinceKotlin("1.3")
+@kotlin.internal.InlineOnly
+public inline fun <T> Collection<T>.random(): T {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this collection using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this collection is empty.
+ */
+@SinceKotlin("1.3")
+public fun <T> Collection<T>.random(random: Random): T {
+    if (isEmpty())
+        throw NoSuchElementException("Collection is empty.")
+    return elementAt(random.nextInt(size))
+}
+
 /**
  * Returns the single element, or throws an exception if the collection is empty or has more than one element.
  */

libraries/stdlib/common/src/generated/_Comparisons.kt

@@ -16,6 +16,7 @@ package kotlin.comparisons
 import kotlin.*
 import kotlin.text.*
 import kotlin.comparisons.*
+import kotlin.random.*
 
 /**
  * Returns the greater of two values.

libraries/stdlib/common/src/generated/_Maps.kt

@@ -16,6 +16,7 @@ package kotlin.collections
 import kotlin.*
 import kotlin.text.*
 import kotlin.comparisons.*
+import kotlin.random.*
 
 /**
  * Returns a [List] containing all key-value pairs.

libraries/stdlib/common/src/generated/_Ranges.kt

@@ -16,6 +16,70 @@ package kotlin.ranges
 import kotlin.*
 import kotlin.text.*
 import kotlin.comparisons.*
+import kotlin.random.*
+
+/**
+ * Returns a random element from this range.
+ * 
+ * @throws IllegalArgumentException if this range is empty.
+ */
+@SinceKotlin("1.3")
+@kotlin.internal.InlineOnly
+public inline fun IntRange.random(): Int {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this range.
+ * 
+ * @throws IllegalArgumentException if this range is empty.
+ */
+@SinceKotlin("1.3")
+@kotlin.internal.InlineOnly
+public inline fun LongRange.random(): Long {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this range.
+ * 
+ * @throws IllegalArgumentException if this range is empty.
+ */
+@SinceKotlin("1.3")
+@kotlin.internal.InlineOnly
+public inline fun CharRange.random(): Char {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this range using the specified source of randomness.
+ * 
+ * @throws IllegalArgumentException if this range is empty.
+ */
+@SinceKotlin("1.3")
+public fun IntRange.random(random: Random): Int {
+    return random.nextInt(this)
+}
+
+/**
+ * Returns a random element from this range using the specified source of randomness.
+ * 
+ * @throws IllegalArgumentException if this range is empty.
+ */
+@SinceKotlin("1.3")
+public fun LongRange.random(random: Random): Long {
+    return random.nextLong(this)
+}
+
+/**
+ * Returns a random element from this range using the specified source of randomness.
+ * 
+ * @throws IllegalArgumentException if this range is empty.
+ */
+@SinceKotlin("1.3")
+public fun CharRange.random(random: Random): Char {
+    return random.nextInt(first.toInt(), last.toInt() + 1).toChar()
+}
 
 /**
  * Checks if the specified [value] belongs to this range.

libraries/stdlib/common/src/generated/_Sequences.kt

@@ -16,6 +16,7 @@ package kotlin.sequences
 import kotlin.*
 import kotlin.text.*
 import kotlin.comparisons.*
+import kotlin.random.*
 import kotlin.coroutines.experimental.*
 
 /**

libraries/stdlib/common/src/generated/_Sets.kt

@@ -16,6 +16,7 @@ package kotlin.collections
 import kotlin.*
 import kotlin.text.*
 import kotlin.comparisons.*
+import kotlin.random.*
 
 /**
  * Returns a set containing all elements of the original set except the given [element].

libraries/stdlib/common/src/generated/_Strings.kt

@@ -16,6 +16,7 @@ package kotlin.text
 import kotlin.*
 import kotlin.text.*
 import kotlin.comparisons.*
+import kotlin.random.*
 
 /**
  * Returns a character at the given [index] or throws an [IndexOutOfBoundsException] if the [index] is out of bounds of this char sequence.
@@ -170,6 +171,29 @@ public inline fun CharSequence.lastOrNull(predicate: (Char) -> Boolean): Char? {
     return null
 }
 
+/**
+ * Returns a random character from this char sequence.
+ * 
+ * @throws NoSuchElementException if this char sequence is empty.
+ */
+@SinceKotlin("1.3")
+@kotlin.internal.InlineOnly
+public inline fun CharSequence.random(): Char {
+    return random(Random)
+}
+
+/**
+ * Returns a random character from this char sequence using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this char sequence is empty.
+ */
+@SinceKotlin("1.3")
+public fun CharSequence.random(random: Random): Char {
+    if (isEmpty())
+        throw NoSuchElementException("Char sequence is empty.")
+    return get(random.nextInt(length))
+}
+
 /**
  * Returns the single character, or throws an exception if the char sequence is empty or has more than one character.
  */

libraries/stdlib/common/src/generated/_UArrays.kt

@@ -16,6 +16,107 @@ package kotlin.collections
 import kotlin.*
 import kotlin.text.*
 import kotlin.comparisons.*
+import kotlin.random.*
+
+/**
+ * Returns a random element from this array.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@ExperimentalUnsignedTypes
+@kotlin.internal.InlineOnly
+public inline fun UIntArray.random(): UInt {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this array.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@ExperimentalUnsignedTypes
+@kotlin.internal.InlineOnly
+public inline fun ULongArray.random(): ULong {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this array.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@ExperimentalUnsignedTypes
+@kotlin.internal.InlineOnly
+public inline fun UByteArray.random(): UByte {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this array.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@ExperimentalUnsignedTypes
+@kotlin.internal.InlineOnly
+public inline fun UShortArray.random(): UShort {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this array using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@ExperimentalUnsignedTypes
+public fun UIntArray.random(random: Random): UInt {
+    if (isEmpty())
+        throw NoSuchElementException("Array is empty.")
+    return get(random.nextInt(size))
+}
+
+/**
+ * Returns a random element from this array using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@ExperimentalUnsignedTypes
+public fun ULongArray.random(random: Random): ULong {
+    if (isEmpty())
+        throw NoSuchElementException("Array is empty.")
+    return get(random.nextInt(size))
+}
+
+/**
+ * Returns a random element from this array using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@ExperimentalUnsignedTypes
+public fun UByteArray.random(random: Random): UByte {
+    if (isEmpty())
+        throw NoSuchElementException("Array is empty.")
+    return get(random.nextInt(size))
+}
+
+/**
+ * Returns a random element from this array using the specified source of randomness.
+ * 
+ * @throws NoSuchElementException if this array is empty.
+ */
+@SinceKotlin("1.3")
+@ExperimentalUnsignedTypes
+public fun UShortArray.random(random: Random): UShort {
+    if (isEmpty())
+        throw NoSuchElementException("Array is empty.")
+    return get(random.nextInt(size))
+}
 
 /**
  * Returns an array of type [ByteArray], which is a view of this array where each element is a signed reinterpretation

libraries/stdlib/common/src/generated/_URanges.kt

@@ -16,6 +16,53 @@ package kotlin.ranges
 import kotlin.*
 import kotlin.text.*
 import kotlin.comparisons.*
+import kotlin.random.*
+
+/**
+ * Returns a random element from this range.
+ * 
+ * @throws IllegalArgumentException if this range is empty.
+ */
+@SinceKotlin("1.3")
+@ExperimentalUnsignedTypes
+@kotlin.internal.InlineOnly
+public inline fun UIntRange.random(): UInt {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this range.
+ * 
+ * @throws IllegalArgumentException if this range is empty.
+ */
+@SinceKotlin("1.3")
+@ExperimentalUnsignedTypes
+@kotlin.internal.InlineOnly
+public inline fun ULongRange.random(): ULong {
+    return random(Random)
+}
+
+/**
+ * Returns a random element from this range using the specified source of randomness.
+ * 
+ * @throws IllegalArgumentException if this range is empty.
+ */
+@SinceKotlin("1.3")
+@ExperimentalUnsignedTypes
+public fun UIntRange.random(random: Random): UInt {
+    return random.nextUInt(this)
+}
+
+/**
+ * Returns a random element from this range using the specified source of randomness.
+ * 
+ * @throws IllegalArgumentException if this range is empty.
+ */
+@SinceKotlin("1.3")
+@ExperimentalUnsignedTypes
+public fun ULongRange.random(random: Random): ULong {
+    return random.nextULong(this)
+}
 
 /**
  * Returns a progression from this value down to the specified [to] value with the step -1.

libraries/stdlib/test/collections/ArraysTest.kt

@@ -11,6 +11,7 @@ import test.collections.behaviors.*
 import test.comparisons.STRING_CASE_INSENSITIVE_ORDER
 import kotlin.test.*
 import kotlin.comparisons.*
+import kotlin.random.Random
 
 fun <T> assertArrayNotSameButEquals(expected: Array<out T>, actual: Array<out T>, message: String = "") { assertTrue(expected !== actual && expected contentEquals actual, message) }
 fun assertArrayNotSameButEquals(expected: IntArray, actual: IntArray, message: String = "") {             assertTrue(expected !== actual && expected contentEquals actual, message) }
@@ -592,6 +593,31 @@ class ArraysTest {
         expect(2) { arrayOf(1, 2, 3).last { it % 2 == 0 } }
     }
 
+
+    @Test fun random() {
+        Array(100) { it }.let { array ->
+            val tosses = List(10) { array.random() }
+            assertTrue(tosses.distinct().size > 1, "Should be some distinct elements in $tosses")
+
+            val seed = Random.nextInt()
+            val random1 = Random(seed)
+            val random2 = Random(seed)
+
+            val tosses1 = List(10) { array.random(random1) }
+            val tosses2 = List(10) { array.random(random2) }
+
+            assertEquals(tosses1, tosses2)
+        }
+
+        arrayOf("x").let { singletonArray ->
+            val tosses = List(10) { singletonArray.random() }
+            assertEquals(singletonArray.toList(), tosses.distinct())
+        }
+
+        assertFailsWith<NoSuchElementException> { emptyArray<Any>().random() }
+    }
+
+
     @Test fun contains() {
         assertTrue(arrayOf("1", "2", "3", "4").contains("2"))
         assertTrue("3" in arrayOf("1", "2", "3", "4"))

libraries/stdlib/test/collections/CollectionTest.kt

@@ -10,6 +10,8 @@ import kotlin.test.*
 import test.collections.behaviors.*
 import test.comparisons.STRING_CASE_INSENSITIVE_ORDER
 import kotlin.comparisons.*
+import kotlin.math.sin
+import kotlin.random.Random
 
 class CollectionTest {
 
@@ -620,6 +622,31 @@ class CollectionTest {
         assertFails { arrayListOf<Int>().last() }
     }
 
+    @Test fun random() {
+        val list = List(100) { it }
+        val set = list.toSet()
+        listOf(list, set).forEach { collection: Collection<Int> ->
+            val tosses = List(10) { collection.random() }
+            assertTrue(tosses.distinct().size > 1, "Should be some distinct elements in $tosses")
+
+            val seed = Random.nextInt()
+            val random1 = Random(seed)
+            val random2 = Random(seed)
+
+            val tosses1 = List(10) { collection.random(random1) }
+            val tosses2 = List(10) { collection.random(random2) }
+
+            assertEquals(tosses1, tosses2)
+        }
+
+        listOf("x").let { singletonList ->
+            val tosses = List(10) { singletonList.random() }
+            assertEquals(singletonList, tosses.distinct())
+        }
+
+        assertFailsWith<NoSuchElementException> { emptyList<Any>().random() }
+    }
+
     @Test fun subscript() {
         val list = arrayListOf("foo", "bar")
         assertEquals("foo", list[0])

libraries/stdlib/test/text/StringTest.kt

@@ -10,6 +10,7 @@ import test.*
 import test.collections.behaviors.iteratorBehavior
 import test.collections.compare
 import kotlin.math.sign
+import kotlin.random.Random
 
 
 fun createString(content: String): CharSequence = content
@@ -936,6 +937,29 @@ class StringTest {
         assertNull(data.filterNot { it.isAsciiLetter() || it.isAsciiDigit() }.firstOrNull())
     }
 
+    @Test fun random() = withOneCharSequenceArg { data ->
+        data("abcdefg").let { charSeq ->
+            val tosses = List(10) { charSeq.random() }
+            assertTrue(tosses.distinct().size > 1, "Should be some distinct elements in $tosses")
+
+            val seed = Random.nextInt()
+            val random1 = Random(seed)
+            val random2 = Random(seed)
+
+            val tosses1 = List(10) { charSeq.random(random1) }
+            val tosses2 = List(10) { charSeq.random(random2) }
+
+            assertEquals(tosses1, tosses2)
+        }
+
+        data("x").let { singletonCharSeq ->
+            val tosses = List(10) { singletonCharSeq.random() }
+            assertEquals(singletonCharSeq.toList(), tosses.distinct())
+        }
+
+        assertFailsWith<NoSuchElementException> { data("").random() }
+    }
+
     @Test fun partition() {
         val data = "a1b2c3"
         val pair = data.partition { it.isAsciiDigit() }

libraries/tools/binary-compatibility-validator/reference-public-api/kotlin-stdlib-runtime-merged.txt

@@ -1604,6 +1604,15 @@ public final class kotlin/collections/ArraysKt {
 	public static final fun plus ([ZLjava/util/Collection;)[Z
 	public static final fun plus ([ZZ)[Z
 	public static final fun plus ([Z[Z)[Z
+	public static final fun random ([BLkotlin/random/Random;)B
+	public static final fun random ([CLkotlin/random/Random;)C
+	public static final fun random ([DLkotlin/random/Random;)D
+	public static final fun random ([FLkotlin/random/Random;)F
+	public static final fun random ([ILkotlin/random/Random;)I
+	public static final fun random ([JLkotlin/random/Random;)J
+	public static final fun random ([Ljava/lang/Object;Lkotlin/random/Random;)Ljava/lang/Object;
+	public static final fun random ([SLkotlin/random/Random;)S
+	public static final fun random ([ZLkotlin/random/Random;)Z
 	public static final fun reduce ([BLkotlin/jvm/functions/Function2;)B
 	public static final fun reduce ([CLkotlin/jvm/functions/Function2;)C
 	public static final fun reduce ([DLkotlin/jvm/functions/Function2;)D
@@ -2234,6 +2243,7 @@ public final class kotlin/collections/CollectionsKt {
 	public static final fun plus (Ljava/util/Collection;Ljava/lang/Object;)Ljava/util/List;
 	public static final fun plus (Ljava/util/Collection;Lkotlin/sequences/Sequence;)Ljava/util/List;
 	public static final fun plus (Ljava/util/Collection;[Ljava/lang/Object;)Ljava/util/List;
+	public static final fun random (Ljava/util/Collection;Lkotlin/random/Random;)Ljava/lang/Object;
 	public static final fun reduce (Ljava/lang/Iterable;Lkotlin/jvm/functions/Function2;)Ljava/lang/Object;
 	public static final fun reduceIndexed (Ljava/lang/Iterable;Lkotlin/jvm/functions/Function3;)Ljava/lang/Object;
 	public static final fun reduceRight (Ljava/util/List;Lkotlin/jvm/functions/Function2;)Ljava/lang/Object;
@@ -2493,6 +2503,10 @@ public final class kotlin/collections/UArraysKt {
 	public static final fun contentToString-3o8tnvbt ([J)Ljava/lang/String;
 	public static final fun contentToString-9gu3s6ig ([S)Ljava/lang/String;
 	public static final fun contentToString-doljm8k0 ([I)Ljava/lang/String;
+	public static final fun random-25eqzsg0 ([JLkotlin/random/Random;)J
+	public static final fun random-8tx9e8n3 ([BLkotlin/random/Random;)B
+	public static final fun random-9uc5g3in ([SLkotlin/random/Random;)S
+	public static final fun random-bunzpqo3 ([ILkotlin/random/Random;)I
 	public static final fun toTypedArray-1biuymyp ([B)[Lkotlin/UByte;
 	public static final fun toTypedArray-3o8tnvbt ([J)[Lkotlin/ULong;
 	public static final fun toTypedArray-9gu3s6ig ([S)[Lkotlin/UShort;
@@ -4125,6 +4139,9 @@ public final class kotlin/ranges/RangesKt {
 	public static final fun longRangeContains (Lkotlin/ranges/ClosedRange;F)Z
 	public static final fun longRangeContains (Lkotlin/ranges/ClosedRange;I)Z
 	public static final fun longRangeContains (Lkotlin/ranges/ClosedRange;S)Z
+	public static final fun random (Lkotlin/ranges/CharRange;Lkotlin/random/Random;)C
+	public static final fun random (Lkotlin/ranges/IntRange;Lkotlin/random/Random;)I
+	public static final fun random (Lkotlin/ranges/LongRange;Lkotlin/random/Random;)J
 	public static final fun rangeTo (DD)Lkotlin/ranges/ClosedFloatingPointRange;
 	public static final fun rangeTo (FF)Lkotlin/ranges/ClosedFloatingPointRange;
 	public static final fun rangeTo (Ljava/lang/Comparable;Ljava/lang/Comparable;)Lkotlin/ranges/ClosedRange;
@@ -4235,6 +4252,8 @@ public final class kotlin/ranges/URangesKt {
 	public static final fun downTo-2ccbonl2 (BB)Lkotlin/ranges/UIntProgression;
 	public static final fun downTo-6o7e3yo2 (JJ)Lkotlin/ranges/ULongProgression;
 	public static final fun downTo-cjsx449s (SS)Lkotlin/ranges/UIntProgression;
+	public static final fun random (Lkotlin/ranges/UIntRange;Lkotlin/random/Random;)I
+	public static final fun random (Lkotlin/ranges/ULongRange;Lkotlin/random/Random;)J
 	public static final fun reversed (Lkotlin/ranges/UIntProgression;)Lkotlin/ranges/UIntProgression;
 	public static final fun reversed (Lkotlin/ranges/ULongProgression;)Lkotlin/ranges/ULongProgression;
 	public static final fun step (Lkotlin/ranges/UIntProgression;I)Lkotlin/ranges/UIntProgression;
@@ -4934,6 +4953,7 @@ public final class kotlin/text/StringsKt {
 	public static final fun partition (Ljava/lang/String;Lkotlin/jvm/functions/Function1;)Lkotlin/Pair;
 	public static final fun prependIndent (Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;
 	public static synthetic fun prependIndent$default (Ljava/lang/String;Ljava/lang/String;ILjava/lang/Object;)Ljava/lang/String;
+	public static final fun random (Ljava/lang/CharSequence;Lkotlin/random/Random;)C
 	public static final fun reduce (Ljava/lang/CharSequence;Lkotlin/jvm/functions/Function2;)C
 	public static final fun reduceIndexed (Ljava/lang/CharSequence;Lkotlin/jvm/functions/Function3;)C
 	public static final fun reduceRight (Ljava/lang/CharSequence;Lkotlin/jvm/functions/Function2;)C

libraries/tools/kotlin-stdlib-gen/src/templates/Elements.kt

@@ -13,6 +13,17 @@ object Elements : TemplateGroupBase() {
     init {
         defaultBuilder {
             sequenceClassification(terminal)
+            specialFor(ArraysOfUnsigned) {
+                since("1.3")
+                annotation("@ExperimentalUnsignedTypes")
+            }
+            specialFor(RangesOfPrimitives) {
+                if (primitive in PrimitiveType.unsignedPrimitives) {
+                    since("1.3")
+                    annotation("@ExperimentalUnsignedTypes")
+                    sourceFile(SourceFile.URanges)
+                }
+            }
         }
     }
 
@@ -808,6 +819,69 @@ object Elements : TemplateGroupBase() {
         }
     }
 
+    val f_random = fn("random()") {
+        include(Collections, ArraysOfObjects, ArraysOfPrimitives, ArraysOfUnsigned, CharSequences, RangesOfPrimitives)
+    } builder {
+        since("1.3")
+        inlineOnly()
+        returns("T")
+        doc {
+            """
+            Returns a random ${f.element} from this ${f.collection}.
+
+            @throws ${if (f == RangesOfPrimitives) "IllegalArgumentException" else "NoSuchElementException"} if this ${f.collection} is empty.
+            """
+        }
+        body {
+            """return random(Random)"""
+        }
+    }
+
+    val f_random_random = fn("random(random: Random)") {
+        include(Collections, ArraysOfObjects, ArraysOfPrimitives, ArraysOfUnsigned, CharSequences, RangesOfPrimitives)
+    } builder {
+        since("1.3")
+        returns("T")
+        doc {
+            """
+            Returns a random ${f.element} from this ${f.collection} using the specified source of randomness.
+
+            @throws ${if (f == RangesOfPrimitives) "IllegalArgumentException" else "NoSuchElementException"} if this ${f.collection} is empty.
+            """
+        }
+        body {
+            """
+            if (isEmpty())
+                throw NoSuchElementException("${f.doc.collection.capitalize()} is empty.")
+            return elementAt(random.nextInt(size))
+            """
+        }
+        specialFor(ArraysOfObjects, ArraysOfPrimitives, ArraysOfUnsigned, CharSequences) {
+            body {
+                val size = if (family == CharSequences) "length" else "size"
+                """
+                if (isEmpty())
+                    throw NoSuchElementException("${f.doc.collection.capitalize()} is empty.")
+                return get(random.nextInt($size))
+                """
+            }
+        }
+        specialFor(Maps) {
+            body {
+                """return entries.random(random)"""
+            }
+        }
+        specialFor(RangesOfPrimitives) {
+            body {
+                val expr = when (primitive) {
+                    PrimitiveType.Char -> "nextInt(first.toInt(), last.toInt() + 1).toChar()"
+                    else -> "next$primitive(this)"
+                }
+                """return random.$expr"""
+            }
+        }
+    }
+
     val f_components = (1..5).map { n ->
         fn("component$n()") {
             include(Lists, ArraysOfObjects, ArraysOfPrimitives)

libraries/tools/kotlin-stdlib-gen/src/templates/Ranges.kt

@@ -10,7 +10,7 @@ import templates.PrimitiveType.Companion.maxByCapacity
 
 object RangeOps : TemplateGroupBase() {
 
-    private val rangePrimitives = setOf(PrimitiveType.Int, PrimitiveType.Long, PrimitiveType.Char, PrimitiveType.UInt, PrimitiveType.ULong)
+    private val rangePrimitives = PrimitiveType.rangePrimitives
     private fun rangeElementType(fromType: PrimitiveType, toType: PrimitiveType) =
         maxByCapacity(fromType, toType).let {
             when {

libraries/tools/kotlin-stdlib-gen/src/templates/dsl/CommonTypes.kt

@@ -60,6 +60,7 @@ enum class PrimitiveType {
         val defaultPrimitives = PrimitiveType.values().toSet() - unsignedPrimitives
         val numericPrimitives = setOf(Int, Long, Byte, Short, Double, Float)
         val integralPrimitives = setOf(Int, Long, Byte, Short, Char)
+        val rangePrimitives = setOf(Int, Long, Char, UInt, ULong)
 
         val descendingByDomainCapacity = listOf(Double, Float, Long, Int, Short, Char, Byte)
         val descendingByDomainCapacityUnsigned = listOf(ULong, UInt, UShort, UByte)

libraries/tools/kotlin-stdlib-gen/src/templates/dsl/FamilyProperties.kt

@@ -32,8 +32,9 @@ object DocExtensions {
     val Family.collection: String
         get() = when (this) {
             CharSequences -> "char sequence"
-            ArraysOfObjects, ArraysOfPrimitives, InvariantArraysOfObjects -> "array"
+            ArraysOfObjects, ArraysOfPrimitives, InvariantArraysOfObjects, ArraysOfUnsigned -> "array"
-            Strings, Sequences, Maps, Lists, Sets, Ranges -> name.singularize().decapitalize()
+            Ranges, RangesOfPrimitives -> "range"
+            Strings, Sequences, Maps, Lists, Sets -> name.singularize().decapitalize()
             else -> "collection"
         }
 

libraries/tools/kotlin-stdlib-gen/src/templates/dsl/Templates.kt

@@ -149,6 +149,7 @@ abstract class MemberTemplateDefinition<TParam> : MemberTemplate {
 private fun defaultPrimitives(f: Family): Set<PrimitiveType> =
     when {
         f == Family.Unsigned || f == Family.ArraysOfUnsigned -> PrimitiveType.unsignedPrimitives
+        f == Family.RangesOfPrimitives -> PrimitiveType.rangePrimitives
         f.isPrimitiveSpecialization -> PrimitiveType.defaultPrimitives
         else -> emptySet()
     }

libraries/tools/kotlin-stdlib-gen/src/templates/dsl/Writers.kt

@@ -92,6 +92,9 @@ fun List<MemberBuilder>.writeTo(file: File, platformSource: PlatformSourceFile)
         writer.appendln("import kotlin.*")
         writer.appendln("import kotlin.text.*")
         writer.appendln("import kotlin.comparisons.*")
+        if (platform == Platform.Common) {
+            writer.appendln("import kotlin.random.*")
+        }
 
         if (sourceFile == SourceFile.Sequences) {
             writer.appendln("import kotlin.coroutines.experimental.*")