Add samples for Iterables #KT-20357

libraries/stdlib/samples/test/samples/collections/iterables.kt

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2010-2017 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 samples.collections
+
+import samples.*
+import kotlin.coroutines.experimental.buildIterator
+import kotlin.test.*
+
+class Iterables {
+
+    @Sample
+    fun iterable() {
+        val iterable = Iterable { buildIterator { yieldAll(1..3) } }
+        val result = iterable.mapIndexed { index, i -> index + i }
+        assertPrints(result, "[1, 3, 5]")
+    }
+
+    @Sample
+    fun flattenIterable() {
+        val deepList = listOf(listOf(1), listOf(2, 3), listOf(4, 5, 6))
+        assertPrints(deepList.flatten(), "[1, 2, 3, 4, 5, 6]")
+    }
+
+    @Sample
+    fun unzipIterable() {
+        val list = listOf(1 to 'a', 2 to 'b', 3 to 'c')
+        assertPrints(list.unzip(), "([1, 2, 3], [a, b, c])")
+    }
+}

libraries/stdlib/src/kotlin/collections/Iterables.kt

@@ -20,6 +20,7 @@ package kotlin.collections
 /**
  * Given an [iterator] function constructs an [Iterable] instance that returns values through the [Iterator]
  * provided by that function.
+ * @sample samples.collections.Iterables.iterable
  */
 @kotlin.internal.InlineOnly
 public inline fun <T> Iterable(crossinline iterator: () -> Iterator<T>): Iterable<T> = object : Iterable<T> {
@@ -73,6 +74,7 @@ internal fun <T> Iterable<T>.convertToSetForSetOperation(): Collection<T> =
 
 /**
  * Returns a single list of all elements from all collections in the given collection.
+ * @sample samples.collections.Iterables.flattenIterable
  */
 public fun <T> Iterable<Iterable<T>>.flatten(): List<T> {
     val result = ArrayList<T>()
@@ -86,6 +88,7 @@ public fun <T> Iterable<Iterable<T>>.flatten(): List<T> {
  * Returns a pair of lists, where
  * *first* list is built from the first values of each pair from this collection,
  * *second* list is built from the second values of each pair from this collection.
+ * @sample samples.collections.Iterables.unzipIterable
  */
 public fun <T, R> Iterable<Pair<T, R>>.unzip(): Pair<List<T>, List<R>> {
     val expectedSize = collectionSizeOrDefault(10)