add Random.nextLong(Long)

Author: xuwei-k

compat/src/main/scala-2.11_2.12/scala/collection/compat/PackageShared.scala

@@ -25,6 +25,7 @@ import scala.collection.{
   mutable => m
 }
 import scala.runtime.{Tuple2Zipped, Tuple3Zipped}
+import scala.util.Random
 import scala.{collection => c}
 
 /** The collection compatibility API */
@@ -351,6 +352,9 @@ private[compat] trait PackageShared {
 
   implicit def toOptionCompanionExtension(fact: Option.type): OptionCompanionExtensionMethods =
     new OptionCompanionExtensionMethods(fact)
+
+  implicit def toRandomExtensions(self: Random): RandomExtensions =
+    new RandomExtensions(self)
 }
 
 class ImmutableSortedMapExtensions(private val fact: i.SortedMap.type) extends AnyVal {

compat/src/main/scala-2.11_2.12/scala/collection/compat/RandomExtensions.scala

@@ -0,0 +1,36 @@
+/*
+ * Scala (https://www.scala-lang.org)
+ *
+ * Copyright EPFL and Lightbend, Inc.
+ *
+ * Licensed under Apache License 2.0
+ * (http://www.apache.org/licenses/LICENSE-2.0).
+ *
+ * See the NOTICE file distributed with this work for
+ * additional information regarding copyright ownership.
+ */
+
+package scala.collection.compat
+
+import scala.util.Random
+
+final class RandomExtensions(private val self: Random) extends AnyVal {
+  def nextLong(n: Long): Long = {
+    require(n > 0, "n must be positive")
+
+    var offset = 0L
+    var _n = n
+
+    while (_n >= Integer.MAX_VALUE) {
+      val bits = self.nextInt(2)
+      val halfn = _n >>> 1
+      val nextn =
+        if ((bits & 2) == 0) halfn
+        else _n - halfn
+      if ((bits & 1) == 0)
+        offset += _n - nextn
+      _n = nextn
+    }
+    offset + self.nextInt(_n.toInt)
+  }
+}

compat/src/test/scala/test/scala/util/RandomTest.scala

@@ -0,0 +1,34 @@
+/*
+ * Scala (https://www.scala-lang.org)
+ *
+ * Copyright EPFL and Lightbend, Inc.
+ *
+ * Licensed under Apache License 2.0
+ * (http://www.apache.org/licenses/LICENSE-2.0).
+ *
+ * See the NOTICE file distributed with this work for
+ * additional information regarding copyright ownership.
+ */
+
+package test.scala.util
+
+import org.junit.Assert._
+import org.junit.Test
+import scala.collection.compat._
+import scala.util.Random
+import test.scala.collection.AssertThrown
+
+class RandomTest extends AssertThrown {
+  @Test
+  def nextLong(): Unit = {
+    val rand = new Random(12345)
+
+    assertEquals(4896762128577075113L, rand.nextLong(Long.MaxValue))
+    assertEquals(2005076556L, rand.nextLong(Int.MaxValue))
+    assertEquals(0L, rand.nextLong(1L))
+
+    assertThrows[IllegalArgumentException](rand.nextLong(0L))
+    assertThrows[IllegalArgumentException](rand.nextLong(-2L))
+    assertThrows[IllegalArgumentException](rand.nextLong(Long.MinValue))
+  }
+}