Sorted range methods

Author: lrytz

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

@@ -48,6 +48,12 @@ package object compat {
     def lazyAppendAll(as: => TraversableOnce[A]): Stream[A] = stream.append(as)
   }
 
+  implicit class SortedExtensionMethods[K, T <: Sorted[K, T]](private val fact: Sorted[K, T]) {
+    def rangeFrom(from: K): T = fact.from(from)
+    def rangeTo(to: K): T = fact.to(to)
+    def rangeUntil(until: K): T = fact.until(until)
+  }
+
   // This really belongs into scala.collection but there's already a package object in scala-library so we can't add to it
   type IterableOnce[+X] = TraversableOnce[X]
 }

src/test/scala/scala/collection/generic/SortedTest.scala

@@ -0,0 +1,53 @@
+package scala.collection.generic
+
+import org.junit.Test
+import org.junit.Assert._
+
+import scala.collection.compat._
+import scala.collection.{immutable => i, mutable => m}
+
+class SortedTest {
+  @Test
+  def immutableRangeOps(): Unit = {
+    val st = i.SortedSet(-1, 2, 4, 3)
+    for (x <- List(0, 1, 4, -1, -4)) {
+      val s1 = st.rangeFrom(x)
+      assertEquals(s1: i.SortedSet[Int], st.from(x))
+      val s2 = st.rangeTo(x)
+      assertEquals(s2: i.SortedSet[Int], st.to(x))
+      val s3 = st.rangeUntil(x)
+      assertEquals(s3: i.SortedSet[Int], st.until(x))
+    }
+    val mp = i.SortedMap("" -> 0, "ds" -> -3, "-??" -> 13, "Df" -> 33, "d!" -> -32)
+    for (x <- List("", "-", "@", "aa", "D", "d")) {
+      val m1 = mp.rangeFrom(x)
+      assertEquals(m1: i.SortedMap[String, Int], mp.from(x))
+      val m2 = mp.rangeTo(x)
+      assertEquals(m2: i.SortedMap[String, Int], mp.to(x))
+      val m3 = mp.rangeUntil(x)
+      assertEquals(m3: i.SortedMap[String, Int], mp.until(x))
+    }
+  }
+
+  @Test
+  def mutableRangeOps(): Unit = {
+    val st = m.SortedSet(-1, 2, 4, 3)
+    for (x <- List(0, 1, 4, -1, -4)) {
+      val s1 = st.rangeFrom(x)
+      assertEquals(s1: m.SortedSet[Int], st.from(x))
+      val s2 = st.rangeTo(x)
+      assertEquals(s2: m.SortedSet[Int], st.to(x))
+      val s3 = st.rangeUntil(x)
+      assertEquals(s3: m.SortedSet[Int], st.until(x))
+    }
+    val mp = m.SortedMap("" -> 0, "ds" -> -3, "-??" -> 13, "Df" -> 33, "d!" -> -32)
+    for (x <- List("", "-", "@", "aa", "D", "d")) {
+      val m1 = mp.rangeFrom(x)
+      assertEquals(m1: m.SortedMap[String, Int], mp.from(x))
+      val m2 = mp.rangeTo(x)
+      assertEquals(m2: m.SortedMap[String, Int], mp.to(x))
+      val m3 = mp.rangeUntil(x)
+      assertEquals(m3: m.SortedMap[String, Int], mp.until(x))
+    }
+  }
+}