Support Yield.From in functions that return SeqView for Scala 2.11 an…

…d 2.13
ThoughtWorksInc · Jan 29, 2020 · acd1a4b · acd1a4b
1 parent f5406c6
commit acd1a4b
Show file tree

Hide file tree

Showing 2 changed files with 50 additions and 4 deletions.
diff --git a/keywords-Yield/src/main/scala/com/thoughtworks/dsl/keywords/Yield.scala b/keywords-Yield/src/main/scala/com/thoughtworks/dsl/keywords/Yield.scala
@@ -3,6 +3,7 @@ package com.thoughtworks.dsl.keywords
 import com.thoughtworks.dsl.Dsl
 import com.thoughtworks.dsl.Dsl.Keyword
 import com.thoughtworks.dsl.keywords.Yield.From
+import com.thoughtworks.enableIf
 import com.thoughtworks.enableMembersIf
 
 import scala.collection._
@@ -68,6 +69,17 @@ private[keywords] object YieldScalaVersions {
 
     trait LowPriorityYield1 extends LowPriorityYield3 {
 
+      @enableIf(scala.util.Properties.versionNumberString.matches("""^2\.11\..*$"""))
+      implicit def seqViewYieldFromDsl[A, FromCollection <: Traversable[A], Coll1, Coll2](
+          implicit canBuildFrom: CanBuildFrom[SeqView[A, Coll1], A, SeqView[A, Coll2]])
+        : Dsl[From[FromCollection], SeqView[A, Coll1], Unit] =
+        new Dsl[From[FromCollection], SeqView[A, Coll1], Unit] {
+          def cpsApply(keyword: From[FromCollection], generateTail: Unit => SeqView[A, Coll1]): SeqView[A, Coll1] = {
+            (keyword.elements.toSeq.view ++: generateTail(()))(canBuildFrom).asInstanceOf[SeqView[A, Coll1]]
+          }
+        }
+
+      @enableIf(scala.util.Properties.versionNumberString.matches("""^2\.12\..*$"""))
       implicit def seqViewYieldFromDsl[A, FromCollection <: Traversable[A], Coll1, Coll2](
           implicit canBuildFrom: CanBuildFrom[SeqView[A, Coll1], A, SeqView[A, Coll2]])
         : Dsl[From[FromCollection], SeqView[A, Coll1], Unit] =
@@ -122,6 +134,20 @@ private[keywords] object YieldScalaVersions {
           }
         }
 
+      implicit def indexedSeqViewYieldFromDsl[A, FromCollection <: View.SomeIterableOps[A]]: Dsl[From[FromCollection], IndexedSeqView[A], Unit] =
+        new Dsl[From[FromCollection], IndexedSeqView[A], Unit] {
+          def cpsApply(keyword: From[FromCollection], generateTail: Unit => IndexedSeqView[A]): IndexedSeqView[A] = {
+            new IndexedSeqView.Concat(keyword.elements.toIndexedSeq, generateTail(()))
+          }
+        }
+
+      implicit def seqViewYieldFromDsl[A, FromCollection <: View.SomeIterableOps[A]]: Dsl[From[FromCollection], SeqView[A], Unit] =
+        new Dsl[From[FromCollection], SeqView[A], Unit] {
+          def cpsApply(keyword: From[FromCollection], generateTail: Unit => SeqView[A]): SeqView[A] = {
+            new SeqView.Concat(keyword.elements.toSeq, generateTail(()))
+          }
+        }
+
       implicit def seqViewYieldDsl[A, B >: A]: Dsl[Yield[A], SeqView[B], Unit] =
         new Dsl[Yield[A], SeqView[B], Unit] {
           def cpsApply(keyword: Yield[A], generateTail: Unit => SeqView[B]): SeqView[B] = {

diff --git a/keywords-Yield/src/test/scala/com/thoughtworks/dsl/keywords/YieldSpec.scala b/keywords-Yield/src/test/scala/com/thoughtworks/dsl/keywords/YieldSpec.scala
@@ -7,12 +7,13 @@ import scala.annotation.tailrec
 import scala.collection.{LinearSeq, SeqView}
 import scala.runtime.NonLocalReturnControl
 import org.scalatest.freespec.AnyFreeSpec
+import org.scalatest.Assertions
 import org.scalatest.matchers.should.Matchers
 
 /**
   * @author 杨博 (Yang Bo)
   */
-class YieldSpec extends AnyFreeSpec with Matchers {
+class YieldSpec extends AnyFreeSpec with Matchers with Assertions {
 
   {
     !Yield(1)
@@ -303,9 +304,28 @@ class YieldSpec extends AnyFreeSpec with Matchers {
 
   "view" - {
 
-    def shouldCompile = {
-      !Yield("naked")
-      Vector.empty[String].view
+    "indexed seq view" in {
+      def generator = {
+        !Yield("naked")
+        Vector.empty[String].view
+      }
+      assert(generator.toList == List("naked"))
+    }
+
+    "yield from indexed seq view" in {
+      def generator = {
+        !Yield(100, 101)
+        Vector.empty[Int].view
+      }
+      assert(generator.toList == List(100, 101))
+    }
+
+    "yield from seq view" in {
+      def generator = {
+        !Yield(100, 101)
+        Seq.empty[Int].view
+      }
+      assert(generator.toList == List(100, 101))
     }
 
     "local method" in {