Add TraverseFilter instance for Queue.

typelevel · Oct 9, 2019 · a7f0097 · a7f0097
1 parent dc44c3b
commit a7f0097
Show file tree

Hide file tree

Showing 7 changed files with 40 additions and 3 deletions.
diff --git a/core/src/main/scala-2.12/cats/instances/all.scala b/core/src/main/scala-2.12/cats/instances/all.scala
@@ -10,6 +10,7 @@ abstract class AllInstancesBinCompat
     with AllInstancesBinCompat4
     with AllInstancesBinCompat5
     with AllInstancesBinCompat6
+    with AllInstancesBinCompat7
 
 trait AllInstances
     extends AnyValInstances
@@ -62,3 +63,5 @@ trait AllInstancesBinCompat4 extends SortedMapInstancesBinCompat1 with MapInstan
 trait AllInstancesBinCompat5 extends SortedSetInstancesBinCompat0
 
 trait AllInstancesBinCompat6 extends SortedSetInstancesBinCompat1 with SortedMapInstancesBinCompat2
+
+trait AllInstancesBinCompat7 extends QueueInstancesBinCompat0
diff --git a/core/src/main/scala-2.12/cats/instances/package.scala b/core/src/main/scala-2.12/cats/instances/package.scala
@@ -28,7 +28,7 @@ package object instances {
   object parallel extends ParallelInstances
   object partialOrder extends PartialOrderInstances
   object partialOrdering extends PartialOrderingInstances
-  object queue extends QueueInstances
+  object queue extends QueueInstances with QueueInstancesBinCompat0
   object set extends SetInstances
   object short extends ShortInstances
   object sortedMap

diff --git a/core/src/main/scala-2.13+/cats/instances/all.scala b/core/src/main/scala-2.13+/cats/instances/all.scala
@@ -10,6 +10,7 @@ abstract class AllInstancesBinCompat
     with AllInstancesBinCompat4
     with AllInstancesBinCompat5
     with AllInstancesBinCompat6
+    with AllInstancesBinCompat7
 
 trait AllInstances
     extends AnyValInstances
@@ -63,3 +64,5 @@ trait AllInstancesBinCompat4 extends SortedMapInstancesBinCompat1 with MapInstan
 trait AllInstancesBinCompat5 extends SortedSetInstancesBinCompat0
 
 trait AllInstancesBinCompat6 extends SortedSetInstancesBinCompat1 with SortedMapInstancesBinCompat2
+
+trait AllInstancesBinCompat7 extends QueueInstancesBinCompat0
diff --git a/core/src/main/scala-2.13+/cats/instances/package.scala b/core/src/main/scala-2.13+/cats/instances/package.scala
@@ -28,7 +28,7 @@ package object instances {
   object parallel extends ParallelInstances
   object partialOrder extends PartialOrderInstances
   object partialOrdering extends PartialOrderingInstances
-  object queue extends QueueInstances
+  object queue extends QueueInstances with QueueInstancesBinCompat0
   object set extends SetInstances
   object short extends ShortInstances
   object sortedMap

diff --git a/core/src/main/scala/cats/instances/queue.scala b/core/src/main/scala/cats/instances/queue.scala
@@ -153,3 +153,30 @@ trait QueueInstances extends cats.kernel.instances.QueueInstances {
         fa.iterator.map(_.show).mkString("Queue(", ", ", ")")
     }
 }
+
+private[instances] trait QueueInstancesBinCompat0 {
+  implicit val catsStdTraverseFilterForQueue: TraverseFilter[Queue] = new TraverseFilter[Queue] {
+    val traverse: Traverse[Queue] = cats.instances.queue.catsStdInstancesForQueue
+
+    override def mapFilter[A, B](fa: Queue[A])(f: (A) => Option[B]): Queue[B] =
+      fa.collect(Function.unlift(f))
+
+    override def filter[A](fa: Queue[A])(f: (A) => Boolean): Queue[A] = fa.filter(f)
+
+    override def collect[A, B](fa: Queue[A])(f: PartialFunction[A, B]): Queue[B] = fa.collect(f)
+
+    override def flattenOption[A](fa: Queue[Option[A]]): Queue[A] = fa.flatten
+
+    def traverseFilter[G[_], A, B](fa: Queue[A])(f: (A) => G[Option[B]])(implicit G: Applicative[G]): G[Queue[B]] =
+      fa.foldRight(Eval.now(G.pure(Queue.empty[B])))(
+          (x, xse) => G.map2Eval(f(x), xse)((i, o) => i.fold(o)(_ +: o))
+        )
+        .value
+
+    override def filterA[G[_], A](fa: Queue[A])(f: (A) => G[Boolean])(implicit G: Applicative[G]): G[Queue[A]] =
+      fa.foldRight(Eval.now(G.pure(Queue.empty[A])))(
+          (x, xse) => G.map2Eval(f(x), xse)((b, vec) => if (b) x +: vec else vec)
+        )
+        .value
+  }
+}
diff --git a/tests/src/test/scala/cats/tests/CatsSuite.scala b/tests/src/test/scala/cats/tests/CatsSuite.scala
@@ -45,6 +45,7 @@ trait CatsSuite
     with AllInstancesBinCompat4
     with AllInstancesBinCompat5
     with AllInstancesBinCompat6
+    with AllInstancesBinCompat7
     with AllSyntax
     with AllSyntaxBinCompat0
     with AllSyntaxBinCompat1

diff --git a/tests/src/test/scala/cats/tests/QueueSuite.scala b/tests/src/test/scala/cats/tests/QueueSuite.scala
@@ -2,13 +2,13 @@ package cats
 package tests
 
 import scala.collection.immutable.Queue
-
 import cats.laws.discipline.{
   AlternativeTests,
   CoflatMapTests,
   MonadTests,
   SemigroupalTests,
   SerializableTests,
+  TraverseFilterTests,
   TraverseTests
 }
 
@@ -28,6 +28,9 @@ class QueueSuite extends CatsSuite {
   checkAll("Queue[Int] with Option", TraverseTests[Queue].traverse[Int, Int, Int, Set[Int], Option, Option])
   checkAll("Traverse[Queue]", SerializableTests.serializable(Traverse[Queue]))
 
+  checkAll("Queue[Int]", TraverseFilterTests[Queue].traverseFilter[Int, Int, Int])
+  checkAll("TraverseFilter[Queue]", SerializableTests.serializable(TraverseFilter[Queue]))
+
   test("show") {
     Queue(1, 2, 3).show should ===("Queue(1, 2, 3)")
     Queue.empty[Int].show should ===("Queue()")