Allow Using or scopeExit in plain functions

.gitignore

@@ -1,3 +1,4 @@
 target/
 local.sbt
 secret/
+.idea

keywords-Using/build.sbt

@@ -21,3 +21,4 @@ scalacOptions ++= {
 }
 
 libraryDependencies += "com.thoughtworks.dsl" %%% "keywords-await" % "1.3.1" % Test
+libraryDependencies += "com.thoughtworks.dsl" %%% "domains-task" % "1.3.1" % Test

keywords-Using/src/main/scala/com/thoughtworks/dsl/keywords/Using.scala

@@ -17,7 +17,23 @@ import scala.util.control.NonFatal
   */
 final case class Using[R <: AutoCloseable](open: () => R) extends AnyVal with Keyword[Using[R], R]
 
-object Using {
+trait LowPriorityUsing {
+
+  implicit def usingDsl[R <: AutoCloseable, Domain]: Dsl[Using[R], Domain, R] =
+    new Dsl[Using[R], Domain, R] {
+      def cpsApply(keyword: Using[R], handler: R => Domain): Domain = {
+        val r = keyword.open()
+        try {
+          handler(r)
+        } finally {
+          r.close()
+        }
+      }
+    }
+
+}
+
+object Using extends LowPriorityUsing {
 
   implicit def implicitUsing[R <: AutoCloseable](r: => R): Using[R] = Using[R](r _)
 

keywords-Using/src/test/scala/com/thoughtworks/dsl/keywords/UsingSpec.scala

@@ -0,0 +1,121 @@
+package com.thoughtworks.dsl.keywords
+
+import java.util.concurrent.LinkedBlockingQueue
+
+import org.scalatest.{FreeSpec, Matchers}
+import com.thoughtworks.dsl.domains.task.Task
+import scala.concurrent.duration._
+
+class UsingSpec extends FreeSpec with Matchers {
+
+  "scopeExit" - {
+    import Using.scopeExit
+
+    "execute sequence: function" in {
+      val queue = new LinkedBlockingQueue[Int]()
+
+      def run() = {
+        !scopeExit(() => queue.offer(1))
+        queue.offer(2)
+      }
+
+      run()
+
+      queue.poll() should be(2)
+      queue.poll() should be(1)
+    }
+
+    "execute sequence: function contains call-by-name function call" in {
+      val queue = new LinkedBlockingQueue[Int]()
+
+      def runOp(op: => Unit): Unit = op
+
+      def run() = {
+        !scopeExit(() => queue.offer(1))
+        runOp {
+          !scopeExit(() => queue.offer(3))
+        }
+        queue.offer(2)
+      }
+
+      run()
+
+      queue.poll() should be(3)
+      queue.poll() should be(2)
+      queue.poll() should be(1)
+    }
+
+    "execute sequence: function contains call of function accepts function literal execute sequence" in {
+      val queue = new LinkedBlockingQueue[Int]()
+
+      def runOp(op: () => Unit): Unit = op()
+
+      def run() = {
+        !scopeExit(() => queue.offer(1))
+        runOp(() => !scopeExit(() => queue.offer(3)))
+        queue.offer(2)
+      }
+
+      run()
+
+      queue.poll() should be(3)
+      queue.poll() should be(2)
+      queue.poll() should be(1)
+    }
+
+    "execute sequence: task" in {
+      val queue = new LinkedBlockingQueue[Int]()
+
+      def run() = Task {
+        !scopeExit(() => queue.offer(1))
+        queue.offer(2)
+      }
+
+      Task.blockingAwait(run(), 1.minute)
+
+      queue.poll() should be(2)
+      queue.poll() should be(1)
+    }
+
+
+    "execute sequence: task contains call-by-name function call" in {
+      val queue = new LinkedBlockingQueue[Int]()
+
+      def runTask(op: => Task[Unit]): Unit = Task.blockingAwait(op, 1.minute)
+
+      def run() = Task {
+        !scopeExit(() => queue.offer(1))
+        runTask {
+          Task(!scopeExit(() => queue.offer(3)))
+        }
+        queue.offer(2)
+      }
+
+      Task.blockingAwait(run(), 1.minute)
+
+      queue.poll() should be(3)
+      queue.poll() should be(2)
+      queue.poll() should be(1)
+    }
+
+    "execute sequence: task contains call of function accepts function literal execute sequence" in {
+      val queue = new LinkedBlockingQueue[Int]()
+
+      def runOp(op: () => Task[Unit]): Unit = Task.blockingAwait(op(), 1.minute)
+
+      def run() = {
+        !scopeExit(() => queue.offer(1))
+        runOp(() => Task(!scopeExit(() => queue.offer(3))))
+        queue.offer(2)
+      }
+
+      run()
+
+      queue.poll() should be(3)
+      queue.poll() should be(2)
+      queue.poll() should be(1)
+    }
+
+  }
+
+}