Merge pull request #2 from ThoughtWorksInc/exception-handling

Support new exception handling in Dsl.scala 1.4
ThoughtWorksInc · Jun 23, 2019 · 1864cb7 · 1864cb7
2 parents 8b7680f + b5d7e0e
commit 1864cb7
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Showing 2 changed files with 56 additions and 9 deletions.
diff --git a/domains-cats/build.sbt b/domains-cats/build.sbt
@@ -6,19 +6,19 @@ libraryDependencies += "org.typelevel" %%% "cats-core" % "2.0.0-M4"
 
 libraryDependencies += "org.scalatest" %%% "scalatest" % "3.0.8" % Test
 
-libraryDependencies += "com.thoughtworks.dsl" %%% "keywords-catch" % "1.3.2"
+libraryDependencies += "com.thoughtworks.dsl" %%% "keywords-catch" % "1.4.0"
 
-libraryDependencies += "com.thoughtworks.dsl" %%% "keywords-monadic" % "1.3.2"
+libraryDependencies += "com.thoughtworks.dsl" %%% "keywords-monadic" % "1.4.0"
 
-libraryDependencies += "com.thoughtworks.dsl" %%% "keywords-return" % "1.3.2"
+libraryDependencies += "com.thoughtworks.dsl" %%% "keywords-return" % "1.4.0"
 
-libraryDependencies += "com.thoughtworks.dsl" %%% "keywords-shift" % "1.3.2" % Optional
+libraryDependencies += "com.thoughtworks.dsl" %%% "keywords-shift" % "1.4.0" % Optional
 
-libraryDependencies += "com.thoughtworks.dsl" %%% "keywords-yield" % "1.3.2" % Optional
+libraryDependencies += "com.thoughtworks.dsl" %%% "keywords-yield" % "1.4.0" % Optional
 
-addCompilerPlugin("com.thoughtworks.dsl" %% "compilerplugins-bangnotation" % "1.3.2")
+addCompilerPlugin("com.thoughtworks.dsl" %% "compilerplugins-bangnotation" % "1.4.0")
 
-addCompilerPlugin("com.thoughtworks.dsl" %% "compilerplugins-reseteverywhere" % "1.3.2")
+addCompilerPlugin("com.thoughtworks.dsl" %% "compilerplugins-reseteverywhere" % "1.4.0")
 
 scalacOptions ++= {
   import Ordering.Implicits._

diff --git a/domains-cats/src/main/scala/com/thoughtworks/dsl/domains/cats.scala b/domains-cats/src/main/scala/com/thoughtworks/dsl/domains/cats.scala
@@ -3,7 +3,7 @@ package domains
 
 import _root_.cats.{Applicative, FlatMap}
 import com.thoughtworks.dsl.Dsl
-import com.thoughtworks.dsl.Dsl.!!
+import com.thoughtworks.dsl.Dsl.{!!, TryCatch, TryFinally}
 import _root_.cats.MonadError
 import com.thoughtworks.Extractor._
 import com.thoughtworks.dsl.keywords.Catch.CatchDsl
@@ -12,6 +12,7 @@ import com.thoughtworks.dsl.keywords.{Monadic, Return}
 import scala.language.higherKinds
 import scala.language.implicitConversions
 import scala.util.control.Exception.Catcher
+import scala.util.control.NonFatal
 
 /** Contains interpreters to enable [[Dsl.Keyword#unary_$bang !-notation]]
   * for [[keywords.Monadic]] and other keywords
@@ -112,8 +113,54 @@ object cats {
     (keyword: Return[A], handler: Nothing => F[B]) =>
       applicative.pure(restReturnDsl.cpsApply(keyword, identity))
   }
+  @inline private def catchNativeException[F[_], A](continuation: F[A] !! A)(
+      implicit monadThrowable: MonadThrowable[F]): F[A] = {
+    try {
+      continuation(monadThrowable.pure(_))
+    } catch {
+      case NonFatal(e) =>
+        monadThrowable.raiseError(e)
+    }
+  }
+
+  implicit def catsTryFinally[F[_], A, B](
+      implicit monadError: MonadThrowable[F]): TryFinally[A, F[B], F[A], F[Unit]] = {
+    (block: F[A] !! A, finalizer: F[Unit] !! Unit, outerSuccessHandler: A => F[B]) =>
+      @inline
+      def injectFinalizer[A](f: Unit => F[A]): F[A] = {
+        monadError.flatMap(catchNativeException(finalizer))(f)
+      }
+
+      monadError.flatMap(monadError.handleErrorWith(catchNativeException(block)) { e: Throwable =>
+        injectFinalizer { _: Unit =>
+          monadError.raiseError(e)
+        }
+      }) { a =>
+        injectFinalizer { _: Unit =>
+          outerSuccessHandler(a)
+        }
+      }
+  }
+
+  implicit def catsTryCatch[F[_], A, B](implicit monadError: MonadThrowable[F]): TryCatch[A, F[B], F[A]] = {
+    (block: F[A] !! A, catcher: Catcher[F[A] !! A], outerSuccessHandler: A => F[B]) =>
+      def errorHandler(e: Throwable): F[A] = {
+        (try {
+          catcher.lift(e)
+        } catch {
+          case NonFatal(extractorException) =>
+            return monadError.raiseError(extractorException)
+        }) match {
+          case None =>
+            monadError.raiseError(e)
+          case Some(recovered) =>
+            catchNativeException(recovered)
+        }
+      }
+      monadError.flatMap(monadError.handleErrorWith(catchNativeException(block))(errorHandler))(outerSuccessHandler)
+  }
 
-  implicit def catsCatchDsl[F[_], A, B](implicit monadError: MonadThrowable[F]): CatchDsl[F[A], F[B], A] = {
+  private[dsl] def catsCatchDsl[F[_], A, B](implicit monadError: MonadThrowable[F]): CatchDsl[F[A], F[B], A] = {
     (block: F[A] !! A, catcher: Catcher[F[A] !! A], handler: A => F[B]) =>
       val fa = monadError.flatMap(monadError.pure(block))(_(monadError.pure))
       val protectedFa = monadError.handleErrorWith(fa) {