From 7510ec80a4395fd2e9756a20c2ef95ff68e8daaa Mon Sep 17 00:00:00 2001
From: Mathias <mathias@decodified.com>
Date: Thu, 26 Feb 2015 15:47:39 +0100
Subject: [PATCH] !htp Refactor ExceptionHandler infrastructure for symmetry
 with RejectionHandler

---
 .../scala/akka/http/testkit/RouteTest.scala   |  6 +----
 .../akka/http/server/ExceptionHandler.scala   | 22 ++++++++++++++-----
 .../main/scala/akka/http/server/Route.scala   |  5 +----
 3 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/akka-http-testkit/src/main/scala/akka/http/testkit/RouteTest.scala b/akka-http-testkit/src/main/scala/akka/http/testkit/RouteTest.scala
index 3ec2b3f445..3e08df9201 100644
--- a/akka-http-testkit/src/main/scala/akka/http/testkit/RouteTest.scala
+++ b/akka-http-testkit/src/main/scala/akka/http/testkit/RouteTest.scala
@@ -126,11 +126,7 @@ trait RouteTest extends RequestBuilding with RouteTestResultComponent with Marsh
               securedConnection = defaultHostInfo.securedConnection,
               defaultHostHeader = defaultHostInfo.host)
           val ctx = new RequestContextImpl(effectiveRequest, setup.routingLog.requestLog(effectiveRequest), setup.settings)
-          val sealedExceptionHandler = {
-            import setup._
-            if (exceptionHandler.isDefault) exceptionHandler
-            else exceptionHandler orElse ExceptionHandler.default(settings)(setup.executionContext)
-          }
+          val sealedExceptionHandler = setup.exceptionHandler.seal(setup.settings)(setup.executionContext)
           val semiSealedRoute = // sealed for exceptions but not for rejections
             Directives.handleExceptions(sealedExceptionHandler) { route }
           val deferrableRouteResult = semiSealedRoute(ctx)
diff --git a/akka-http/src/main/scala/akka/http/server/ExceptionHandler.scala b/akka-http/src/main/scala/akka/http/server/ExceptionHandler.scala
index f34f367154..130cd9b8bc 100644
--- a/akka-http/src/main/scala/akka/http/server/ExceptionHandler.scala
+++ b/akka-http/src/main/scala/akka/http/server/ExceptionHandler.scala
@@ -10,23 +10,35 @@ import akka.http.model._
 import StatusCodes._
 
 trait ExceptionHandler extends ExceptionHandler.PF {
-  def isDefault: Boolean
+
+  /**
+   * Creates a new [[ExceptionHandler]] which uses the given one as fallback for this one.
+   */
+  def withFallback(that: ExceptionHandler): ExceptionHandler
+
+  /**
+   * "Seals" this handler by attaching a default handler as fallback if necessary.
+   */
+  def seal(settings: RoutingSettings)(implicit ec: ExecutionContext): ExceptionHandler
 }
 
 object ExceptionHandler {
   type PF = PartialFunction[Throwable, Route]
 
-  implicit def apply(pf: PF): ExceptionHandler = apply(default = false)(pf)
+  implicit def apply(pf: PF): ExceptionHandler = apply(knownToBeSealed = false)(pf)
 
-  private def apply(default: Boolean)(pf: PF): ExceptionHandler =
+  private def apply(knownToBeSealed: Boolean)(pf: PF): ExceptionHandler =
     new ExceptionHandler {
-      def isDefault: Boolean = default
       def isDefinedAt(error: Throwable) = pf.isDefinedAt(error)
       def apply(error: Throwable) = pf(error)
+      def withFallback(that: ExceptionHandler): ExceptionHandler =
+        if (!knownToBeSealed) ExceptionHandler(knownToBeSealed = false)(this orElse that) else this
+      def seal(settings: RoutingSettings)(implicit ec: ExecutionContext): ExceptionHandler =
+        if (!knownToBeSealed) ExceptionHandler(knownToBeSealed = true)(this orElse default(settings)) else this
     }
 
   def default(settings: RoutingSettings)(implicit ec: ExecutionContext): ExceptionHandler =
-    apply(default = true) {
+    apply(knownToBeSealed = true) {
       case IllegalRequestException(info, status) ⇒ ctx ⇒ {
         ctx.log.warning("Illegal request {}\n\t{}\n\tCompleting with '{}' response",
           ctx.request, info.formatPretty, status)
diff --git a/akka-http/src/main/scala/akka/http/server/Route.scala b/akka-http/src/main/scala/akka/http/server/Route.scala
index 2a155a6870..601a6fb08a 100644
--- a/akka-http/src/main/scala/akka/http/server/Route.scala
+++ b/akka-http/src/main/scala/akka/http/server/Route.scala
@@ -22,10 +22,7 @@ object Route {
   def seal(route: Route)(implicit setup: RoutingSetup): Route = {
     import directives.ExecutionDirectives._
     import setup._
-    val sealedExceptionHandler =
-      if (exceptionHandler.isDefault) exceptionHandler
-      else exceptionHandler orElse ExceptionHandler.default(settings)
-    handleExceptions(sealedExceptionHandler) {
+    handleExceptions(exceptionHandler.seal(settings)) {
       handleRejections(rejectionHandler.seal) {
         route
       }