added support for continuations in try/catch bl...

added support for continuations in try/catch blocks. review by
community.

2 files changed, 71 insertions, 16 deletions

diff --git a/src/continuations/library/scala/util/continuations/ControlContext.scala b/src/continuations/library/scala/util/continuations/ControlContext.scala
index 709d2d2b02..9ed83a7e71 100644
--- a/src/continuations/library/scala/util/continuations/ControlContext.scala
+++ b/src/continuations/library/scala/util/continuations/ControlContext.scala
@@ -14,21 +14,39 @@ private class cpsMinus extends Annotation // implementation detail
 
 
 
-@serializable final class ControlContext[+A,-B,+C](val fun: (A => B) => C, val x: A) {
+@serializable final class ControlContext[+A,-B,+C](val fun: (A => B, Throwable => B) => C, val x: A) {
 
-  final def map[A1](f: (A => A1)): ControlContext[A1,B,C] = {
-    if (fun eq null)
-      new ControlContext(null, f(x))
-    else
+  /*
+    final def map[A1](f: A => A1): ControlContext[A1,B,C] = {
       new ControlContext((k:(A1 => B)) => fun((x:A) => k(f(x))), null.asInstanceOf[A1])
-  }
+    }
 
-  /*
     final def flatMap[A1,B1<:B](f: (A => ControlContext[A1,B1,B])): ControlContext[A1,B1,C] = {
       new ControlContext((k:(A1 => B1)) => fun((x:A) => f(x).fun(k)))
     }
   */
 
+
+  final def map[A1](f: A => A1): ControlContext[A1,B,C] = {
+    if (fun eq null)
+      new ControlContext(null, f(x))
+    else
+      new ControlContext({ (k: A1 => B, thr: Throwable => B) =>
+        fun( { (x:A) =>
+          var done = false
+          try {
+            val res = f(x)
+            done = true
+            k(res)
+          } catch {
+            case ex if !done =>
+              thr(ex)
+          }
+        }, thr)
+      }, null.asInstanceOf[A1])
+  }
+
+
   // it would be nice if @inline would turn the trivial path into a tail call.
   // unfortunately it doesn't, so we do it ourselves in SelectiveCPSTransform
 
@@ -36,25 +54,62 @@ private class cpsMinus extends Annotation // implementation detail
     if (fun eq null)
       f(x).asInstanceOf[ControlContext[A1,B1,C]]
     else
-      new ControlContext({ k:(A1 => B1) =>
-        fun { (x:A) =>
-          val ctxR = f(x)
-          val res: C1 = ctxR.foreach(k)
-          res
-        }
+      new ControlContext({ (k: A1 => B1, thr: Throwable => B1) =>
+        fun( { (x:A) =>
+          var done = false
+          try {
+            val ctxR = f(x)
+            done = true
+            val res: C1 = ctxR.foreachFull(k, thr) // => B1
+            res
+          } catch {
+            case ex if !done =>
+              thr(ex).asInstanceOf[B] // => B NOTE: in general this is unsafe!
+          }                           // However, the plugin will not generate offending code
+        }, thr.asInstanceOf[Throwable=>B]) // => B
       }, null.asInstanceOf[A1])
   }
 
-  final def foreach(f: (A => B)) = {
+  final def foreach(f: A => B) = foreachFull(f, throw _)
+
+  def foreachFull(f: A => B, g: Throwable => B): C = {
     if (fun eq null)
       f(x).asInstanceOf[C]
     else
-      fun(f)
+      fun(f, g)
   }
 
+
   final def isTrivial = fun eq null
   final def getTrivialValue = x.asInstanceOf[A]
 
   // need filter or other functions?
 
+  final def flatCat[A1>:A,B1<:B,C1>:C<:B1](pf: PartialFunction[Throwable, ControlContext[A1,B1,C1]]): ControlContext[A1,B1,C1] = {
+    if (fun eq null)
+      this
+    else {
+      val fun1 = (ret1: A1 => B1, thr1: Throwable => B1) => {
+        val thr: Throwable => B1 = { t: Throwable =>
+          var captureExceptions = true
+          try {
+            if (pf.isDefinedAt(t)) {
+              val cc1 = pf(t)
+              captureExceptions = false
+              cc1.foreachFull(ret1, thr1) // Throw => B
+            } else {
+              captureExceptions = false
+              thr1(t) // Throw => B1
+            }
+          } catch {
+            case t1 if captureExceptions => thr1(t1) // => E2
+          }
+        }
+        foreachFull(ret1, thr)// fun(ret1, thr)  // => B
+      }
+      new ControlContext(fun1, null.asInstanceOf[A1])
+    }
+  }
+
+  // TODO: finally
 }
diff --git a/src/continuations/library/scala/util/continuations/package.scala b/src/continuations/library/scala/util/continuations/package.scala
index 0d924565c1..1fa89da2b4 100644
--- a/src/continuations/library/scala/util/continuations/package.scala
+++ b/src/continuations/library/scala/util/continuations/package.scala
@@ -55,7 +55,7 @@ package object continuations {
   }
 
   def shiftR[A,B,C](fun: (A => B) => C): ControlContext[A,B,C] = {
-    new ControlContext(fun, null.asInstanceOf[A])
+    new ControlContext((f:A=>B,g:Throwable=>B) => fun(f), null.asInstanceOf[A])
   }
 
   def reifyR[A,B,C](ctx: => ControlContext[A,B,C]): ControlContext[A,B,C] = {