Leaving a generator via an exception causes it to close

src/generator.js

Index: src/generator.js
diff --git a/src/generator.js b/src/generator.js
index b35744a094f29ef0acd8baf3180bdfb7234a9084..49a1ed266cf173c9fe78a08ba058ad0015006cb3 100644
--- a/src/generator.js
+++ b/src/generator.js
@@ -21,7 +21,12 @@ function GeneratorObjectNext(value) {
   }
 
   if (DEBUG_IS_ACTIVE) %DebugPrepareStepInIfStepping(this);
-  return %_GeneratorNext(this, value);
+  try {
+    return %_GeneratorNext(this, value);
+  } catch (e) {
+    %GeneratorClose(this);
+    throw e;
+  }
 }
 
 function GeneratorObjectThrow(exn) {
@@ -30,7 +35,12 @@ function GeneratorObjectThrow(exn) {
                         ['[Generator].prototype.throw', this]);
   }
 
-  return %_GeneratorThrow(this, exn);
+  try {
+    return %_GeneratorThrow(this, exn);
+  } catch (e) {

[rossberg, 2014/11/12 11:56:27]

Wait, won't this catch the very throw above?

[wingo, 2014/11/12 12:03:02]

It could, if the generator itself doesn't catch it.   But the generator could
catch it and return a value.

+    %GeneratorClose(this);
+    throw e;
+  }
 }
 
 function GeneratorObjectIterator() {