Replaces LongJump with LongJumpScope.

runtime/vm/longjump.cc

Index: runtime/vm/longjump.cc
===================================================================
--- runtime/vm/longjump.cc	(revision 31413)
+++ runtime/vm/longjump.cc	(working copy)
@@ -15,13 +15,13 @@
 
 namespace dart {
 
-jmp_buf* LongJump::Set() {
+jmp_buf* LongJumpScope::Set() {
   top_ = Isolate::Current()->top_resource();
   return &environment_;

[siva, 2014/01/03 21:18:35]

We need an assertion here to ensure that Set is called only once within a
LongJumpScope.

The code below for example is illegal now:

{
  LongJumpScope ls;
  ...
  if (setjmp(*ls.Set()) == 0) {
    ...
  } else {
    ...
  }
  ...
  ...
  if (setjmp(*ls.Set() == 0) {
    ...
  } else {
    ...
  }
}

It was ok before because of the manual reset.

[zra, 2014/01/03 21:52:59]

Done.

 }
 
 
-bool LongJump::IsSafeToJump() {
+bool LongJumpScope::IsSafeToJump() {
   // We do not want to jump past Dart frames.  Note that this code
   // assumes the stack grows from high to low.
   Isolate* isolate = Isolate::Current();
@@ -35,8 +35,9 @@
 }
 
 
-void LongJump::Jump(int value, const Error& error) {
-  // A zero is the default return value from setting up a LongJump using Set.
+void LongJumpScope::Jump(int value, const Error& error) {
+  // A zero is the default return value from setting up a LongJumpScope
+  // using Set.
   ASSERT(value != 0);
   ASSERT(IsSafeToJump());