Replaces LongJump with LongJumpScope.

runtime/vm/longjump.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/longjump.h"
 
 #include "include/dart_api.h"
 
 #include "vm/dart_api_impl.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/os.h"
 #include "vm/simulator.h"
 
 namespace dart {
 
-jmp_buf* LongJump::Set() {
+jmp_buf* LongJumpScope::Set() {
+  ASSERT(top_ == NULL);
   top_ = Isolate::Current()->top_resource();
   return &environment_;
 }
 
 
-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();
   uword jumpbuf_addr = reinterpret_cast<uword>(this);
 #if defined(USING_SIMULATOR)
   uword top_exit_frame_info = isolate->simulator()->top_exit_frame_info();
 #else
   uword top_exit_frame_info = isolate->top_exit_frame_info();
 #endif
   return ((top_exit_frame_info == 0) || (jumpbuf_addr < top_exit_frame_info));
 }
 
 
-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());
 
   Isolate* isolate = Isolate::Current();
 
   // Remember the error in the sticky error of this isolate.
   isolate->object_store()->set_sticky_error(error);
 
   // Destruct all the active StackResource objects.
   StackResource* current_resource = isolate->top_resource();
   while (current_resource != top_) {
     current_resource->~StackResource();
     current_resource = isolate->top_resource();
   }
   longjmp(environment_, value);
   UNREACHABLE();
 }
 
 }  // namespace dart