Add a second kind of HandleScope that ties the lifetime of Handles created in its scope to the life…

src/handles.h

Index: src/handles.h
diff --git a/src/handles.h b/src/handles.h
index 960696b5fb81f705f2128b5586fef44ca0c8e7fb..a369646600556d94a27c2870d1463cbc67a66fe0 100644
--- a/src/handles.h
+++ b/src/handles.h
@@ -95,6 +95,9 @@ class Handle {
 };
 
 
+class HandleScopeImplementer;
+
+
 // A stack-allocated class that governs a number of local handles.
 // After a handle scope has been created, all local handles will be
 // allocated within that handle scope until either the handle scope is
@@ -157,10 +160,54 @@ class HandleScope {
   static void ZapRange(internal::Object** start, internal::Object** end);
 
   friend class v8::HandleScope;
+  friend class v8::internal::HandleScopeImplementer;
   friend class v8::ImplementationUtilities;
 };
 
 
+class DeferredHandles;
+
+
+class DeferredHandleScope {
+ public:
+  explicit DeferredHandleScope(Isolate* isolate);
+  // The DeferredHandles object returned stores the Handles created
+  // since the creation of this DeferredHandleScope.  The Handles are
+  // alive till as long as the DeferredHandles object is alive.

[Erik Corry, 2012/06/27 10:28:15]

till as long as -> as long as

[sanjoy, 2012/06/27 11:17:09]

Fixed.

+  DeferredHandles* Detach();
+  ~DeferredHandleScope();
+
+ private:
+  Object** prev_limit_;
+  Object** prev_next_;
+  HandleScopeImplementer* impl_;
+
+#ifdef DEBUG
+  bool handles_detached_;
+  int prev_level_;
+#endif
+
+  friend class HandleScopeImplementer;
+};
+
+
+class CompilationInfo;

[Erik Corry, 2012/06/27 10:28:15]

This declaration and the CompilationHandleScope are uses of handles and not part
of the handles interface, so they should go somewhere else, like perhaps
hydrogen.h

[sanjoy, 2012/06/27 11:17:09]

Moved to compiler.h.

+
+
+// A wrapper around a CompilationInfo that Detaches the Handles from

[Erik Corry, 2012/06/27 10:28:15]

Detaches -> detaches

[sanjoy, 2012/06/27 11:17:09]

Fixed.

+// the underlying DeferredHandleScope and stores them in info_ on
+// destruction.
+class CompilationHandleScope BASE_EMBEDDED {
+ public:
+  explicit CompilationHandleScope(CompilationInfo* info);
+  ~CompilationHandleScope();
+
+ private:
+  DeferredHandleScope deferred_;
+  CompilationInfo* info_;
+};
+
+
 // ----------------------------------------------------------------------------
 // Handle operations.
 // They might invoke garbage collection. The result is an handle to