Introduce MaybeHandle to police exception checking in handlified code.

src/isolate.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 116 matching lines @@
 
 #define RETURN_HANDLE_IF_SCHEDULED_EXCEPTION(isolate, T)  \
   do {                                                    \
     Isolate* __isolate__ = (isolate);                     \
     if (__isolate__->has_scheduled_exception()) {         \
       __isolate__->PromoteScheduledException();           \
       return Handle<T>::null();                           \
     }                                                     \
   } while (false)
 
-#define RETURN_IF_EMPTY_HANDLE_VALUE(isolate, call, value) \
-  do {                                                     \
-    if ((call).is_null()) {                                \
-      ASSERT((isolate)->has_pending_exception());          \
-      return (value);                                      \
-    }                                                      \
+#define RETURN_IF_EMPTY_HANDLE_VALUE(isolate, call, value)  \
+  do {                                                      \
+    if ((call).is_null()) {                                 \
+      ASSERT((isolate)->has_pending_exception());           \
+      return (value);                                       \
+    }                                                       \
   } while (false)
 
 #define CHECK_NOT_EMPTY_HANDLE(isolate, call)     \
   do {                                            \
     ASSERT(!(isolate)->has_pending_exception());  \
     CHECK(!(call).is_null());                     \
   } while (false)
 
-#define RETURN_IF_EMPTY_HANDLE(isolate, call)                       \
+#define RETURN_IF_EMPTY_HANDLE(isolate, call)  \
   RETURN_IF_EMPTY_HANDLE_VALUE(isolate, call, Failure::Exception())
 
+
+// Macros for MaybeHandle.
+
+#define RETURN_EXCEPTION_IF_SCHEDULED_EXCEPTION(isolate, T)  \
+  do {                                                       \
+    Isolate* __isolate__ = (isolate);                        \
+    if (__isolate__->has_scheduled_exception()) {            \
+      __isolate__->PromoteScheduledException();              \
+      return MaybeHandle<T>();                               \
+    }                                                        \
+  } while (false)
+
+#define ASSIGN_RETURN_ON_EXCEPTION_VALUE(isolate, dst, call, value)  \
+  do {                                                               \
+    if (!(call).ToHandle(&dst)) {                                    \
+      ASSERT((isolate)->has_pending_exception());                    \
+      return value;                                                  \
+    }                                                                \
+  } while (false)
+
+#define ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, dst, call)  \
+  ASSIGN_RETURN_ON_EXCEPTION_VALUE(isolate, dst, call, Failure::Exception())
+
+#define ASSIGN_RETURN_ON_EXCEPTION(isolate, dst, call, T)  \
+  ASSIGN_RETURN_ON_EXCEPTION_VALUE(isolate, dst, call, MaybeHandle<T>())
+
+#define RETURN_ON_EXCEPTION_VALUE(isolate, dst, call, value)  \
+  do {                                                             \
+    if (call.is_null()) {                                          \
+      ASSERT((isolate)->has_pending_exception());                  \
+      return value;                                                \
+    }                                                              \
+  } while (false)
+
+#define RETURN_FAILURE_ON_EXCEPTION(isolate, call)  \
+  RETURN_ON_EXCEPTION_VALUE(isolate, dst, call, Failure::Exception())
+
+#define RETURN_ON_EXCEPTION(isolate, call, T)  \
+  RETURN_ON_EXCEPTION_VALUE(                   \
+      isolate, dst, call, MaybeHandle<T>::Exception())
+
+
 #define FOR_EACH_ISOLATE_ADDRESS_NAME(C)                \
   C(Handler, handler)                                   \
   C(CEntryFP, c_entry_fp)                               \
   C(Context, context)                                   \
   C(PendingException, pending_exception)                \
   C(ExternalCaughtException, external_caught_exception) \
   C(JSEntrySP, js_entry_sp)
 
 
 // Platform-independent, reliable thread identifier.
@@ skipping 596 matching lines @@
   bool MayIndexedAccess(JSObject* receiver,
                         uint32_t index,
                         v8::AccessType type);
 
   void SetFailedAccessCheckCallback(v8::FailedAccessCheckCallback callback);
   void ReportFailedAccessCheck(JSObject* receiver, v8::AccessType type);
 
   // Exception throwing support. The caller should use the result
   // of Throw() as its return value.
   Failure* Throw(Object* exception, MessageLocation* location = NULL);
+
+  template <typename T>
+  MUST_USE_RESULT MaybeHandle<T> Throw(Handle<Object> exception,
+                                       MessageLocation* location = NULL) {
+    Throw(*exception, location);
+    return MaybeHandle<T>();
+  }
+
   // Re-throw an exception.  This involves no error reporting since
   // error reporting was handled when the exception was thrown
   // originally.
   Failure* ReThrow(MaybeObject* exception);
   void ScheduleThrow(Object* exception);
   // Re-set pending message, script and positions reported to the TryCatch
   // back to the TLS for re-use when rethrowing.
   void RestorePendingMessageFromTryCatch(v8::TryCatch* handler);
   void ReportPendingMessages();
   // Return pending location if any or unfilled structure.
@@ skipping 752 matching lines @@
   }
 
   EmbeddedVector<char, 128> filename_;
   FILE* file_;
   int scope_depth_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ISOLATE_H_