Implement Fast Accessor Builder

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index c5479c518ed374fbd6c58586cef6481b3182eeb0..8c1b769add5f1cdb2b6ff37e0fbe01eac566ed28 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -136,6 +136,10 @@ class CallHandlerHelper;
 class EscapableHandleScope;
 template<typename T> class ReturnValue;
 
+namespace experimental {
+class FastAccessorBuilder;
+}  // namespace experimental
+
 namespace internal {
 class Arguments;
 class Heap;
@@ -4416,6 +4420,16 @@ class V8_EXPORT FunctionTemplate : public Template {
    * the callback cannot be null.
    */
   static Local<FunctionTemplate> NewWithFastHandler(
+      Isolate* isolate, FunctionCallback callback,
+      experimental::FastAccessorBuilder* fast_handler = nullptr,
+      Local<Value> data = Local<Value>(),
+      Local<Signature> signature = Local<Signature>(), int length = 0);
+
+  /**
+   * Creates a function template with a fast handler. If a fast handler is set,
+   * the callback cannot be null.
+   */
+  static Local<FunctionTemplate> NewWithFastHandler(
       Isolate* isolate, FunctionCallback callback, Local<Value> fast_handler,
       Local<Value> data = Local<Value>(),
       Local<Signature> signature = Local<Signature>(), int length = 0);
@@ -4430,9 +4444,9 @@ class V8_EXPORT FunctionTemplate : public Template {
    * callback is called whenever the function created from this
    * FunctionTemplate is called.
    */
-  void SetCallHandler(FunctionCallback callback,
-                      Local<Value> data = Local<Value>(),
-                      Local<Value> fast_handler = Local<Value>());
+  void SetCallHandler(
+      FunctionCallback callback, Local<Value> data = Local<Value>(),
+      experimental::FastAccessorBuilder* fast_handler = nullptr);
 
   /** Set the predefined length property for the FunctionTemplate. */
   void SetLength(int length);
@@ -6965,6 +6979,43 @@ class V8_EXPORT Locker {
 };
 
 
+namespace experimental {
+
+class V8_EXPORT FastAccessorBuilder {
+ public:
+  struct ValueId {
+    size_t value_id;
+  };
+  struct LabelId {
+    size_t label_id;
+  };
+
+  ~FastAccessorBuilder();
+  static FastAccessorBuilder* New(Isolate* isolate);
+
+  ValueId IntegerConstant(int int_constant);
+  ValueId GetCallTarget();
+  ValueId GetParameter(size_t parameter_no);
+  ValueId GetInternalField(ValueId value_id, int field_no);
+  ValueId LoadValue(ValueId value_id, int offset);
+  ValueId LoadObject(ValueId value_id, int offset);
+  void ReturnValue(ValueId value_id);
+  void CheckFlagSetOrReturnNull(ValueId value_id, int mask);
+  void CheckNotNullOrReturnNull(ValueId value_id);
+  ValueId SetLabel();
+  void CheckNotNullOrJump(ValueId value_id, ValueId label_id);
+
+ private:
+  FastAccessorBuilder();
+  FastAccessorBuilder(const FastAccessorBuilder&) = delete;
+  void operator=(const FastAccessorBuilder&) = delete;
+
+  void* impl_;
+};
+
+}  // namespace experimental
+
+
 // --- Implementation ---