Calling a generator function returns a generator object

src/objects.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 44 matching lines @@
 //     - HeapObject   (superclass for everything allocated in the heap)
 //       - JSReceiver  (suitable for property access)
 //         - JSObject
 //           - JSArray
 //           - JSArrayBuffer
 //           - JSSet
 //           - JSMap
 //           - JSWeakMap
 //           - JSRegExp
 //           - JSFunction
+//           - JSGeneratorIterator

[Michael Starzinger, 2013/04/08 13:14:05]

As discussed offline, the name "JSGeneratorIterator" is confusing. We should
change it to either "JSGeneratorObject" or "JSGeneratorInstance".

Just for the record, I personally would still name it just "JSGenerator" but I
see that we might want to reserve that name if at some point we need an instance
type for generator functions, so you and Andreas convinced me of the above two
alternatives.

 //           - JSModule
 //           - GlobalObject
 //             - JSGlobalObject
 //             - JSBuiltinsObject
 //           - JSGlobalProxy
 //           - JSValue
 //             - JSDate
 //           - JSMessageObject
 //         - JSProxy
 //           - JSFunctionProxy
@@ skipping 313 matching lines @@
   V(FIXED_ARRAY_TYPE)                                                          \
   V(FIXED_DOUBLE_ARRAY_TYPE)                                                   \
   V(SHARED_FUNCTION_INFO_TYPE)                                                 \
                                                                                \
   V(JS_MESSAGE_OBJECT_TYPE)                                                    \
                                                                                \
   V(JS_VALUE_TYPE)                                                             \
   V(JS_DATE_TYPE)                                                              \
   V(JS_OBJECT_TYPE)                                                            \
   V(JS_CONTEXT_EXTENSION_OBJECT_TYPE)                                          \
+  V(JS_GENERATOR_ITERATOR_TYPE)                                                \
   V(JS_MODULE_TYPE)                                                            \
   V(JS_GLOBAL_OBJECT_TYPE)                                                     \
   V(JS_BUILTINS_OBJECT_TYPE)                                                   \
   V(JS_GLOBAL_PROXY_TYPE)                                                      \
   V(JS_ARRAY_TYPE)                                                             \
   V(JS_ARRAY_BUFFER_TYPE)                                                      \
   V(JS_PROXY_TYPE)                                                             \
   V(JS_WEAK_MAP_TYPE)                                                          \
   V(JS_REGEXP_TYPE)                                                            \
                                                                                \
@@ skipping 311 matching lines @@
   // the two forms of function. This organization enables using the same
   // compares for checking the JS_RECEIVER/SPEC_OBJECT range and the
   // NONCALLABLE_JS_OBJECT range.
   JS_FUNCTION_PROXY_TYPE,  // FIRST_JS_RECEIVER_TYPE, FIRST_JS_PROXY_TYPE
   JS_PROXY_TYPE,  // LAST_JS_PROXY_TYPE
 
   JS_VALUE_TYPE,  // FIRST_JS_OBJECT_TYPE
   JS_DATE_TYPE,
   JS_OBJECT_TYPE,
   JS_CONTEXT_EXTENSION_OBJECT_TYPE,
+  JS_GENERATOR_ITERATOR_TYPE,
   JS_MODULE_TYPE,
   JS_GLOBAL_OBJECT_TYPE,
   JS_BUILTINS_OBJECT_TYPE,
   JS_GLOBAL_PROXY_TYPE,
   JS_ARRAY_TYPE,
   JS_ARRAY_BUFFER_TYPE,
   JS_SET_TYPE,
   JS_MAP_TYPE,
   JS_WEAK_MAP_TYPE,
 
@@ skipping 207 matching lines @@
   V(ExternalIntArray)                          \
   V(ExternalUnsignedIntArray)                  \
   V(ExternalFloatArray)                        \
   V(ExternalDoubleArray)                       \
   V(ExternalPixelArray)                        \
   V(ByteArray)                                 \
   V(FreeSpace)                                 \
   V(JSReceiver)                                \
   V(JSObject)                                  \
   V(JSContextExtensionObject)                  \
+  V(JSGeneratorIterator)                       \
   V(JSModule)                                  \
   V(Map)                                       \
   V(DescriptorArray)                           \
   V(TransitionArray)                           \
   V(DeoptimizationInputData)                   \
   V(DeoptimizationOutputData)                  \
   V(DependentCode)                            \
   V(TypeFeedbackCells)                         \
   V(FixedArray)                                \
   V(FixedDoubleArray)                          \
@@ skipping 5265 matching lines @@
       ((kNative + kCompilerHintsSmiTagSize) / kBitsPerByte);
 #else
 #error Unknown byte ordering
 #endif
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(SharedFunctionInfo);
 };
 
 
+// Representation for generator iterators.
+class JSGeneratorIterator: public JSObject {
+ public:
+  // [function]: The function corresponding to this iterator.
+  DECL_ACCESSORS(function, JSFunction)
+
+  // [context]: The context of the suspended computation, or Smi 0.
+  DECL_ACCESSORS(context, Object)
+
+  // [continuation]: Offset into code of continuation.
+  inline int continuation();
+  inline void set_continuation(int continuation);
+
+  // [operands]: Saved operand stack: FixedArray or Smi 0.
+  DECL_ACCESSORS(operand_stack, Object)
+
+  // Casting.
+  static inline JSGeneratorIterator* cast(Object* obj);
+
+  // Dispatched behavior.
+  DECLARE_PRINTER(JSGeneratorIterator)
+  DECLARE_VERIFIER(JSGeneratorIterator)
+
+  // Layout description.
+  static const int kFunctionOffset = JSObject::kHeaderSize;
+  static const int kContextOffset = kFunctionOffset + kPointerSize;
+  static const int kContinuationOffset = kContextOffset + kPointerSize;
+  static const int kOperandStackOffset = kContinuationOffset + kPointerSize;
+  static const int kSize = kOperandStackOffset + kPointerSize;
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(JSGeneratorIterator);
+};
+
+
 // Representation for module instance objects.
 class JSModule: public JSObject {
  public:
   // [context]: the context holding the module's locals, or undefined if none.
   DECL_ACCESSORS(context, Object)
 
   // [scope_info]: Scope info.
   DECL_ACCESSORS(scope_info, ScopeInfo)
 
   // Casting.
@@ skipping 3050 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_