root/src/accessors.cc

DEFINITIONS

1. FindInPrototypeChain
2. IllegalSetter
3. IllegalGetAccessor
4. ReadOnlySetAccessor
5. ArrayGetLength
6. FlattenNumber
7. ArraySetLength
8. StringGetLength
9. ScriptGetSource
10. ScriptGetName
11. ScriptGetId
12. ScriptGetLineOffset
13. ScriptGetColumnOffset
14. ScriptGetData
15. ScriptGetType
16. ScriptGetCompilationType
17. ScriptGetLineEnds
18. ScriptGetContextData
19. ScriptGetEvalFromScript
20. ScriptGetEvalFromScriptPosition
21. ScriptGetEvalFromFunctionName
22. FunctionGetPrototype
23. FunctionSetPrototype
24. FunctionGetLength
25. FunctionGetName
26. ConstructArgumentsObjectForInlinedFunction
27. FunctionGetArguments
28. CheckNonStrictCallerOrThrow
29. index_
30. next
31. Find
32. GetFunctions
33. FunctionGetCaller
34. ObjectGetPrototype
35. ObjectSetPrototype
36. ModuleGetExport
37. ModuleSetExport
38. MakeModuleExport

// 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
//       with the distribution.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "v8.h"
#include "accessors.h"

#include "contexts.h"
#include "deoptimizer.h"
#include "execution.h"
#include "factory.h"
#include "frames-inl.h"
#include "isolate.h"
#include "list-inl.h"
#include "property-details.h"

namespace v8 {
namespace internal {


template <class C>
static C* FindInPrototypeChain(Object* obj, bool* found_it) {
  ASSERT(!*found_it);
  Heap* heap = HEAP;
  while (!Is<C>(obj)) {
    if (obj == heap->null_value()) return NULL;
    obj = obj->GetPrototype();
  }
  *found_it = true;
  return C::cast(obj);
}


// Entry point that never should be called.
MaybeObject* Accessors::IllegalSetter(JSObject*, Object*, void*) {
  UNREACHABLE();
  return NULL;
}


Object* Accessors::IllegalGetAccessor(Object* object, void*) {
  UNREACHABLE();
  return object;
}


MaybeObject* Accessors::ReadOnlySetAccessor(JSObject*, Object* value, void*) {
  // According to ECMA-262, section 8.6.2.2, page 28, setting
  // read-only properties must be silently ignored.
  return value;
}


//
// Accessors::ArrayLength
//


MaybeObject* Accessors::ArrayGetLength(Object* object, void*) {
  // Traverse the prototype chain until we reach an array.
  bool found_it = false;
  JSArray* holder = FindInPrototypeChain<JSArray>(object, &found_it);
  if (!found_it) return Smi::FromInt(0);
  return holder->length();
}


// The helper function will 'flatten' Number objects.
Object* Accessors::FlattenNumber(Object* value) {
  if (value->IsNumber() || !value->IsJSValue()) return value;
  JSValue* wrapper = JSValue::cast(value);
  ASSERT(Isolate::Current()->context()->global_context()->number_function()->
      has_initial_map());
  Map* number_map = Isolate::Current()->context()->global_context()->
      number_function()->initial_map();
  if (wrapper->map() == number_map) return wrapper->value();
  return value;
}


MaybeObject* Accessors::ArraySetLength(JSObject* object, Object* value, void*) {
  Isolate* isolate = object->GetIsolate();

  // This means one of the object's prototypes is a JSArray and the
  // object does not have a 'length' property.  Calling SetProperty
  // causes an infinite loop.
  if (!object->IsJSArray()) {
    return object->SetLocalPropertyIgnoreAttributes(
        isolate->heap()->length_symbol(), value, NONE);
  }

  value = FlattenNumber(value);

  // Need to call methods that may trigger GC.
  HandleScope scope(isolate);

  // Protect raw pointers.
  Handle<JSObject> object_handle(object, isolate);
  Handle<Object> value_handle(value, isolate);

  bool has_exception;
  Handle<Object> uint32_v = Execution::ToUint32(value_handle, &has_exception);
  if (has_exception) return Failure::Exception();
  Handle<Object> number_v = Execution::ToNumber(value_handle, &has_exception);
  if (has_exception) return Failure::Exception();

  if (uint32_v->Number() == number_v->Number()) {
    return Handle<JSArray>::cast(object_handle)->SetElementsLength(*uint32_v);
  }
  return isolate->Throw(
      *isolate->factory()->NewRangeError("invalid_array_length",
                                         HandleVector<Object>(NULL, 0)));
}


const AccessorDescriptor Accessors::ArrayLength = {
  ArrayGetLength,
  ArraySetLength,
};


//
// Accessors::StringLength
//


MaybeObject* Accessors::StringGetLength(Object* object, void*) {
  Object* value = object;
  if (object->IsJSValue()) value = JSValue::cast(object)->value();
  if (value->IsString()) return Smi::FromInt(String::cast(value)->length());
  // If object is not a string we return 0 to be compatible with WebKit.
  // Note: Firefox returns the length of ToString(object).
  return Smi::FromInt(0);
}


const AccessorDescriptor Accessors::StringLength = {
  StringGetLength,
  IllegalSetter,
};


//
// Accessors::ScriptSource
//


MaybeObject* Accessors::ScriptGetSource(Object* object, void*) {
  Object* script = JSValue::cast(object)->value();
  return Script::cast(script)->source();
}


const AccessorDescriptor Accessors::ScriptSource = {
  ScriptGetSource,
  IllegalSetter,
};


//
// Accessors::ScriptName
//


MaybeObject* Accessors::ScriptGetName(Object* object, void*) {
  Object* script = JSValue::cast(object)->value();
  return Script::cast(script)->name();
}


const AccessorDescriptor Accessors::ScriptName = {
  ScriptGetName,
  IllegalSetter,
};


//
// Accessors::ScriptId
//


MaybeObject* Accessors::ScriptGetId(Object* object, void*) {
  Object* script = JSValue::cast(object)->value();
  return Script::cast(script)->id();
}


const AccessorDescriptor Accessors::ScriptId = {
  ScriptGetId,
  IllegalSetter,
};


//
// Accessors::ScriptLineOffset
//


MaybeObject* Accessors::ScriptGetLineOffset(Object* object, void*) {
  Object* script = JSValue::cast(object)->value();
  return Script::cast(script)->line_offset();
}


const AccessorDescriptor Accessors::ScriptLineOffset = {
  ScriptGetLineOffset,
  IllegalSetter,
};


//
// Accessors::ScriptColumnOffset
//


MaybeObject* Accessors::ScriptGetColumnOffset(Object* object, void*) {
  Object* script = JSValue::cast(object)->value();
  return Script::cast(script)->column_offset();
}


const AccessorDescriptor Accessors::ScriptColumnOffset = {
  ScriptGetColumnOffset,
  IllegalSetter,
};


//
// Accessors::ScriptData
//


MaybeObject* Accessors::ScriptGetData(Object* object, void*) {
  Object* script = JSValue::cast(object)->value();
  return Script::cast(script)->data();
}


const AccessorDescriptor Accessors::ScriptData = {
  ScriptGetData,
  IllegalSetter,
};


//
// Accessors::ScriptType
//


MaybeObject* Accessors::ScriptGetType(Object* object, void*) {
  Object* script = JSValue::cast(object)->value();
  return Script::cast(script)->type();
}


const AccessorDescriptor Accessors::ScriptType = {
  ScriptGetType,
  IllegalSetter,
};


//
// Accessors::ScriptCompilationType
//


MaybeObject* Accessors::ScriptGetCompilationType(Object* object, void*) {
  Object* script = JSValue::cast(object)->value();
  return Script::cast(script)->compilation_type();
}


const AccessorDescriptor Accessors::ScriptCompilationType = {
  ScriptGetCompilationType,
  IllegalSetter,
};


//
// Accessors::ScriptGetLineEnds
//


MaybeObject* Accessors::ScriptGetLineEnds(Object* object, void*) {
  JSValue* wrapper = JSValue::cast(object);
  Isolate* isolate = wrapper->GetIsolate();
  HandleScope scope(isolate);
  Handle<Script> script(Script::cast(wrapper->value()), isolate);
  InitScriptLineEnds(script);
  ASSERT(script->line_ends()->IsFixedArray());
  Handle<FixedArray> line_ends(FixedArray::cast(script->line_ends()));
  // We do not want anyone to modify this array from JS.
  ASSERT(*line_ends == isolate->heap()->empty_fixed_array() ||
         line_ends->map() == isolate->heap()->fixed_cow_array_map());
  Handle<JSArray> js_array =
      isolate->factory()->NewJSArrayWithElements(line_ends);
  return *js_array;
}


const AccessorDescriptor Accessors::ScriptLineEnds = {
  ScriptGetLineEnds,
  IllegalSetter,
};


//
// Accessors::ScriptGetContextData
//


MaybeObject* Accessors::ScriptGetContextData(Object* object, void*) {
  Object* script = JSValue::cast(object)->value();
  return Script::cast(script)->context_data();
}


const AccessorDescriptor Accessors::ScriptContextData = {
  ScriptGetContextData,
  IllegalSetter,
};


//
// Accessors::ScriptGetEvalFromScript
//


MaybeObject* Accessors::ScriptGetEvalFromScript(Object* object, void*) {
  Object* script = JSValue::cast(object)->value();
  if (!Script::cast(script)->eval_from_shared()->IsUndefined()) {
    Handle<SharedFunctionInfo> eval_from_shared(
        SharedFunctionInfo::cast(Script::cast(script)->eval_from_shared()));

    if (eval_from_shared->script()->IsScript()) {
      Handle<Script> eval_from_script(Script::cast(eval_from_shared->script()));
      return *GetScriptWrapper(eval_from_script);
    }
  }
  return HEAP->undefined_value();
}


const AccessorDescriptor Accessors::ScriptEvalFromScript = {
  ScriptGetEvalFromScript,
  IllegalSetter,
};


//
// Accessors::ScriptGetEvalFromScriptPosition
//


MaybeObject* Accessors::ScriptGetEvalFromScriptPosition(Object* object, void*) {
  HandleScope scope;
  Handle<Script> script(Script::cast(JSValue::cast(object)->value()));

  // If this is not a script compiled through eval there is no eval position.
  int compilation_type = Smi::cast(script->compilation_type())->value();
  if (compilation_type != Script::COMPILATION_TYPE_EVAL) {
    return HEAP->undefined_value();
  }

  // Get the function from where eval was called and find the source position
  // from the instruction offset.
  Handle<Code> code(SharedFunctionInfo::cast(
      script->eval_from_shared())->code());
  return Smi::FromInt(code->SourcePosition(code->instruction_start() +
                      script->eval_from_instructions_offset()->value()));
}


const AccessorDescriptor Accessors::ScriptEvalFromScriptPosition = {
  ScriptGetEvalFromScriptPosition,
  IllegalSetter,
};


//
// Accessors::ScriptGetEvalFromFunctionName
//


MaybeObject* Accessors::ScriptGetEvalFromFunctionName(Object* object, void*) {
  Object* script = JSValue::cast(object)->value();
  Handle<SharedFunctionInfo> shared(SharedFunctionInfo::cast(
      Script::cast(script)->eval_from_shared()));


  // Find the name of the function calling eval.
  if (!shared->name()->IsUndefined()) {
    return shared->name();
  } else {
    return shared->inferred_name();
  }
}


const AccessorDescriptor Accessors::ScriptEvalFromFunctionName = {
  ScriptGetEvalFromFunctionName,
  IllegalSetter,
};


//
// Accessors::FunctionPrototype
//


MaybeObject* Accessors::FunctionGetPrototype(Object* object, void*) {
  Heap* heap = Isolate::Current()->heap();
  bool found_it = false;
  JSFunction* function = FindInPrototypeChain<JSFunction>(object, &found_it);
  if (!found_it) return heap->undefined_value();
  while (!function->should_have_prototype()) {
    found_it = false;
    function = FindInPrototypeChain<JSFunction>(object->GetPrototype(),
                                                &found_it);
    // There has to be one because we hit the getter.
    ASSERT(found_it);
  }

  if (!function->has_prototype()) {
    Object* prototype;
    { MaybeObject* maybe_prototype = heap->AllocateFunctionPrototype(function);
      if (!maybe_prototype->ToObject(&prototype)) return maybe_prototype;
    }
    Object* result;
    { MaybeObject* maybe_result = function->SetPrototype(prototype);
      if (!maybe_result->ToObject(&result)) return maybe_result;
    }
  }
  return function->prototype();
}


MaybeObject* Accessors::FunctionSetPrototype(JSObject* object,
                                             Object* value,
                                             void*) {
  Heap* heap = object->GetHeap();
  bool found_it = false;
  JSFunction* function = FindInPrototypeChain<JSFunction>(object, &found_it);
  if (!found_it) return heap->undefined_value();
  if (!function->should_have_prototype()) {
    // Since we hit this accessor, object will have no prototype property.
    return object->SetLocalPropertyIgnoreAttributes(heap->prototype_symbol(),
                                                    value,
                                                    NONE);
  }

  Object* prototype;
  { MaybeObject* maybe_prototype = function->SetPrototype(value);
    if (!maybe_prototype->ToObject(&prototype)) return maybe_prototype;
  }
  ASSERT(function->prototype() == value);
  return function;
}


const AccessorDescriptor Accessors::FunctionPrototype = {
  FunctionGetPrototype,
  FunctionSetPrototype,
};


//
// Accessors::FunctionLength
//


MaybeObject* Accessors::FunctionGetLength(Object* object, void*) {
  bool found_it = false;
  JSFunction* function = FindInPrototypeChain<JSFunction>(object, &found_it);
  if (!found_it) return Smi::FromInt(0);
  // Check if already compiled.
  if (!function->shared()->is_compiled()) {
    // If the function isn't compiled yet, the length is not computed
    // correctly yet. Compile it now and return the right length.
    HandleScope scope;
    Handle<JSFunction> handle(function);
    if (!JSFunction::CompileLazy(handle, KEEP_EXCEPTION)) {
      return Failure::Exception();
    }
    return Smi::FromInt(handle->shared()->length());
  } else {
    return Smi::FromInt(function->shared()->length());
  }
}


const AccessorDescriptor Accessors::FunctionLength = {
  FunctionGetLength,
  ReadOnlySetAccessor,
};


//
// Accessors::FunctionName
//


MaybeObject* Accessors::FunctionGetName(Object* object, void*) {
  bool found_it = false;
  JSFunction* holder = FindInPrototypeChain<JSFunction>(object, &found_it);
  if (!found_it) return HEAP->undefined_value();
  return holder->shared()->name();
}


const AccessorDescriptor Accessors::FunctionName = {
  FunctionGetName,
  ReadOnlySetAccessor,
};


//
// Accessors::FunctionArguments
//


static MaybeObject* ConstructArgumentsObjectForInlinedFunction(
    JavaScriptFrame* frame,
    Handle<JSFunction> inlined_function,
    int inlined_frame_index) {
  Factory* factory = Isolate::Current()->factory();
  Vector<SlotRef> args_slots =
      SlotRef::ComputeSlotMappingForArguments(
          frame,
          inlined_frame_index,
          inlined_function->shared()->formal_parameter_count());
  int args_count = args_slots.length();
  Handle<JSObject> arguments =
      factory->NewArgumentsObject(inlined_function, args_count);
  Handle<FixedArray> array = factory->NewFixedArray(args_count);
  for (int i = 0; i < args_count; ++i) {
    Handle<Object> value = args_slots[i].GetValue();
    array->set(i, *value);
  }
  arguments->set_elements(*array);
  args_slots.Dispose();

  // Return the freshly allocated arguments object.
  return *arguments;
}


MaybeObject* Accessors::FunctionGetArguments(Object* object, void*) {
  Isolate* isolate = Isolate::Current();
  HandleScope scope(isolate);
  bool found_it = false;
  JSFunction* holder = FindInPrototypeChain<JSFunction>(object, &found_it);
  if (!found_it) return isolate->heap()->undefined_value();
  Handle<JSFunction> function(holder, isolate);

  if (function->shared()->native()) return isolate->heap()->null_value();
  // Find the top invocation of the function by traversing frames.
  List<JSFunction*> functions(2);
  for (JavaScriptFrameIterator it(isolate); !it.done(); it.Advance()) {
    JavaScriptFrame* frame = it.frame();
    frame->GetFunctions(&functions);
    for (int i = functions.length() - 1; i >= 0; i--) {
      // Skip all frames that aren't invocations of the given function.
      if (functions[i] != *function) continue;

      if (i > 0) {
        // The function in question was inlined.  Inlined functions have the
        // correct number of arguments and no allocated arguments object, so
        // we can construct a fresh one by interpreting the function's
        // deoptimization input data.
        return ConstructArgumentsObjectForInlinedFunction(frame, function, i);
      }

      if (!frame->is_optimized()) {
        // If there is an arguments variable in the stack, we return that.
        Handle<ScopeInfo> scope_info(function->shared()->scope_info());
        int index = scope_info->StackSlotIndex(
            isolate->heap()->arguments_symbol());
        if (index >= 0) {
          Handle<Object> arguments(frame->GetExpression(index), isolate);
          if (!arguments->IsArgumentsMarker()) return *arguments;
        }
      }

      // If there is no arguments variable in the stack or we have an
      // optimized frame, we find the frame that holds the actual arguments
      // passed to the function.
      it.AdvanceToArgumentsFrame();
      frame = it.frame();

      // Get the number of arguments and construct an arguments object
      // mirror for the right frame.
      const int length = frame->ComputeParametersCount();
      Handle<JSObject> arguments = isolate->factory()->NewArgumentsObject(
          function, length);
      Handle<FixedArray> array = isolate->factory()->NewFixedArray(length);

      // Copy the parameters to the arguments object.
      ASSERT(array->length() == length);
      for (int i = 0; i < length; i++) array->set(i, frame->GetParameter(i));
      arguments->set_elements(*array);

      // Return the freshly allocated arguments object.
      return *arguments;
    }
    functions.Rewind(0);
  }

  // No frame corresponding to the given function found. Return null.
  return isolate->heap()->null_value();
}


const AccessorDescriptor Accessors::FunctionArguments = {
  FunctionGetArguments,
  ReadOnlySetAccessor,
};


//
// Accessors::FunctionCaller
//


static MaybeObject* CheckNonStrictCallerOrThrow(
    Isolate* isolate,
    JSFunction* caller) {
  DisableAssertNoAllocation enable_allocation;
  if (!caller->shared()->is_classic_mode()) {
    return isolate->Throw(
        *isolate->factory()->NewTypeError("strict_caller",
                                          HandleVector<Object>(NULL, 0)));
  }
  return caller;
}


class FrameFunctionIterator {
 public:
  FrameFunctionIterator(Isolate* isolate, const AssertNoAllocation& promise)
      : frame_iterator_(isolate),
        functions_(2),
        index_(0) {
    GetFunctions();
  }
  JSFunction* next() {
    if (functions_.length() == 0) return NULL;
    JSFunction* next_function = functions_[index_];
    index_--;
    if (index_ < 0) {
      GetFunctions();
    }
    return next_function;
  }

  // Iterate through functions until the first occurence of 'function'.
  // Returns true if 'function' is found, and false if the iterator ends
  // without finding it.
  bool Find(JSFunction* function) {
    JSFunction* next_function;
    do {
      next_function = next();
      if (next_function == function) return true;
    } while (next_function != NULL);
    return false;
  }

 private:
  void GetFunctions() {
    functions_.Rewind(0);
    if (frame_iterator_.done()) return;
    JavaScriptFrame* frame = frame_iterator_.frame();
    frame->GetFunctions(&functions_);
    ASSERT(functions_.length() > 0);
    frame_iterator_.Advance();
    index_ = functions_.length() - 1;
  }
  JavaScriptFrameIterator frame_iterator_;
  List<JSFunction*> functions_;
  int index_;
};


MaybeObject* Accessors::FunctionGetCaller(Object* object, void*) {
  Isolate* isolate = Isolate::Current();
  HandleScope scope(isolate);
  AssertNoAllocation no_alloc;
  bool found_it = false;
  JSFunction* holder = FindInPrototypeChain<JSFunction>(object, &found_it);
  if (!found_it) return isolate->heap()->undefined_value();
  if (holder->shared()->native()) return isolate->heap()->null_value();
  Handle<JSFunction> function(holder, isolate);

  FrameFunctionIterator it(isolate, no_alloc);

  // Find the function from the frames.
  if (!it.Find(*function)) {
    // No frame corresponding to the given function found. Return null.
    return isolate->heap()->null_value();
  }

  // Find previously called non-toplevel function.
  JSFunction* caller;
  do {
    caller = it.next();
    if (caller == NULL) return isolate->heap()->null_value();
  } while (caller->shared()->is_toplevel());

  // If caller is a built-in function and caller's caller is also built-in,
  // use that instead.
  JSFunction* potential_caller = caller;
  while (potential_caller != NULL && potential_caller->IsBuiltin()) {
    caller = potential_caller;
    potential_caller = it.next();
  }
  // If caller is bound, return null. This is compatible with JSC, and
  // allows us to make bound functions use the strict function map
  // and its associated throwing caller and arguments.
  if (caller->shared()->bound()) {
    return isolate->heap()->null_value();
  }
  return CheckNonStrictCallerOrThrow(isolate, caller);
}


const AccessorDescriptor Accessors::FunctionCaller = {
  FunctionGetCaller,
  ReadOnlySetAccessor,
};


//
// Accessors::ObjectPrototype
//


MaybeObject* Accessors::ObjectGetPrototype(Object* receiver, void*) {
  Object* current = receiver->GetPrototype();
  while (current->IsJSObject() &&
         JSObject::cast(current)->map()->is_hidden_prototype()) {
    current = current->GetPrototype();
  }
  return current;
}


MaybeObject* Accessors::ObjectSetPrototype(JSObject* receiver,
                                           Object* value,
                                           void*) {
  const bool skip_hidden_prototypes = true;
  // To be consistent with other Set functions, return the value.
  return receiver->SetPrototype(value, skip_hidden_prototypes);
}


const AccessorDescriptor Accessors::ObjectPrototype = {
  ObjectGetPrototype,
  ObjectSetPrototype,
};


//
// Accessors::MakeModuleExport
//

static v8::Handle<v8::Value> ModuleGetExport(
    v8::Local<v8::String> property,
    const v8::AccessorInfo& info) {
  JSModule* instance = JSModule::cast(*v8::Utils::OpenHandle(*info.Holder()));
  Context* context = Context::cast(instance->context());
  ASSERT(context->IsModuleContext());
  int slot = info.Data()->Int32Value();
  Object* value = context->get(slot);
  if (value->IsTheHole()) {
    Handle<String> name = v8::Utils::OpenHandle(*property);
    Isolate* isolate = instance->GetIsolate();
    isolate->ScheduleThrow(
        *isolate->factory()->NewReferenceError("not_defined",
                                               HandleVector(&name, 1)));
    return v8::Handle<v8::Value>();
  }
  return v8::Utils::ToLocal(Handle<Object>(value));
}


static void ModuleSetExport(
    v8::Local<v8::String> property,
    v8::Local<v8::Value> value,
    const v8::AccessorInfo& info) {
  JSModule* instance = JSModule::cast(*v8::Utils::OpenHandle(*info.Holder()));
  Context* context = Context::cast(instance->context());
  ASSERT(context->IsModuleContext());
  int slot = info.Data()->Int32Value();
  Object* old_value = context->get(slot);
  if (old_value->IsTheHole()) {
    Handle<String> name = v8::Utils::OpenHandle(*property);
    Isolate* isolate = instance->GetIsolate();
    isolate->ScheduleThrow(
        *isolate->factory()->NewReferenceError("not_defined",
                                               HandleVector(&name, 1)));
    return;
  }
  context->set(slot, *v8::Utils::OpenHandle(*value));
}


Handle<AccessorInfo> Accessors::MakeModuleExport(
    Handle<String> name,
    int index,
    PropertyAttributes attributes) {
  Factory* factory = name->GetIsolate()->factory();
  Handle<AccessorInfo> info = factory->NewAccessorInfo();
  info->set_property_attributes(attributes);
  info->set_all_can_read(true);
  info->set_all_can_write(true);
  info->set_name(*name);
  info->set_data(Smi::FromInt(index));
  Handle<Object> getter = v8::FromCData(&ModuleGetExport);
  Handle<Object> setter = v8::FromCData(&ModuleSetExport);
  info->set_getter(*getter);
  if (!(attributes & ReadOnly)) info->set_setter(*setter);
  return info;
}


} }  // namespace v8::internal