Var JavascriptGenerator::EntryReturn(RecyclableObject* function, CallInfo callInfo, ...)
{
PROBE_STACK(function->GetScriptContext(), Js::Constants::MinStackDefault);
ARGUMENTS(args, callInfo);
ScriptContext* scriptContext = function->GetScriptContext();
JavascriptLibrary* library = scriptContext->GetLibrary();
AUTO_TAG_NATIVE_LIBRARY_ENTRY(function, callInfo, L"Generator.prototype.return");
if (!JavascriptGenerator::Is(args[0]))
{
JavascriptError::ThrowTypeErrorVar(scriptContext, JSERR_NeedObjectOfType, L"Generator.prototype.return", L"Generator");
}
JavascriptGenerator* generator = JavascriptGenerator::FromVar(args[0]);
Var input = args.Info.Count > 1 ? args[1] : library->GetUndefined();
if (generator->IsSuspendedStart())
{
generator->SetState(GeneratorState::Completed);
}
if (generator->IsCompleted())
{
return library->CreateIteratorResultObject(input, library->GetTrue());
}
ResumeYieldData yieldData(input, RecyclerNew(scriptContext->GetRecycler(), GeneratorReturnExceptionObject, input, scriptContext));
return generator->CallGenerator(&yieldData, L"Generator.prototype.return");
}
Var JavascriptGenerator::CallGenerator(ResumeYieldData* yieldData, const wchar_t* apiNameForErrorMessage)
{
ScriptContext* scriptContext = this->GetScriptContext();
JavascriptLibrary* library = scriptContext->GetLibrary();
Var result = nullptr;
if (this->IsExecuting())
{
JavascriptError::ThrowTypeError(scriptContext, JSERR_GeneratorAlreadyExecuting, apiNameForErrorMessage);
}
{
// RAII helper to set the state of the generator to completed if an exception is thrown
// or if the save state InterpreterStackFrame is never created implying the generator
// is JITed and returned without ever yielding.
class GeneratorStateHelper
{
JavascriptGenerator* g;
bool didThrow;
public:
GeneratorStateHelper(JavascriptGenerator* g) : g(g), didThrow(true) { g->SetState(GeneratorState::Executing); }
~GeneratorStateHelper() { g->SetState(didThrow || g->frame == nullptr ? GeneratorState::Completed : GeneratorState::Suspended); }
void DidNotThrow() { didThrow = false; }
} helper(this);
Var thunkArgs[] = { this, yieldData };
Arguments arguments(_countof(thunkArgs), thunkArgs);
try
{
result = JavascriptFunction::CallFunction<1>(this->scriptFunction, this->scriptFunction->GetEntryPoint(), arguments);
helper.DidNotThrow();
}
catch (Js::JavascriptExceptionObject* exceptionObj)
{
if (!exceptionObj->IsGeneratorReturnException())
{
throw exceptionObj;
}
result = exceptionObj->GetThrownObject(nullptr);
}
}
if (this->IsCompleted())
{
result = library->CreateIteratorResultObject(result, library->GetTrue());
}
else
{
int nextOffset = this->frame->GetReader()->GetCurrentOffset();
int endOffset = this->frame->GetFunctionBody()->GetByteCode()->GetLength();
if (nextOffset != endOffset - 1)
{
result = library->CreateIteratorResultObjectValueFalse(result);
}
else
{
result = library->CreateIteratorResultObject(result, library->GetTrue());
this->SetState(GeneratorState::Completed);
}
}
return result;
}