Function VariadicCall

source/script_expression.cpp:1595–1647

ResultType VariadicCall(IObject *aObj, IObject_Invoke_PARAMS_DECL)
{
	IObject *param_obj = nullptr; // Vararg object passed by caller.
	Array *param_array = nullptr; // Array of parameters, either the same as param_obj or the result of enumeration.
	ExprTokenType* token = nullptr; // Used for variadic calls.

	ExprTokenType *rvalue = IS_INVOKE_SET ? aParam[--aParamCount] : nullptr;

	--aParamCount; // Exclude param_obj from aParamCount, so it's the count of normal params.
	param_obj = TokenToObject(*aParam[aParamCount]);
	// It might be more correct to use the enumerator even for Array, but that could be slow.
	// Future changes might enable efficient detection of a custom __Enum method, allowing
	// us to take the more efficient path most times, but still support custom enumeration.
	if (param_array = dynamic_cast<Array *>(param_obj))
		param_array->AddRef();
	else
		if (!(param_array = Array::FromEnumerable(*aParam[aParamCount])))
			return aResultToken.SetExitResult(FAIL);
	int extra_params = param_array->Length();
	if (extra_params > 0)
	{
		// Calculate space required for ...
		size_t space_needed = extra_params * sizeof(ExprTokenType) // ... new param tokens
			+ (aParamCount + extra_params) * sizeof(ExprTokenType *); // ... existing and new param pointers
		if (rvalue)
			space_needed += sizeof(rvalue); // ... extra slot for aRValue
		// Allocate new param list and tokens; tokens first for convenience.
		token = (ExprTokenType *)_malloca(space_needed);
		if (!token)
			return aResultToken.MemoryError();
		ExprTokenType **param_list = (ExprTokenType **)(token + extra_params);
		// Since built-in functions don't have variables we can directly assign to,
		// we need to expand the param object's contents into an array of tokens:
		param_array->ToParams(token, param_list, aParam, aParamCount);
		aParam = param_list;
		aParamCount += extra_params;
	}
	if (rvalue)
		aParam[aParamCount++] = rvalue; // In place of the variadic param.

#ifdef ENABLE_HALF_BAKED_NAMED_PARAMS
	aResultToken.named_params = param_obj;
#endif

	auto result = aObj->Invoke(aResultToken, aFlags, aName, aThisToken, aParam, aParamCount);

	if (param_array)
		param_array->Release();
	if (token)
		_freea(token);
	
	return result;
}