Function ValidateFunctor

source/script2.cpp:17112–17153

ResultType ValidateFunctor(IObject *aFunc, int aParamCount, ResultToken &aResultToken, int *aUseMinParams, bool aShowError)
{
	ASSERT(aFunc);
	__int64 min_params = 0, max_params = INT_MAX;
	auto min_result = aParamCount == -1 ? INVOKE_NOT_HANDLED
		: GetObjectIntProperty(aFunc, _T("MinParams"), min_params, aResultToken, true);
	if (!min_result)
		return FAIL;
	bool has_minparams = min_result != INVOKE_NOT_HANDLED; // For readability.
	if (aUseMinParams) // CallbackCreate's signal to default to MinParams.
	{
		if (!has_minparams)
			return aShowError ? aResultToken.UnknownMemberError(ExprTokenType(aFunc), IT_GET, _T("MinParams")) : CONDITION_FALSE;
		*aUseMinParams = aParamCount = (int)min_params;
	}
	else if (has_minparams && aParamCount < (int)min_params)
		return aShowError ? aResultToken.ValueError(ERR_INVALID_FUNCTOR) : CONDITION_FALSE;
	auto max_result = (aParamCount <= 0 || has_minparams && min_params == aParamCount)
		? INVOKE_NOT_HANDLED // No need to check MaxParams in the above cases.
		: GetObjectIntProperty(aFunc, _T("MaxParams"), max_params, aResultToken, true);
	if (!max_result)
		return FAIL;
	if (max_result != INVOKE_NOT_HANDLED && aParamCount > (int)max_params)
	{
		__int64 is_variadic = 0;
		auto result = GetObjectIntProperty(aFunc, _T("IsVariadic"), is_variadic, aResultToken, true);
		if (!result)
			return FAIL;
		if (!is_variadic) // or not defined.
			return aShowError ? aResultToken.ValueError(ERR_INVALID_FUNCTOR) : CONDITION_FALSE;
	}
	// If either MinParams or MaxParams was confirmed to exist, this is likely a valid
	// function object, so skip the following check for performance.  Otherwise, catch
	// likely errors by checking that the object is callable.
	if (min_result == INVOKE_NOT_HANDLED && max_result == INVOKE_NOT_HANDLED)
		if (Object *obj = dynamic_cast<Object *>(aFunc))
			if (!obj->HasMethod(_T("Call")))
				return aShowError ? aResultToken.UnknownMemberError(ExprTokenType(aFunc), IT_CALL, _T("Call")) : CONDITION_FALSE;
		// Otherwise: COM objects can be callable via DISPID_VALUE.  There's probably
		// no way to determine whether the object supports that without invoking it.
	return OK;
}