Function evlMaxMinValue

src/jrd/SysFunction.cpp:5523–5596

dsc* evlMaxMinValue(thread_db* tdbb, const SysFunction* function, const NestValueArray& args,
	impure_value* impure)
{
	fb_assert(args.getCount() >= 1);
	fb_assert(function->misc != NULL);

	const auto request = tdbb->getRequest();
	HalfStaticArray<const dsc*, 2> argTypes(args.getCount());
	dsc* result = nullptr;

	for (FB_SIZE_T i = 0; i < args.getCount(); ++i)
	{
		const auto value = EVL_expr(tdbb, request, args[i]);
		if (request->req_flags & req_null)	// return NULL if value is NULL
			return nullptr;

		argTypes.add(value);

		if (i == 0)
			result = value;
		else
		{
			switch ((Function)(IPTR) function->misc)
			{
				case funMaxValue:
					if (MOV_compare(tdbb, value, result) > 0)
						result = value;
					break;

				case funMinValue:
					if (MOV_compare(tdbb, value, result) < 0)
						result = value;
					break;

				default:
					fb_assert(false);
			}
		}
	}

	DataTypeUtil(tdbb).makeFromList(&impure->vlu_desc, function->name, argTypes.getCount(), argTypes.begin());

	if (impure->vlu_desc.isText())
	{
		const USHORT length = impure->vlu_desc.dsc_length;

		// Allocate a string block of sufficient size

		auto string = impure->vlu_string;

		if (string && string->str_length < length)
		{
			delete string;
			string = nullptr;
		}

		if (!string)
		{