Method parseArguments

src/TableFunctions/TableFunctionGenerateRandom.cpp:61–136

};

void TableFunctionGenerateRandom::parseArguments(const ASTPtr & ast_function, ContextPtr context)
{
    ASTs & args_func = ast_function->children;

    if (args_func.size() != 1)
        throw Exception(ErrorCodes::LOGICAL_ERROR, "Table function '{}' must have arguments.", getName());

    ASTs & args = args_func.at(0)->children;

    if (args.empty())
        return;

    /// First, check if first argument is structure or seed.
    const auto * first_arg_literal = args[0]->as<const ASTLiteral>();
    bool first_argument_is_structure = !first_arg_literal || first_arg_literal->value.getType() == Field::Types::String;
    size_t max_args = first_argument_is_structure ? 4 : 3;

    if (args.size() > max_args)
        throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH,
                        "Table function '{}' requires at most four (or three if structure is missing) arguments: "
                        " [structure, random_seed, max_string_length, max_array_length].", getName());

    if (first_argument_is_structure)
    {
        /// Allow constant expression for structure argument, it can be generated using generateRandomStructure function.
        args[0] = evaluateConstantExpressionAsLiteral(args[0], context);
    }

    // All the arguments must be literals.
    for (const auto & arg : args)
    {
        const IAST * arg_raw = arg.get();
        if (const auto * func = arg_raw->as<const ASTFunction>(); func && func->name == "_CAST")
            arg_raw = func->arguments->children.at(0).get();

        if (!arg_raw->as<const ASTLiteral>())
        {
            throw Exception(ErrorCodes::BAD_ARGUMENTS,
                "All arguments of table function '{}' except structure argument must be literals. "
                "Got '{}' instead", getName(), arg->formatForErrorMessage());
        }
    }

    size_t arg_index = 0;

    if (first_argument_is_structure)
    {
        /// Parsing first argument as table structure and creating a sample block
        structure = checkAndGetLiteralArgument<String>(args[arg_index], "structure");
        ++arg_index;
    }

    if (args.size() >= arg_index + 1)
    {
        const IAST * arg_raw = args[arg_index].get();
        if (const auto * func = arg_raw->as<const ASTFunction>(); func && func->name == "_CAST")
            arg_raw = func->arguments->children.at(0).get();