ClickHouse/dbms/AggregateFunctions/parseAggregateFunctionParameters.cpp

#include <AggregateFunctions/parseAggregateFunctionParameters.h>
#include <Parsers/ExpressionListParsers.h>
#include <Parsers/parseQuery.h>
#include <Common/typeid_cast.h>


namespace DB
{

namespace ErrorCodes
{
    extern const int BAD_ARGUMENTS;
    extern const int PARAMETERS_TO_AGGREGATE_FUNCTIONS_MUST_BE_LITERALS;
}

Array getAggregateFunctionParametersArray(const ASTPtr & expression_list, const std::string & error_context)
{
    const ASTs & parameters = expression_list->children;
    if (parameters.empty())
        throw Exception("Parameters list to aggregate functions cannot be empty", ErrorCodes::BAD_ARGUMENTS);

    Array params_row(parameters.size());

    for (size_t i = 0; i < parameters.size(); ++i)
    {
        const auto * literal = parameters[i]->as<ASTLiteral>();
        if (!literal)
        {
            throw Exception("Parameters to aggregate functions must be literals" + (error_context.empty() ? "" : " (in " + error_context +")"),
                        ErrorCodes::PARAMETERS_TO_AGGREGATE_FUNCTIONS_MUST_BE_LITERALS);
        }

        params_row[i] = literal->value;
    }

    return params_row;
}


void getAggregateFunctionNameAndParametersArray(
    const std::string & aggregate_function_name_with_params,
    std::string & aggregate_function_name,
    Array & aggregate_function_parameters,
    const std::string & error_context)
{
    if (aggregate_function_name_with_params.back() != ')')
    {
        aggregate_function_name = aggregate_function_name_with_params;
        aggregate_function_parameters = Array();
        return;
    }

    size_t pos = aggregate_function_name_with_params.find('(');
    if (pos == std::string::npos || pos + 2 >= aggregate_function_name_with_params.size())
        throw Exception(aggregate_function_name_with_params + " doesn't look like aggregate function name in " + error_context + ".",
            ErrorCodes::BAD_ARGUMENTS);

    aggregate_function_name = aggregate_function_name_with_params.substr(0, pos);
    std::string parameters_str = aggregate_function_name_with_params.substr(pos + 1, aggregate_function_name_with_params.size() - pos - 2);

    if (aggregate_function_name.empty())
        throw Exception(aggregate_function_name_with_params + " doesn't look like aggregate function name in " + error_context + ".",
            ErrorCodes::BAD_ARGUMENTS);

    ParserExpressionList params_parser(false);
    ASTPtr args_ast = parseQuery(params_parser,
        parameters_str.data(), parameters_str.data() + parameters_str.size(),
        "parameters of aggregate function in " + error_context, 0);

    if (args_ast->children.empty())
        throw Exception("Incorrect list of parameters to aggregate function "
            + aggregate_function_name, ErrorCodes::BAD_ARGUMENTS);

    aggregate_function_parameters = getAggregateFunctionParametersArray(args_ast);
}

}