be/src/vec/functions/hll_empty.cpp

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// to you under the Apache License, Version 2.0 (the
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//
//   http://www.apache.org/licenses/LICENSE-2.0
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#include <algorithm>
#include <memory>
#include <utility>

#include "olap/hll.h"
#include "vec/columns/column_complex.h"
#include "vec/data_types/data_type_hll.h"
#include "vec/functions/function_const.h"
#include "vec/functions/simple_function_factory.h"

namespace doris::vectorized {

struct HLLEmptyImpl {
    static constexpr auto name = "hll_empty";
    using ReturnColVec = ColumnHLL;
    static auto get_return_type() { return std::make_shared<DataTypeHLL>(); }
    static HyperLogLog init_value() { return HyperLogLog {}; }
};

using FunctionHLLEmpty = FunctionConst<HLLEmptyImpl, false>;

void register_function_hll_empty(SimpleFunctionFactory& factory) {
    factory.register_function<FunctionHLLEmpty>();
}

} // namespace doris::vectorized