be/src/vec/functions/function_unary_arithmetic.h

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.
// This file is copied from
// https://github.com/ClickHouse/ClickHouse/blob/master/src/Functions/FunctionUnaryArithmetic.h
// and modified by Doris

#pragma once

#include "vec/columns/column_decimal.h"
#include "vec/columns/column_vector.h"
#include "vec/data_types/data_type_decimal.h"
#include "vec/data_types/data_type_number.h"
#include "vec/functions/cast_type_to_either.h"
#include "vec/functions/function.h"
#include "vec/functions/function_helpers.h"

namespace doris::vectorized {

template <typename A, typename Op>
struct UnaryOperationImpl {
    using ResultType = typename Op::ResultType;
    using ColVecA = std::conditional_t<IsDecimalNumber<A>, ColumnDecimal<A>, ColumnVector<A>>;
    using ColVecC = std::conditional_t<IsDecimalNumber<ResultType>, ColumnDecimal<ResultType>,
                                       ColumnVector<ResultType>>;
    using ArrayA = typename ColVecA::Container;
    using ArrayC = typename ColVecC::Container;

    static void NO_INLINE vector(const ArrayA& a, ArrayC& c) {
        size_t size = a.size();
        for (size_t i = 0; i < size; ++i) c[i] = Op::apply(a[i]);
    }

    static void constant(A a, ResultType& c) { c = Op::apply(a); }
};

template <typename>
struct AbsImpl;
template <typename>
struct NegativeImpl;
template <typename>
struct PositiveImpl;

/// Used to indicate undefined operation
struct InvalidType;

template <template <typename> class Op, typename Name>
class FunctionUnaryArithmetic : public IFunction {
    static constexpr bool allow_decimal = std::is_same_v<Op<Int8>, NegativeImpl<Int8>> ||
                                          std::is_same_v<Op<Int8>, AbsImpl<Int8>> ||
                                          std::is_same_v<Op<Int8>, PositiveImpl<Int8>>;

    template <typename F>
    static bool cast_type(const IDataType* type, F&& f) {
        return cast_type_to_either<DataTypeUInt8, DataTypeUInt16, DataTypeUInt32, DataTypeUInt64,
                                   DataTypeInt8, DataTypeInt16, DataTypeInt32, DataTypeInt64,
                                   DataTypeInt128, DataTypeFloat32, DataTypeFloat64,
                                   DataTypeDecimal<Decimal32>, DataTypeDecimal<Decimal64>,
                                   DataTypeDecimal<Decimal128V2>, DataTypeDecimal<Decimal128V3>,
                                   DataTypeDecimal<Decimal256>>(type, std::forward<F>(f));
    }

public:
    static constexpr auto name = Name::name;
    static FunctionPtr create() { return std::make_shared<FunctionUnaryArithmetic>(); }

    String get_name() const override { return name; }

    size_t get_number_of_arguments() const override { return 1; }

    DataTypePtr get_return_type_impl(const DataTypes& arguments) const override {
        DataTypePtr result;
        bool valid = cast_type(arguments[0].get(), [&](const auto& type) {
            using DataType = std::decay_t<decltype(type)>;
            using T0 = typename DataType::FieldType;

            if constexpr (IsDataTypeDecimal<DataType>) {
                if constexpr (!allow_decimal) return false;
                result = std::make_shared<DataType>(type.get_precision(), type.get_scale());
            } else {
                result = std::make_shared<DataTypeNumber<typename Op<T0>::ResultType>>();
            }
            return true;
        });
        if (!valid) {
            throw doris::Exception(ErrorCode::INVALID_ARGUMENT,
                                   "Illegal type {} of argument of function {}",
                                   arguments[0]->get_name(), get_name());
        }
        return result;
    }

    Status execute_impl(FunctionContext* context, Block& block, const ColumnNumbers& arguments,
                        uint32_t result, size_t input_rows_count) const override {
        bool valid =
                cast_type(block.get_by_position(arguments[0]).type.get(), [&](const auto& type) {
                    using DataType = std::decay_t<decltype(type)>;
                    using T0 = typename DataType::FieldType;

                    if constexpr (IsDataTypeDecimal<DataType>) {
                        if constexpr (allow_decimal) {
                            if (auto col = check_and_get_column<ColumnDecimal<T0>>(
                                        block.get_by_position(arguments[0]).column.get())) {
                                auto col_res = ColumnDecimal<typename Op<T0>::ResultType>::create(
                                        0, type.get_scale());
                                auto& vec_res = col_res->get_data();
                                vec_res.resize(col->get_data().size());
                                UnaryOperationImpl<T0, Op<T0>>::vector(col->get_data(), vec_res);
                                block.replace_by_position(result, std::move(col_res));
                                return true;
                            }
                        }
                    } else {
                        if (auto col = check_and_get_column<ColumnVector<T0>>(
                                    block.get_by_position(arguments[0]).column.get())) {
                            auto col_res = ColumnVector<typename Op<T0>::ResultType>::create();
                            auto& vec_res = col_res->get_data();
                            vec_res.resize(col->get_data().size());
                            UnaryOperationImpl<T0, Op<T0>>::vector(col->get_data(), vec_res);
                            block.replace_by_position(result, std::move(col_res));
                            return true;
                        }
                    }

                    return false;
                });
        if (!valid) {
            return Status::RuntimeError("{}'s argument does not match the expected data type",
                                        get_name());
        }
        return Status::OK();
    }
};

} // namespace doris::vectorized