be/src/exprs/function/cast/function_cast_decimal.cpp

// Licensed to the Apache Software Foundation (ASF) under one
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// 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,
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// specific language governing permissions and limitations
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#include "core/data_type/data_type_decimal.h"
#include "exprs/function/cast/cast_to_decimal.h"

namespace doris::CastWrapper {

template <typename T>
constexpr static bool type_allow_cast_to_decimal =
        std::is_same_v<T, DataTypeString> || IsDataTypeNumber<T> || IsDataTypeDecimal<T>;

template <typename ToDataType>
WrapperType create_decimal_wrapper(FunctionContext* context, const DataTypePtr& from_type) {
    std::shared_ptr<CastToBase> cast_impl;

    auto make_cast_wrapper = [&](const auto& types) -> bool {
        using Types = std::decay_t<decltype(types)>;
        using FromDataType = typename Types::LeftType;
        if constexpr (type_allow_cast_to_decimal<FromDataType>) {
            if (context->enable_strict_mode()) {
                cast_impl = std::make_shared<
                        CastToImpl<CastModeType::StrictMode, FromDataType, ToDataType>>();
            } else {
                cast_impl = std::make_shared<
                        CastToImpl<CastModeType::NonStrictMode, FromDataType, ToDataType>>();
            }
            return true;
        } else {
            return false;
        }
    };

    if (!call_on_index_and_data_type<void>(from_type->get_primitive_type(), make_cast_wrapper)) {
        return create_unsupport_wrapper(
                fmt::format("CAST AS decimal not supported {}", from_type->get_name()));
    }

    return [cast_impl](FunctionContext* context, Block& block, const ColumnNumbers& arguments,
                       uint32_t result, size_t input_rows_count,
                       const NullMap::value_type* null_map = nullptr) {
        return cast_impl->execute_impl(context, block, arguments, result, input_rows_count,
                                       null_map);
    };
}

WrapperType create_decimal_wrapper(FunctionContext* context, const DataTypePtr& from_type,
                                   PrimitiveType to_type) {
    switch (to_type) {
    case TYPE_DECIMALV2:
        return create_decimal_wrapper<DataTypeDecimalV2>(context, from_type);
    case TYPE_DECIMAL32:
        return create_decimal_wrapper<DataTypeDecimal32>(context, from_type);
    case TYPE_DECIMAL64:
        return create_decimal_wrapper<DataTypeDecimal64>(context, from_type);
    case TYPE_DECIMAL128I:
        return create_decimal_wrapper<DataTypeDecimal128>(context, from_type);
    case TYPE_DECIMAL256:
        return create_decimal_wrapper<DataTypeDecimal256>(context, from_type);
    default:
        return create_unsupport_wrapper(
                fmt::format("CAST AS decimal: unsupported to_type {}", type_to_string(to_type)));
    }
}

} // namespace doris::CastWrapper