// 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.

#pragma once

#include <stddef.h>

#include <memory>

#include "common/status.h"

#include "core/block/column_numbers.h"

#include "core/data_type/data_type.h"

#include "core/data_type/data_type_number.h"

#include "core/types.h"

#include "exprs/function/function.h"

namespace doris {

class FunctionContext;

class Block;

} // namespace doris

namespace doris {

struct UDTFImpl {

static DataTypePtr get_return_type_impl(const DataTypes& arguments) {

return std::make_shared<DataTypeUInt8>(); //just fake return uint8

}

static std::string get_error_msg() {

return "UDTF function do not support this, it's should execute with lateral view.";

}

static DataTypes get_variadic_argument_types() { return {}; }

};

// FunctionFake is use for some function call expr only work at prepare/open phase, do not support execute().

template <typename Impl>

class FunctionFake : public IFunction {

public:

static constexpr auto name = "fake";

static FunctionPtr create() { return std::make_shared<FunctionFake>(); }

String get_name() const override { return name; }

size_t get_number_of_arguments() const override { return 0; }

bool is_variadic() const override { return true; }

DataTypePtr get_return_type_impl(const DataTypes& arguments) const override {

return Impl::get_return_type_impl(arguments);

}

DataTypes get_variadic_argument_types_impl() const override {

return Impl::get_variadic_argument_types();

}

bool use_default_implementation_for_nulls() const override {

if constexpr (std::is_same_v<Impl, UDTFImpl>) {

return false;

}

return true;

}

bool use_default_implementation_for_constants() const override { return false; }

Status execute_impl(FunctionContext* context, Block& block, const ColumnNumbers& arguments,

uint32_t result, size_t input_rows_count) const override {

return Status::NotSupported(Impl::get_error_msg());

}

};

} // namespace doris