be/src/util/defer_op.h

// Licensed to the Apache Software Foundation (ASF) under one
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// 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
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// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

#pragma once

#include <functional>

namespace doris {

// This class is used to defer a function when this object is deconstruct
// A Better Defer operator #5576
// for C++17
// Defer defer {[]{ call something }};
//
// for C++11
// auto op = [] {};
// Defer<decltype<op>> (op);
template <class T>
class Defer {
public:
    Defer(T& closure) : _closure(closure) {}
    Defer(T&& closure) : _closure(std::move(closure)) {}
    ~Defer() { _closure(); }

private:
    T _closure;
};

// Nested use Defer, variable name concat line number
#define DEFER_CONCAT(n, ...) const auto defer##n = doris::Defer([&]() { __VA_ARGS__; })
#define DEFER_FWD(n, ...) DEFER_CONCAT(n, __VA_ARGS__)
#define DEFER(...) DEFER_FWD(__LINE__, __VA_ARGS__)

} // namespace doris