expression_ptr.h

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/*
 * Copyright 2026 MusicScience37 (Kenta Kabashima)
 *
 * Licensed 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 <memory>
 
#include "func_sketch/expressions/expression.h"
#include "func_sketch/expressions/expression_memory_pool.h"
 
namespace func_sketch::expressions {

class ExpressionPtr {
public:
    ExpressionPtr(Expression* expression,
        std::unique_ptr<ExpressionMemoryPool> memory_pool) noexcept
        : expression_(expression, Deleter(std::move(memory_pool))) {}

    ExpressionPtr() noexcept = default;

    void reset() noexcept {
        expression_ = std::unique_ptr<Expression, Deleter>(nullptr, Deleter());
    }

    [[nodiscard]] Expression* get() const noexcept { return expression_.get(); }

    [[nodiscard]] Expression& operator*() const noexcept {
        return *expression_;
    }

    [[nodiscard]] Expression* operator->() const noexcept {
        return expression_.get();
    }
 
private:
    class Deleter {
    public:
        explicit Deleter(
            std::unique_ptr<ExpressionMemoryPool> memory_pool) noexcept
            : memory_pool_(std::move(memory_pool)) {}

        Deleter() noexcept = default;

        void operator()(Expression* expression) const noexcept {
            if (expression != nullptr && memory_pool_ != nullptr) {
                memory_pool_->destroy(expression);
            }
        }
 
    private:
        std::unique_ptr<ExpressionMemoryPool> memory_pool_;
    };

    std::unique_ptr<Expression, Deleter> expression_;
};
 
}  // namespace func_sketch::expressions