lmdbal/src/cursor.h

/*
 * LMDB Abstraction Layer.
 * Copyright (C) 2023  Yury Gubich <blue@macaw.me>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#pragma once

#include <string>

#include "lmdb.h"
#include "base.h"
#include "storage.h"
#include "transaction.h"

namespace LMDBAL {

template <class K, class V>
class Cursor {
    friend class Storage<K, V>;
private:
    enum State {            /**<Cursor state:*/
        closed,             /**<    - closed*/
        openedPublic,       /**<    - opened with public transaction, all storages will be notified about it after it's done*/
        openedPrivate       /**<    - opened with private transaction, only current storage will be notified when cursor is closed*/
    };

public:
    Cursor();
    Cursor(Storage<K, V>* parent);
    Cursor(const Cursor& other) = delete;
    Cursor(Cursor&& other);
    ~Cursor();

    Cursor& operator = (const Cursor& other) = delete;
    Cursor& operator = (Cursor&& other);

    void open();
    void open(const Transaction& transaction);
    void renew();
    void renew(const Transaction& transaction);
    void close();
    bool opened() const;
    bool empty() const;

    void drop();

    std::pair<K, V> first();
    std::pair<K, V> last();
    std::pair<K, V> next();
    std::pair<K, V> prev();
    std::pair<K, V> current() const;
    bool set(const K& target);

    void first(K& key, V& value);
    void last(K& key, V& value);
    void next(K& key, V& value);
    void prev(K& key, V& value);
    void current(K& key, V& value) const;

private:
    void dropped();
    void freed();
    void terminated();
    void operateCursorRead(K& key, V& value, MDB_cursor_op operation, const std::string& methodName, const std::string& operationName) const;

private:
    Storage<K, V>* storage;
    MDB_cursor* cursor;
    State state;
    uint32_t id;

    inline static const std::string openCursorMethodName = "Cursor::open";      /**<\brief member function name, just for exceptions*/
    inline static const std::string closeCursorMethodName = "Cursor::close";    /**<\brief member function name, just for exceptions*/
    inline static const std::string renewCursorMethodName = "Cursor::renew";    /**<\brief member function name, just for exceptions*/

    inline static const std::string firstMethodName = "first";                  /**<\brief member function name, just for exceptions*/
    inline static const std::string lastMethodName = "last";                    /**<\brief member function name, just for exceptions*/
    inline static const std::string nextMethodName = "next";                    /**<\brief member function name, just for exceptions*/
    inline static const std::string prevMethodName = "prev";                    /**<\brief member function name, just for exceptions*/
    inline static const std::string currentMethodName = "current";              /**<\brief member function name, just for exceptions*/
    inline static const std::string setMethodName = "set";                      /**<\brief member function name, just for exceptions*/

    inline static const std::string firstOperationName = "Cursor::first";       /**<\brief member function name, just for exceptions*/
    inline static const std::string lastOperationName = "Cursor::last";         /**<\brief member function name, just for exceptions*/
    inline static const std::string nextOperationName = "Cursor::next";         /**<\brief member function name, just for exceptions*/
    inline static const std::string prevOperationName = "Cursor::prev";         /**<\brief member function name, just for exceptions*/
    inline static const std::string currentOperationName = "Cursor::current";   /**<\brief member function name, just for exceptions*/
};

};


#include "cursor.hpp"