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 {            
        closed,             
        openedPublic,       
        openedPrivate       
    };
 
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";      
    inline static const std::string closeCursorMethodName = "Cursor::close";    
    inline static const std::string renewCursorMethodName = "Cursor::renew";    
    inline static const std::string firstMethodName = "first";                  
    inline static const std::string lastMethodName = "last";                    
    inline static const std::string nextMethodName = "next";                    
    inline static const std::string prevMethodName = "prev";                    
    inline static const std::string currentMethodName = "current";              
    inline static const std::string setMethodName = "set";                      
    inline static const std::string firstOperationName = "Cursor::first";       
    inline static const std::string lastOperationName = "Cursor::last";         
    inline static const std::string nextOperationName = "Cursor::next";         
    inline static const std::string prevOperationName = "Cursor::prev";         
    inline static const std::string currentOperationName = "Cursor::current";   
};
 
};
 
 
#include "cursor.hpp"