serializer.hpp

/*
 * 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 "serializer.h"
 
#include <stdexcept>
#include <limits>
 
#include "base.h"

 * \tparam K type of the keys of the storage
 * \tparam V type of the values of the storage
 */

/**
 * \brief Creates an empty Serializer
 */
template<class T>
LMDBAL::Serializer<T>::Serializer() :
    bytes(),
    buffer(&bytes),
    stream(&buffer)
{
    LMDBAL::detail::applyQDataStreamVersion(stream);
    buffer.open(QIODevice::ReadWrite);
}

template<class T>
LMDBAL::Serializer<T>::Serializer(const T& value) :
    bytes(),
    buffer(&bytes),
    stream(&buffer)
{
    LMDBAL::detail::applyQDataStreamVersion(stream);
    buffer.open(QIODevice::ReadWrite);
    _setData(value);
}

namespace LMDBAL {
    template<class T>
    Serializer<T>::~Serializer() {
        buffer.close();
    }
}

template<class T>
MDB_val LMDBAL::Serializer<T>::setData(const T& value) {
    clear();
    _setData(value);
    return getData();
}

template<class T>
T LMDBAL::Serializer<T>::deserialize(const MDB_val& value) {
    T result;
    deserialize(value, result);
 
    return result;
}

template<class T>
void LMDBAL::Serializer<T>::deserialize(const MDB_val& value, T& result) {
    clear();
 
 
#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
    if (value.mv_size > static_cast<size_t>(std::numeric_limits<qsizetype>::max()))
        throw std::runtime_error("Data size exceeds QByteArray capacity");
 
    QByteArray array(static_cast<const char *>(value.mv_data), static_cast<qsizetype>(value.mv_size));
#else
    if (value.mv_size > static_cast<size_t>(std::numeric_limits<int>::max()))
        throw std::runtime_error("Data size exceeds QByteArray capacity");
 
    QByteArray array(static_cast<const char *>(value.mv_data), static_cast<int>(value.mv_size));
#endif
    QDataStream reader(array);
 
    reader >> result;
}

template<class T>
void LMDBAL::Serializer<T>::_setData(const T& value) {
    stream << value;
}

template<class T>
void LMDBAL::Serializer<T>::setStreamVersion(QDataStream::Version version) {
    stream.setVersion(version);
}

template<class T>
void LMDBAL::Serializer<T>::clear() {
    if (buffer.pos() > 0)
        buffer.seek(0);
}

template<class T>
MDB_val LMDBAL::Serializer<T>::getData() {
    MDB_val val;
 
    val.mv_size = static_cast<size_t>(bytes.size());
    val.mv_data = bytes.data();
 
    return val;
}