just some thoughts about serializer

database.h

@@ -30,6 +30,8 @@ namespace Core {
 class DataBase
 {
     class _Table;
+    template<class T>
+    class Serializer;
 public:
     template <class K, class V>
     class Table;

main.cpp

@@ -3,6 +3,28 @@
 #include "database.h"
 #include "table.h"
 
+
+template<class T>
+class Serializer {
+public:
+    Serializer(const T& value):val(value) {}
+
+    void print() {
+        std::cout << val << std::endl;
+    }
+
+    T val;
+};
+
+
+template<>
+class Serializer<int> {
+public:
+    Serializer(int v): value(v) {}
+
+    int value;
+};
+
 int main(int argc, char **argv) {
 
     Core::DataBase base("test1");
@@ -13,5 +35,7 @@ int main(int argc, char **argv) {
 
     table1->addRecord(1, 2);
 
+
+
     return 0;
 }

serializer.h

@@ -0,0 +1,52 @@
+// Squawk messenger. 
+// Copyright (C) 2019  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/>.
+
+#ifndef CORE_DATABASE_SERIALIZER_H
+#define CORE_DATABASE_SERIALIZER_H
+
+#include <QByteArray>
+#include <QBuffer>
+#include <QDataStream>
+
+#include "database.h"
+
+namespace Core {
+
+template<class T>
+class DataBase::Serializer
+{
+public:
+    Serializer();
+    Serializer(const T& value);
+    ~Serializer();
+
+    MDB_val setData(const T& value);
+    MDB_val getData();
+    void clear();
+
+private:
+    void _setData(const T& value);
+
+
+private:
+    QByteArray bytes;
+    QBuffer buffer;
+    QDataStream stream;
+};
+
+}
+
+#endif // CORE_DATABASE_SERIALIZER_H

serializer.hpp

@@ -0,0 +1,70 @@
+// Squawk messenger. 
+// Copyright (C) 2019  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/>.
+
+#include "serializer.h"
+
+template<class T>
+Core::DataBase::Serializer<T>::Serializer() :
+    bytes(),
+    buffer(&bytes),
+    stream(&buffer)
+{
+    buffer.open(QIODevice::WriteOnly);
+}
+
+template<class T>
+Core::DataBase::Serializer<T>::Serializer(const T& value) :
+    bytes(),
+    buffer(&bytes),
+    stream(&buffer)
+{
+    buffer.open(QIODevice::WriteOnly);
+    _setValue(value);
+}
+
+template<class T>
+Core::DataBase::Serializer<T>::~Serializer() {
+    buffer.close();
+}
+
+template<class T>
+MDB_val Core::DataBase::Serializer<T>::setData(const T& value) {
+    clear();
+    _setValue(value);
+    return getValue();
+}
+
+template<class T>
+void Core::DataBase::Serializer<T>::_setData(const T& value) {
+    stream << value;
+}
+
+template<class T>
+void Core::DataBase::Serializer<T>::clear() {
+    if (buffer.pos() > 0) {
+        buffer.seek(0);
+    }
+}
+
+template<class T>
+MDB_val Core::DataBase::Serializer<T>::getData() {
+    MDB_val val;
+
+    val.mv_size = buffer.pos();
+    val.mv_data = (uint8_t*)bytes.data();
+
+    return val;
+}

table.h

@@ -18,6 +18,7 @@
 #define CORE_TABLE_H
 
 #include "database.h"
+#include "serializer.h"
 
 namespace Core {
 
@@ -44,16 +45,14 @@ public:
     void changeRecord(const K& key, const V& value);
     void removeRecord(const K& key);
     V getRecord(const K& key) const;
+
+private:
+    Serializer<K> keySerializer;
+    Serializer<V> valueSerializer;
 };
 
 }
 
-MDB_val& operator << (MDB_val& data, const QString& value);
-MDB_val& operator >> (MDB_val& data, QString& value);
-
-MDB_val& operator << (MDB_val& data, const uint32_t& value);
-MDB_val& operator >> (MDB_val& data, uint32_t& value);
-
 namespace std {
     std::string to_string(const QString& str);
 }

table.hpp

@@ -22,7 +22,9 @@
 
 template<typename K, typename V>
 Core::DataBase::Table<K, V>::Table(const std::string& p_name, Core::DataBase* parent):
-    _Table(p_name, parent)
+    _Table(p_name, parent),
+    keySerializer(),
+    valueSerializer()
 {
 }
 
@@ -36,9 +38,8 @@ void Core::DataBase::Table<K, V>::addRecord(const K& key, const V& value) {
         throw Closed("addRecord", db->name, name);
     }
 
-    MDB_val lmdbKey, lmdbData;
-    lmdbKey << key;
-    lmdbData << value;
+    MDB_val lmdbKey = keySerializer.setData(key);
+    MDB_val lmdbData = valueSerializer.setData(value);
     MDB_txn *txn;
     mdb_txn_begin(db->environment, NULL, 0, &txn);
     int rc;
@@ -63,9 +64,8 @@ void Core::DataBase::Table<K, V>::changeRecord(const K& key, const V& value) {
         throw Closed("changeRecord", db->name, name);
     }
 
-    MDB_val lmdbKey, lmdbData;
-    lmdbKey << key;
-    lmdbData << value;
+    MDB_val lmdbKey = keySerializer.setData(key);
+    MDB_val lmdbData = valueSerializer.setData(value);
     MDB_txn *txn;
     mdb_txn_begin(db->environment, NULL, 0, &txn);
     int rc;
@@ -86,8 +86,8 @@ V Core::DataBase::Table<K, V>::getRecord(const K& key) const {
         throw Closed("getRecord", db->name, name);
     }
 
-    MDB_val lmdbKey, lmdbData;
-    lmdbKey << key;
+    MDB_val lmdbKey = keySerializer.setData(key);
+    MDB_val lmdbData;
 
     MDB_txn *txn;
     int rc;
@@ -115,8 +115,7 @@ void Core::DataBase::Table<K, V>::removeRecord(const K& key) {
         throw Closed("removeRecord", db->name, name);
     }
 
-    MDB_val lmdbKey;
-    lmdbKey << key;
+    MDB_val lmdbKey = keySerializer.setData(key);
 
     MDB_txn *txn;
     int rc;
@@ -134,27 +133,6 @@ void Core::DataBase::Table<K, V>::removeRecord(const K& key) {
     }
 }
 
-MDB_val& operator << (MDB_val& data, const QString& value) {
-    QByteArray ba = value.toUtf8();
-    data.mv_size = ba.size();
-    data.mv_data = ba.data();
-    return data;
-}
-MDB_val& operator >> (MDB_val& data, QString& value) {
-    value = QString::fromUtf8((const char*)data.mv_data, data.mv_size);
-    return data;
-}
-
-MDB_val& operator << (MDB_val& data, const uint32_t& value) {
-    data.mv_size = 4;
-    data.mv_data = &value;
-    return data;
-}
-MDB_val& operator >> (MDB_val& data, uint32_t& value) {
-    std::memcpy(&value, data.mv_data, data.mv_size);
-    return data;
-}
-
 std::string std::to_string(const QString& str) {
     return str.toStdString();
 }