MemoryDS.h

/*
╔══════════════════════════════════════════════════════════════════════════════╗
║                       SIMPLY POWERFUL TOOLKIT (SPTK)                         ║
╟──────────────────────────────────────────────────────────────────────────────╢
║  copyright            © 1999-2022 Alexey Parshin. All rights reserved.       ║
║  email                alexeyp@gmail.com                                      ║
╚══════════════════════════════════════════════════════════════════════════════╝
┌──────────────────────────────────────────────────────────────────────────────┐
│   This library is free software; you can redistribute it and/or modify it    │
│   under the terms of the GNU Library General Public License as published by  │
│   the Free Software Foundation; either version 2 of the License, or (at your │
│   option) any later version.                                                 │
│                                                                              │
│   This library 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 Library   │
│   General Public License for more details.                                   │
│                                                                              │
│   You should have received a copy of the GNU Library General Public License  │
│   along with this library; if not, write to the Free Software Foundation,    │
│   Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.               │
│                                                                              │
│   Please report all bugs and problems to alexeyp@gmail.com.                  │
└──────────────────────────────────────────────────────────────────────────────┘
*/
 
#pragma once
 
#include <list>
#include <mutex>
#include <sptk5/DataSource.h>
#include <sptk5/Exception.h>
#include <sptk5/FieldList.h>
#include <sptk5/sptk.h>
 
namespace sptk {
 
class SP_EXPORT MemoryDS
    : public DataSource
{
public:
    MemoryDS() = default;
 
    MemoryDS(const MemoryDS& other) = delete;
 
    MemoryDS(MemoryDS&& other) noexcept
        : m_list(std::move(other.m_list))
        , m_current(std::move(other.m_current))
    {
    }
 
    ~MemoryDS() override = default;
 
    MemoryDS& operator=(const MemoryDS& other) = delete;
 
    MemoryDS& operator=(MemoryDS&& other) noexcept
    {
        std::scoped_lock lock(m_mutex, other.m_mutex);
        m_list = std::move(other.m_list);
        m_current = std::move(other.m_current);
        return *this;
    }
 
    virtual void clear();
 
    virtual FieldList& current()
    {
        std::lock_guard lock(m_mutex);
        return *m_current;
    }
 
    Field& operator[](size_t fieldIndex) override;
 
    Field& operator[](const String& fieldName) override;
 
    size_t fieldCount() const override;
 
    size_t recordCount() const override;
 
    bool readField(const char* fieldName, Variant& fieldValue) override;
 
    bool writeField(const char* fieldName, const Variant& fieldValue) override;
 
    bool open() override;
 
    bool close() override;
 
    bool first() override;
 
    bool next() override;
 
    bool prior() override;
 
    bool last() override;
 
    bool find(const String& fieldName, const Variant& position) override;
 
    bool eof() const override
    {
        std::scoped_lock lock(m_mutex);
        return m_current == m_list.end();
    }
 
    bool empty() const;
 
    std::list<FieldList>& rows()
    {
        std::scoped_lock lock(m_mutex);
        return m_list;
    }
 
    const std::list<FieldList>& rows() const
    {
        std::scoped_lock lock(m_mutex);
        return m_list;
    }
 
    void push_back(FieldList&& fieldList);
 
private:
    mutable std::mutex m_mutex;
    std::list<FieldList> m_list;              // List of the dataset records
    std::list<FieldList>::iterator m_current; // DS iterator
};
} // namespace sptk