src/base/settingsstorage.h

   1 /*
   2  * Bittorrent Client using Qt and libtorrent.
   3  * Copyright (C) 2016  Vladimir Golovnev <glassez@yandex.ru>
   4  * Copyright (C) 2014  sledgehammer999 <hammered999@gmail.com>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version 2
   9  * of the License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  19  *
  20  * In addition, as a special exception, the copyright holders give permission to
  21  * link this program with the OpenSSL project's "OpenSSL" library (or with
  22  * modified versions of it that use the same license as the "OpenSSL" library),
  23  * and distribute the linked executables. You must obey the GNU General Public
  24  * License in all respects for all of the code used other than "OpenSSL".  If you
  25  * modify file(s), you may extend this exception to your version of the file(s),
  26  * but you are not obligated to do so. If you do not wish to do so, delete this
  27  * exception statement from your version.
  28  */
  29
  30 #pragma once
  31
  32 #include <type_traits>
  33
  34 #include <QObject>
  35 #include <QReadWriteLock>
  36 #include <QTimer>
  37 #include <QVariant>
  38 #include <QVariantHash>
  39
  40 #include "base/interfaces/istringable.h"
  41 #include "utils/string.h"
  42
  43 template <typename T>
  44 struct IsQFlags : std::false_type {};
  45
  46 template <typename T>
  47 struct IsQFlags<QFlags<T>> : std::true_type {};
  48
  49 // There are 2 ways for class `T` provide serialization support into `SettingsStorage`:
  50 // 1. If the `T` state is intended for users to edit (via a text editor), then
  51 //    implement `IStringable` interface
  52 // 2. Otherwise, use `Q_DECLARE_METATYPE(T)` and let `QMetaType` handle the serialization
  53 class SettingsStorage final : public QObject
  54 {
  55     Q_OBJECT
  56     Q_DISABLE_COPY_MOVE(SettingsStorage)
  57
  58     SettingsStorage();
  59     ~SettingsStorage();
  60
  61 public:
  62     static void initInstance();
  63     static void freeInstance();
  64     static SettingsStorage *instance();
  65
  66     template <typename T>
  67     T loadValue(const QString &key, const T &defaultValue = {}) const
  68     {
  69         if constexpr (std::is_base_of_v<IStringable, T>)
  70         {
  71             const QString value = loadValue(key, defaultValue.toString());
  72             return T {value};
  73         }
  74         else if constexpr (std::is_enum_v<T>)
  75         {
  76             const auto value = loadValue<QString>(key);
  77             return Utils::String::toEnum(value, defaultValue);
  78         }
  79         else if constexpr (IsQFlags<T>::value)
  80         {
  81             const typename T::Int value = loadValue(key, static_cast<typename T::Int>(defaultValue));
  82             return T {value};
  83         }
  84         else if constexpr (std::is_same_v<T, QVariant>)
  85         {
  86             // fast path for loading QVariant
  87             return loadValueImpl(key, defaultValue);
  88         }
  89         else
  90         {
  91             const QVariant value = loadValueImpl(key);
  92             // check if retrieved value is convertible to T
  93             return value.template canConvert<T>() ? value.template value<T>() : defaultValue;
  94         }
  95     }
  96
  97     template <typename T>
  98     void storeValue(const QString &key, const T &value)
  99     {
 100         if constexpr (std::is_base_of_v<IStringable, T>)
 101             storeValueImpl(key, value.toString());
 102         else if constexpr (std::is_enum_v<T>)
 103             storeValueImpl(key, Utils::String::fromEnum(value));
 104         else if constexpr (IsQFlags<T>::value)
 105             storeValueImpl(key, static_cast<typename T::Int>(value));
 106         else
 107             storeValueImpl(key, QVariant::fromValue(value));
 108     }
 109
 110     void removeValue(const QString &key);
 111     bool hasKey(const QString &key) const;
 112
 113 public slots:
 114     bool save();
 115
 116 private:
 117     QVariant loadValueImpl(const QString &key, const QVariant &defaultValue = {}) const;
 118     void storeValueImpl(const QString &key, const QVariant &value);
 119     void readNativeSettings();
 120     bool writeNativeSettings() const;
 121
 122     static SettingsStorage *m_instance;
 123
 124     const QString m_nativeSettingsName;
 125     bool m_dirty = false;
 126     QVariantHash m_data;
 127     QTimer m_timer;
 128     mutable QReadWriteLock m_lock;
 129 };