src/base/settingsstorage.h

   1 /*
   2  * Bittorrent Client using Qt and libtorrent.
   3  * Copyright (C) 2023  Mike Tzou (Chocobo1)
   4  * Copyright (C) 2016  Vladimir Golovnev <glassez@yandex.ru>
   5  * Copyright (C) 2014  sledgehammer999 <hammered999@gmail.com>
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version 2
  10  * of the License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  20  *
  21  * In addition, as a special exception, the copyright holders give permission to
  22  * link this program with the OpenSSL project's "OpenSSL" library (or with
  23  * modified versions of it that use the same license as the "OpenSSL" library),
  24  * and distribute the linked executables. You must obey the GNU General Public
  25  * License in all respects for all of the code used other than "OpenSSL".  If you
  26  * modify file(s), you may extend this exception to your version of the file(s),
  27  * but you are not obligated to do so. If you do not wish to do so, delete this
  28  * exception statement from your version.
  29  */
  30
  31 #pragma once
  32
  33 #include <type_traits>
  34
  35 #include <QObject>
  36 #include <QReadWriteLock>
  37 #include <QTimer>
  38 #include <QVariant>
  39 #include <QVariantHash>
  40
  41 #include "base/concepts/stringable.h"
  42 #include "utils/string.h"
  43
  44 template <typename T>
  45 concept IsQFlags = std::same_as<T, QFlags<typename T::enum_type>>;
  46
  47 // There are 2 ways for class `T` provide serialization support into `SettingsStorage`:
  48 // 1. If the `T` state is intended for users to edit (via a text editor), then
  49 //    `T` should satisfy `Stringable` concept
  50 // 2. Otherwise, use `Q_DECLARE_METATYPE(T)` and let `QMetaType` handle the serialization
  51 class SettingsStorage final : public QObject
  52 {
  53     Q_OBJECT
  54     Q_DISABLE_COPY_MOVE(SettingsStorage)
  55
  56     SettingsStorage();
  57     ~SettingsStorage();
  58
  59 public:
  60     static void initInstance();
  61     static void freeInstance();
  62     static SettingsStorage *instance();
  63
  64     template <typename T>
  65     T loadValue(const QString &key, const T &defaultValue = {}) const
  66     {
  67         if constexpr (std::same_as<T, QVariant>)
  68         {
  69             // fast path for loading QVariant
  70             return loadValueImpl(key, defaultValue);
  71         }
  72         else if constexpr (Stringable<T>)
  73         {
  74             const QString value = loadValue(key, defaultValue.toString());
  75             return T {value};
  76         }
  77         else if constexpr (std::is_enum_v<T>)
  78         {
  79             const auto value = loadValue<QString>(key);
  80             return Utils::String::toEnum(value, defaultValue);
  81         }
  82         else if constexpr (IsQFlags<T>)
  83         {
  84             const typename T::Int value = loadValue(key, static_cast<typename T::Int>(defaultValue));
  85             return T {value};
  86         }
  87         else
  88         {
  89             const QVariant value = loadValueImpl(key);
  90             // check if retrieved value is convertible to T
  91             return value.template canConvert<T>() ? value.template value<T>() : defaultValue;
  92         }
  93     }
  94
  95     template <typename T>
  96     void storeValue(const QString &key, const T &value)
  97     {
  98         if constexpr (std::same_as<T, QVariant>)
  99             storeValueImpl(key, value);
 100         else if constexpr (Stringable<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>)
 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     bool isEmpty() const;
 113
 114 public slots:
 115     bool save();
 116
 117 private:
 118     QVariant loadValueImpl(const QString &key, const QVariant &defaultValue = {}) const;
 119     void storeValueImpl(const QString &key, const QVariant &value);
 120     void readNativeSettings();
 121     bool writeNativeSettings() const;
 122
 123     static SettingsStorage *m_instance;
 124
 125     const QString m_nativeSettingsName;
 126     bool m_dirty = false;
 127     QVariantHash m_data;
 128     QTimer m_timer;
 129     mutable QReadWriteLock m_lock;
 130 };