/* * Bittorrent Client using Qt and libtorrent. * Copyright (C) 2016 Vladimir Golovnev <glassez@yandex.ru> * * 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 2 * 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, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. * * In addition, as a special exception, the copyright holders give permission to * link this program with the OpenSSL project's "OpenSSL" library (or with * modified versions of it that use the same license as the "OpenSSL" library), * and distribute the linked executables. You must obey the GNU General Public * License in all respects for all of the code used other than "OpenSSL". If you * modify file(s), you may extend this exception to your version of the file(s), * but you are not obligated to do so. If you do not wish to do so, delete this * exception statement from your version. */ #ifndef SETTINGVALUE_H #define SETTINGVALUE_H #include <type_traits> #include <QMetaEnum> #include <QString> #include <QVariant> #include "settingsstorage.h" template <typename T> class CachedSettingValue { public: explicit CachedSettingValue(const char *keyName, const T &defaultValue = T()) : m_keyName(QLatin1String(keyName)) , m_value(loadValue(defaultValue)) { } // The signature of the ProxyFunc should be equivalent to the following: // T proxyFunc(const T &a); template <typename ProxyFunc> explicit CachedSettingValue(const char *keyName, const T &defaultValue , ProxyFunc proxyFunc) : m_keyName(QLatin1String(keyName)) , m_value(proxyFunc(loadValue(defaultValue))) { } T value() const { return m_value; } operator T() const { return value(); } CachedSettingValue<T> &operator=(const T &newValue) { m_value = newValue; storeValue(m_value); return *this; } private: // regular load/save pair template <typename U, typename std::enable_if<!std::is_enum<U>::value, int>::type = 0> U loadValue(const U &defaultValue) { return SettingsStorage::instance()->loadValue(m_keyName, defaultValue).template value<T>(); } template <typename U, typename std::enable_if<!std::is_enum<U>::value, int>::type = 0> void storeValue(const U &value) { SettingsStorage::instance()->storeValue(m_keyName, value); } // load/save pair for an enum // saves literal value of the enum constant, obtained from QMetaEnum template <typename U, typename std::enable_if<std::is_enum<U>::value, int>::type = 0> U loadValue(const U &defaultValue) { static_assert(std::is_same<int, typename std::underlying_type<U>::type>::value, "Enumeration underlying type has to be int"); bool ok = false; const U res = static_cast<U>(QMetaEnum::fromType<U>().keyToValue( SettingsStorage::instance()->loadValue(m_keyName).toString().toLatin1().constData(), &ok)); return ok ? res : defaultValue; } template <typename U, typename std::enable_if<std::is_enum<U>::value, int>::type = 0> void storeValue(const U &value) { SettingsStorage::instance()->storeValue(m_keyName, QString::fromLatin1(QMetaEnum::fromType<U>().valueToKey(static_cast<int>(value)))); } const QString m_keyName; T m_value; }; #endif // SETTINGVALUE_H