refs #559, moved cache/settings to blackmisc

src/blackmisc/settingscache.h

@@ -0,0 +1,109 @@
+/* Copyright (C) 2015
+ * swift project Community / Contributors
+ *
+ * This file is part of swift project. It is subject to the license terms in the LICENSE file found in the top-level
+ * directory of this distribution and at http://www.swift-project.org/license.html. No part of swift project,
+ * including this file, may be copied, modified, propagated, or distributed except according to the terms
+ * contained in the LICENSE file.
+ */
+
+//! \file
+
+#ifndef BLACKMISC_SETTINGSCACHE_H
+#define BLACKMISC_SETTINGSCACHE_H
+
+#include "blackmisc/blackmiscexport.h"
+#include "blackmisc/valuecache.h"
+
+namespace BlackMisc
+{
+    /*!
+     * Singleton derived class of CValueCache, for core settings.
+     */
+    class BLACKMISC_EXPORT CSettingsCache : public BlackMisc::CValueCache
+    {
+        Q_OBJECT
+
+    public:
+        //! Return the singleton instance.
+        static CSettingsCache *instance();
+
+        //! The directory where core settings are stored.
+        static const QString &persistentStore();
+
+        //! Save core settings to disk.
+        BlackMisc::CStatusMessage saveToStore(const QString &keyPrefix = {}) const;
+
+        //! Load core settings from disk.
+        BlackMisc::CStatusMessage loadFromStore();
+
+        //! Return the filename where the value with the given key may be stored.
+        static QString filenameForKey(const QString &key);
+
+        //! Return all files where settings may be stored.
+        QStringList enumerateStore() const;
+
+    private:
+        CSettingsCache();
+    };
+
+    /*!
+     * Class template for accessing a specific value in the CSettingsCache.
+     * \tparam Trait A subclass of BlackMisc::CSettingTrait that identifies the value's key and other metadata.
+     */
+    template <typename Trait>
+    class CSetting : public BlackMisc::CCached<typename Trait::type>
+    {
+    public:
+        //! \copydoc BlackMisc::CCached::NotifySlot
+        template <typename T>
+        using NotifySlot = typename BlackMisc::CCached<typename Trait::type>::template NotifySlot<T>;
+
+        //! Constructor.
+        //! \param owner Will be the parent of the internal QObject used to access the value.
+        //! \param slot Slot to call when the value is modified by another object.
+        //!             Must be a void, non-const member function of the owner.
+        template <typename T>
+        CSetting(T *owner, NotifySlot<T> slot = nullptr) :
+            CSetting::CCached(CSettingsCache::instance(), Trait::key(), Trait::isValid, Trait::defaultValue(), owner, slot)
+        {}
+
+        //! Reset the setting to its default value.
+        void setDefault() { this->set(Trait::defaultValue()); }
+
+        //! Return the file that is used for persistence for this value.
+        QString getFilename() const { return CSettingsCache::filenameForKey(this->getKey()); }
+    };
+
+    /*!
+     * Base class for traits to be used as template argument to BlackMisc::CSetting.
+     */
+    template <typename T>
+    struct CSettingTrait
+    {
+        //! Data type of the value.
+        using type = T;
+
+        //! Key string of the value. Reimplemented in derived class.
+        static const char *key() { qFatal("Not implemented"); return ""; }
+
+        //! Validator function. Return true if the argument is valid, false otherwise. Default
+        //! implementation just returns true. Reimplemented in derived class to support validation of the value.
+        static bool isValid(const T &) { return true; }
+
+        //! Return the value to use in case the supplied value does not satisfy the validator.
+        //! Default implementation returns a default-constructed value.
+        static const T &defaultValue() { static const T def {}; return def; }
+
+        //! Deleted default constructor.
+        CSettingTrait() = delete;
+
+        //! Deleted copy constructor.
+        CSettingTrait(const CSettingTrait &) = delete;
+
+        //! Deleted copy assignment operator.
+        CSettingTrait &operator =(const CSettingTrait &) = delete;
+    };
+}
+
+#endif