1 files changed, 73 insertions, 0 deletions
diff --git a/libraries/logic/resources/ResourceObserver.h b/libraries/logic/resources/ResourceObserver.h
new file mode 100644
index 00000000..c42e41ba
--- /dev/null
+++ b/libraries/logic/resources/ResourceObserver.h
@@ -0,0 +1,73 @@
+#pragma once
+
+#include <memory>
+#include <functional>
+
+#include <QObject>
+#include <QMetaProperty>
+#include "multimc_logic_export.h"
+
+class QVariant;
+class Resource;
+
+/// Base class for things that can use a resource
+class MULTIMC_LOGIC_EXPORT ResourceObserver
+{
+public:
+	virtual ~ResourceObserver();
+
+protected: // these methods are called by the Resource when something changes
+	virtual void resourceUpdated() = 0;
+	virtual void setFailure(const QString &) {}
+	virtual void setProgress(const int) {}
+
+private:
+	friend class Resource;
+	void setSource(std::shared_ptr<Resource> resource) { m_resource = resource; }
+
+protected:
+	template<typename T>
+	T get() const { return getInternal(qMetaTypeId<T>()).template value<T>(); }
+	QVariant getInternal(const int typeId) const;
+
+private:
+	std::shared_ptr<Resource> m_resource;
+};
+
+/** Observer for QObject properties
+ *
+ * Give it a target and the name of a property, and that property will be set when the resource changes.
+ *
+ * If no name is given an attempt to find a default property for some common classes is done.
+ */
+class MULTIMC_LOGIC_EXPORT QObjectResourceObserver : public QObject, public ResourceObserver
+{
+public:
+	explicit QObjectResourceObserver(QObject *target, const char *property = nullptr);
+
+	void resourceUpdated() override;
+
+private:
+	QObject *m_target;
+	QMetaProperty m_property;
+};
+
+/** Observer for functions, lambdas etc.
+ * Template arguments:
+ *   * We need Ret and Arg in order to create the std::function
+ *   * We need Func in order to std::forward the function
+ */
+template <typename Ret, typename Arg, typename Func>
+class FunctionResourceObserver : public ResourceObserver
+{
+	std::function<Ret(Arg)> m_function;
+public:
+	template <typename T>
+	explicit FunctionResourceObserver(T &&func)
+		: m_function(std::forward<Func>(func)) {}
+
+	void resourceUpdated() override
+	{
+		m_function(get<Arg>());
+	}
+};