NOISSUE reorganize and document libraries

api/logic/resources/Resource.cpp

@@ -0,0 +1,155 @@
+#include "Resource.h"
+
+#include <QDebug>
+
+#include "ResourceObserver.h"
+#include "ResourceHandler.h"
+
+// definition of static members of Resource
+QMap<QString, std::function<std::shared_ptr<ResourceHandler>(const QString &)>> Resource::m_handlers;
+QMap<QPair<int, int>, std::function<QVariant(QVariant)>> Resource::m_transfomers;
+QMap<QString, std::weak_ptr<Resource>> Resource::m_resources;
+
+struct NullResourceResult {};
+Q_DECLARE_METATYPE(NullResourceResult)
+class NullResourceHandler : public ResourceHandler
+{
+public:
+	explicit NullResourceHandler()
+	{
+		setResult(QVariant::fromValue<NullResourceResult>(NullResourceResult()));
+	}
+};
+
+Resource::Resource(const QString &resource)
+	: m_resource(resource)
+{
+	if (!resource.isEmpty())
+	{
+		// a valid resource identifier has the format <id>:<data>
+		Q_ASSERT(resource.contains(':'));
+		// "parse" the resource identifier into id and data
+		const QString resourceId = resource.left(resource.indexOf(':'));
+		const QString resourceData = resource.mid(resource.indexOf(':') + 1);
+
+		// create and set up the handler
+		Q_ASSERT(m_handlers.contains(resourceId));
+		m_handler = m_handlers.value(resourceId)(resourceData);
+	}
+	else
+	{
+		m_handler = std::make_shared<NullResourceHandler>();
+	}
+
+	Q_ASSERT(m_handler);
+	m_handler->init(m_handler);
+	m_handler->setResource(this);
+}
+Resource::~Resource()
+{
+	qDeleteAll(m_observers);
+}
+
+Resource::Ptr Resource::create(const QString &resource, Ptr placeholder)
+{
+	const QString storageId = storageIdentifier(resource, placeholder);
+
+	// do we already have a resource? even if m_resources contains it it might not be valid any longer (weak_ptr)
+	Resource::Ptr ptr = m_resources.contains(storageId)
+			? m_resources.value(storageId).lock()
+			: nullptr;
+	// did we have one? and is it still valid?
+	if (!ptr)
+	{
+		/* We don't want Resource to have a public constructor, but std::make_shared needs it,
+		 * so we create a subclass of Resource here that exposes the constructor as public.
+		 * The alternative would be making the allocator for std::make_shared a friend, but it
+		 * differs between different STL implementations, so that would be a pain.
+		 */
+		struct ConstructableResource : public Resource
+		{
+			explicit ConstructableResource(const QString &resource)
+				: Resource(resource) {}
+		};
+		ptr = std::make_shared<ConstructableResource>(resource);
+		ptr->m_placeholder = placeholder;
+		m_resources.insert(storageId, ptr);
+	}
+	return ptr;
+}
+
+Resource::Ptr Resource::applyTo(ResourceObserver *observer)
+{
+	m_observers.append(observer);
+	observer->setSource(shared_from_this()); // give the observer a shared_ptr for us so we don't get deleted
+	observer->resourceUpdated(); // ask the observer to poll us immediently, we might already have data
+	return shared_from_this(); // allow chaining
+}
+Resource::Ptr Resource::applyTo(QObject *target, const char *property)
+{
+	// the cast to ResourceObserver* is required to ensure the right overload gets choosen,
+	// since QObjectResourceObserver also inherits from QObject
+	return applyTo(static_cast<ResourceObserver *>(new QObjectResourceObserver(target, property)));
+}
+
+QVariant Resource::getResourceInternal(const int typeId) const
+{
+	// no result (yet), but a placeholder? delegate to the placeholder.
+	if (m_handler->result().isNull() && m_placeholder)
+	{
+		return m_placeholder->getResourceInternal(typeId);
+	}
+	const QVariant variant = m_handler->result();
+	const auto typePair = qMakePair(int(variant.type()), typeId);
+
+	// do we have an explicit transformer? use it.
+	if (m_transfomers.contains(typePair))
+	{
+		return m_transfomers.value(typePair)(variant);
+	}
+	else
+	{
+		// we do not have an explicit transformer, so we just pass the QVariant, which will automatically
+		// transform some types for us (different numbers to each other etc.)
+		return variant;
+	}
+}
+
+void Resource::reportResult()
+{
+	for (ResourceObserver *observer : m_observers)
+	{
+		observer->resourceUpdated();
+	}
+}
+void Resource::reportFailure(const QString &reason)
+{
+	for (ResourceObserver *observer : m_observers)
+	{
+		observer->setFailure(reason);
+	}
+}
+void Resource::reportProgress(const int progress)
+{
+	for (ResourceObserver *observer : m_observers)
+	{
+		observer->setProgress(progress);
+	}
+}
+
+void Resource::notifyObserverDeleted(ResourceObserver *observer)
+{
+	m_observers.removeAll(observer);
+}
+
+QString Resource::storageIdentifier(const QString &id, Resource::Ptr placeholder)
+{
+	if (placeholder)
+	{
+		return id + '#' + storageIdentifier(placeholder->m_resource, placeholder->m_placeholder);
+	}
+	else
+	{
+		return id;
+	}
+}