Initial release

engine/vendor/vst3sdk/vstgui4/vstgui/lib/idependency.h

@@ -0,0 +1,119 @@
+// This file is part of VSTGUI. It is subject to the license terms 
+// in the LICENSE file found in the top-level directory of this
+// distribution and at http://github.com/steinbergmedia/vstgui/LICENSE
+
+#pragma once
+
+#include "vstguibase.h"
+
+#if VSTGUI_ENABLE_DEPRECATED_METHODS
+
+#include "vstguidebug.h"
+#include <list>
+#include <set>
+#include <algorithm>
+#include <cassert>
+
+namespace VSTGUI {
+
+//----------------------------------------------------------------------------------------------------
+/** @brief simple dependency between objects.
+	@ingroup new_in_4_0
+
+	@details You can inject this implementation into CBaseObjects whenever you need other CBaseObjects to be informed about
+	changes to that class instance. Note that you need to handle recursions yourself and that no reference counting is done
+	and that you must make sure that the dependent objects are alife while added as dependent.
+*/
+//----------------------------------------------------------------------------------------------------
+class [[deprecated("Please use listeners instead")]] IDependency
+{
+public:
+	/** add a dependent object */
+	virtual void addDependency (CBaseObject* obj);
+	/** remove a dependent object. */
+	virtual void removeDependency (CBaseObject* obj);
+	/** notify dependent objects of change with message. */
+	virtual void changed (IdStringPtr message);
+	/** defer changes until later. can be nested. If you use this, you must make sure that all message pointers are valid the whole time. */
+	virtual void deferChanges (bool state);
+
+	/** helper class to defer changes until instance is destroyed. */
+	class DeferChanges
+	{
+	public:
+		explicit DeferChanges (IDependency* dep) : dep (dep) { dep->deferChanges (true); }
+		~DeferChanges () noexcept { dep->deferChanges (false); }
+	protected:
+		IDependency* dep;
+	};
+
+//----------------------------------------------------------------------------------------------------
+protected:
+	IDependency () = default;
+	virtual ~IDependency () noexcept;
+
+	static void rememberObject (CBaseObject* obj) { obj->remember (); }
+	static void forgetObject (CBaseObject* obj) { obj->forget (); }
+
+	using DeferedChangesSet = std::set<IdStringPtr>;
+	using DependentList = std::list<CBaseObject*>;
+
+	int32_t deferChangeCount {0};
+	DeferedChangesSet deferedChanges;
+	DependentList dependents;
+};
+
+//----------------------------------------------------------------------------------------------------
+inline void IDependency::addDependency (CBaseObject* obj)
+{
+	dependents.emplace_back (obj);
+}
+
+//----------------------------------------------------------------------------------------------------
+inline void IDependency::removeDependency (CBaseObject* obj)
+{
+	dependents.remove (obj);
+}
+
+//----------------------------------------------------------------------------------------------------
+inline void IDependency::changed (IdStringPtr message)
+{
+	if (deferChangeCount)
+	{
+		deferedChanges.emplace (message);
+	}
+	else if (dependents.empty () == false)
+	{
+		auto* This = dynamic_cast<CBaseObject*> (this);
+		DependentList localList (dependents);
+		std::for_each (localList.begin (), localList.end (), rememberObject);
+		for (auto& obj : localList)
+			obj->notify (This, message);
+		std::for_each (localList.begin (), localList.end (), forgetObject);
+	}
+}
+
+//----------------------------------------------------------------------------------------------------
+inline void IDependency::deferChanges (bool state)
+{
+	if (state)
+	{
+		deferChangeCount++;
+	}
+	else if (--deferChangeCount == 0)
+	{
+		for (auto& msg : deferedChanges)
+			changed (msg);
+		deferedChanges.clear ();
+	}
+}
+
+//----------------------------------------------------------------------------------------------------
+inline IDependency::~IDependency () noexcept
+{
+	vstgui_assert (dependents.empty ());
+}
+
+} // VSTGUI
+
+#endif // VSTGUI_ENABLE_DEPRECATED_METHODS