1

public/appframework/IAppSystem.h

@@ -0,0 +1,122 @@
+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: An application framework 
+//
+// $Revision: $
+// $NoKeywords: $
+//=============================================================================//
+
+#ifndef IAPPSYSTEM_H
+#define IAPPSYSTEM_H
+
+#ifdef _WIN32
+#pragma once
+#endif
+
+#include "tier1/interface.h"
+
+
+//-----------------------------------------------------------------------------
+// Client systems are singleton objects in the client codebase responsible for
+// various tasks
+// The order in which the client systems appear in this list are the
+// order in which they are initialized and updated. They are shut down in
+// reverse order from which they are initialized.
+//-----------------------------------------------------------------------------
+
+enum InitReturnVal_t
+{
+	INIT_FAILED = 0,
+	INIT_OK,
+
+	INIT_LAST_VAL,
+};
+
+
+abstract_class IAppSystem
+{
+public:
+	// Here's where the app systems get to learn about each other 
+	virtual bool Connect( CreateInterfaceFn factory ) = 0;
+	virtual void Disconnect() = 0;
+
+	// Here's where systems can access other interfaces implemented by this object
+	// Returns NULL if it doesn't implement the requested interface
+	virtual void *QueryInterface( const char *pInterfaceName ) = 0;
+
+	// Init, shutdown
+	virtual InitReturnVal_t Init() = 0;
+	virtual void Shutdown() = 0;
+};
+
+
+//-----------------------------------------------------------------------------
+// Helper empty implementation of an IAppSystem
+//-----------------------------------------------------------------------------
+template< class IInterface > 
+class CBaseAppSystem : public IInterface
+{
+public:
+	// Here's where the app systems get to learn about each other 
+	virtual bool Connect( CreateInterfaceFn factory ) { return true; }
+	virtual void Disconnect() {}
+
+	// Here's where systems can access other interfaces implemented by this object
+	// Returns NULL if it doesn't implement the requested interface
+	virtual void *QueryInterface( const char *pInterfaceName ) { return NULL; }
+
+	// Init, shutdown
+	virtual InitReturnVal_t Init() { return INIT_OK; }
+	virtual void Shutdown() {}
+};
+
+
+//-----------------------------------------------------------------------------
+// Helper implementation of an IAppSystem for tier0
+//-----------------------------------------------------------------------------
+template< class IInterface > 
+class CTier0AppSystem : public CBaseAppSystem< IInterface >
+{
+public:
+	CTier0AppSystem( bool bIsPrimaryAppSystem = true )
+	{
+		m_bIsPrimaryAppSystem = bIsPrimaryAppSystem;
+	}
+
+protected:
+	// NOTE: a single DLL may have multiple AppSystems it's trying to
+	// expose. If this is true, you must return true from only
+	// one of those AppSystems; not doing so will cause all static
+	// libraries connected to it to connect/disconnect multiple times
+
+	// NOTE: We don't do this as a virtual function to avoid
+	// having to up the version on all interfaces
+	bool IsPrimaryAppSystem() { return m_bIsPrimaryAppSystem; }
+
+private:
+	bool m_bIsPrimaryAppSystem;
+};
+
+
+//-----------------------------------------------------------------------------
+// This is the version of IAppSystem shipped 10/15/04
+// NOTE: Never change this!!!
+//-----------------------------------------------------------------------------
+abstract_class IAppSystemV0
+{
+public:
+	// Here's where the app systems get to learn about each other 
+	virtual bool Connect( CreateInterfaceFn factory ) = 0;
+	virtual void Disconnect() = 0;
+
+	// Here's where systems can access other interfaces implemented by this object
+	// Returns NULL if it doesn't implement the requested interface
+	virtual void *QueryInterface( const char *pInterfaceName ) = 0;
+
+	// Init, shutdown
+	virtual InitReturnVal_t Init() = 0;
+	virtual void Shutdown() = 0;
+};
+
+#endif // IAPPSYSTEM_H
+