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NS/releases/3.05/source/common/interface.h

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// This header defines the interface convention used in the valve engine.
// To make an interface and expose it:
// 1. Derive from IBaseInterface.
// 2. The interface must be ALL pure virtuals, and have no data members.
// 3. Define a name for it.
// 4. In its implementation file, use EXPOSE_INTERFACE or EXPOSE_SINGLE_INTERFACE.
// Versioning
// There are two versioning cases that are handled by this:
// 1. You add functions to the end of an interface, so it is binary compatible with the previous interface. In this case,
// you need two EXPOSE_INTERFACEs: one to expose your class as the old interface and one to expose it as the new interface.
// 2. You update an interface so it's not compatible anymore (but you still want to be able to expose the old interface
// for legacy code). In this case, you need to make a new version name for your new interface, and make a wrapper interface and
// expose it for the old interface.
#ifndef INTERFACE_H
#define INTERFACE_H
#ifdef __cplusplus
// All interfaces derive from this.
class IBaseInterface
{
public:
virtual ~IBaseInterface() {}
};
#define CREATEINTERFACE_PROCNAME "CreateInterface"
typedef IBaseInterface* (*CreateInterfaceFn)(const char *pName, int *pReturnCode);
typedef IBaseInterface* (*InstantiateInterfaceFn)();
// Used internally to register classes.
class InterfaceReg
{
public:
InterfaceReg(InstantiateInterfaceFn fn, const char *pName);
public:
InstantiateInterfaceFn m_CreateFn;
const char *m_pName;
InterfaceReg *m_pNext; // For the global list.
static InterfaceReg *s_pInterfaceRegs;
};
// Use this to expose an interface that can have multiple instances.
// e.g.:
// EXPOSE_INTERFACE( CInterfaceImp, IInterface, "MyInterface001" )
// This will expose a class called CInterfaceImp that implements IInterface (a pure class)
// clients can receive a pointer to this class by calling CreateInterface( "MyInterface001" )
//
// In practice, the shared header file defines the interface (IInterface) and version name ("MyInterface001")
// so that each component can use these names/vtables to communicate
//
// A single class can support multiple interfaces through multiple inheritance
//
#define EXPOSE_INTERFACE_FN(functionName, interfaceName, versionName) \
static InterfaceReg __g_Create##className##_reg(functionName, versionName);
#define EXPOSE_INTERFACE(className, interfaceName, versionName) \
static IBaseInterface* __Create##className##_interface() {return (interfaceName *)new className;}\
static InterfaceReg __g_Create##className##_reg(__Create##className##_interface, versionName );
// Use this to expose a singleton interface with a global variable you've created.
#define EXPOSE_SINGLE_INTERFACE_GLOBALVAR(className, interfaceName, versionName, globalVarName) \
static IBaseInterface* __Create##className##interfaceName##_interface() {return (interfaceName *)&globalVarName;}\
static InterfaceReg __g_Create##className##interfaceName##_reg(__Create##className##interfaceName##_interface, versionName);
// Use this to expose a singleton interface. This creates the global variable for you automatically.
#define EXPOSE_SINGLE_INTERFACE(className, interfaceName, versionName) \
static className __g_##className##_singleton;\
EXPOSE_SINGLE_INTERFACE_GLOBALVAR(className, interfaceName, versionName, __g_##className##_singleton)
#ifdef WIN32
#define EXPORT_FUNCTION __declspec(dllexport)
#else
#define EXPORT_FUNCTION
#endif
// This function is automatically exported and allows you to access any interfaces exposed with the above macros.
// if pReturnCode is set, it will return one of the following values
// extend this for other error conditions/code
enum
{
IFACE_OK = 0,
IFACE_FAILED
};
extern "C"
{
EXPORT_FUNCTION IBaseInterface* CreateInterface(const char *pName, int *pReturnCode);
};
// Handle to an interface (HInterfaceModule_t* is just there for type safety).
typedef struct HInterfaceModule_t* HINTERFACEMODULE;
// Use these to load and unload a module.
extern HINTERFACEMODULE Sys_LoadModule(const char *pModuleName);
extern void Sys_FreeModule(HINTERFACEMODULE hModule);
// Use these to get the factory function from either a loaded module or the current module.
extern CreateInterfaceFn Sys_GetFactory( HINTERFACEMODULE hModule );
extern CreateInterfaceFn Sys_GetFactoryThis( void );
#endif // __cplusplus
#endif