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