231 lines
9.0 KiB
C++
231 lines
9.0 KiB
C++
//========= Copyright Valve Corporation, All rights reserved. ============//
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//
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// Purpose:
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//
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// $NoKeywords: $
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//
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//=============================================================================//
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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. The interface must be ALL pure virtuals, and have no data members.
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// 2. Define a name for it.
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// 3. 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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// Static Linking:
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// Must mimic unique seperate class 'InterfaceReg' constructors per subsystem.
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// Each subsystem can then import and export interfaces as expected.
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// This is achieved through unique namespacing 'InterfaceReg' via symbol _SUBSYSTEM.
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// Static Linking also needs to generate unique symbols per interface so as to
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// provide a 'stitching' method whereby these interface symbols can be referenced
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// via the lib's primary module (usually the lib's interface exposure)
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// therby stitching all of that lib's code/data together for eventual final exe link inclusion.
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#ifndef INTERFACE_H
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#define INTERFACE_H
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#ifdef _WIN32
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#pragma once
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#endif
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#ifdef _LINUX
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#include <dlfcn.h> // dlopen,dlclose, et al
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#include <unistd.h>
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#define GetProcAddress dlsym
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#ifdef _snprintf
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#undef _snprintf
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#endif
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#define _snprintf snprintf
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#endif
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// TODO: move interface.cpp into tier0 library.
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#include "tier0/platform.h"
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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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#if !defined( _X360 )
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#define CREATEINTERFACE_PROCNAME "CreateInterface"
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#else
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// x360 only allows ordinal exports, .def files export "CreateInterface" at 1
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#define CREATEINTERFACE_PROCNAME ((const char*)1)
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#endif
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typedef void* (*CreateInterfaceFn)(const char *pName, int *pReturnCode);
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typedef void* (*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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// Use this if you want to write the factory function.
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#if !defined(_STATIC_LINKED) || !defined(_SUBSYSTEM)
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#define EXPOSE_INTERFACE_FN(functionName, interfaceName, versionName) \
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static InterfaceReg __g_Create##interfaceName##_reg(functionName, versionName);
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#else
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#define EXPOSE_INTERFACE_FN(functionName, interfaceName, versionName) \
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namespace _SUBSYSTEM \
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{ \
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static InterfaceReg __g_Create##interfaceName##_reg(functionName, versionName); \
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}
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#endif
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#if !defined(_STATIC_LINKED) || !defined(_SUBSYSTEM)
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#define EXPOSE_INTERFACE(className, interfaceName, versionName) \
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static void* __Create##className##_interface() {return static_cast<interfaceName *>( new className );} \
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static InterfaceReg __g_Create##className##_reg(__Create##className##_interface, versionName );
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#else
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#define EXPOSE_INTERFACE(className, interfaceName, versionName) \
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namespace _SUBSYSTEM \
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{ \
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static void* __Create##className##_interface() {return static_cast<interfaceName *>( new className );} \
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static InterfaceReg __g_Create##className##_reg(__Create##className##_interface, versionName ); \
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}
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#endif
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// Use this to expose a singleton interface with a global variable you've created.
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#if !defined(_STATIC_LINKED) || !defined(_SUBSYSTEM)
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#define EXPOSE_SINGLE_INTERFACE_GLOBALVAR_WITH_NAMESPACE(className, interfaceNamespace, interfaceName, versionName, globalVarName) \
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static void* __Create##className##interfaceName##_interface() {return static_cast<interfaceNamespace interfaceName *>( &globalVarName );} \
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static InterfaceReg __g_Create##className##interfaceName##_reg(__Create##className##interfaceName##_interface, versionName);
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#else
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#define EXPOSE_SINGLE_INTERFACE_GLOBALVAR_WITH_NAMESPACE(className, interfaceNamespace, interfaceName, versionName, globalVarName) \
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namespace _SUBSYSTEM \
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{ \
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static void* __Create##className##interfaceName##_interface() {return static_cast<interfaceNamespace interfaceName *>( &globalVarName );} \
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static InterfaceReg __g_Create##className##interfaceName##_reg(__Create##className##interfaceName##_interface, versionName); \
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}
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#endif
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#define EXPOSE_SINGLE_INTERFACE_GLOBALVAR(className, interfaceName, versionName, globalVarName) \
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EXPOSE_SINGLE_INTERFACE_GLOBALVAR_WITH_NAMESPACE(className, , interfaceName, versionName, globalVarName)
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// Use this to expose a singleton interface. This creates the global variable for you automatically.
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#if !defined(_STATIC_LINKED) || !defined(_SUBSYSTEM)
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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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#else
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#define EXPOSE_SINGLE_INTERFACE(className, interfaceName, versionName) \
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namespace _SUBSYSTEM \
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{ \
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static className __g_##className##_singleton; \
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} \
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EXPOSE_SINGLE_INTERFACE_GLOBALVAR(className, interfaceName, versionName, __g_##className##_singleton)
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#endif
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// load/unload components
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class CSysModule;
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// interface return status
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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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//-----------------------------------------------------------------------------
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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 (IFACE_OK, IFACE_FAILED)
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// extend this for other error conditions/code
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//-----------------------------------------------------------------------------
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DLL_EXPORT void* CreateInterface(const char *pName, int *pReturnCode);
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#if defined( _X360 )
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DLL_EXPORT void *CreateInterfaceThunk( const char *pName, int *pReturnCode );
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#endif
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//-----------------------------------------------------------------------------
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// UNDONE: This is obsolete, use the module load/unload/get instead!!!
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//-----------------------------------------------------------------------------
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extern CreateInterfaceFn Sys_GetFactory( CSysModule *pModule );
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extern CreateInterfaceFn Sys_GetFactory( const char *pModuleName );
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extern CreateInterfaceFn Sys_GetFactoryThis( void );
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enum Sys_Flags
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{
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SYS_NOFLAGS = 0x00,
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SYS_NOLOAD = 0x01 // no loading, no ref-counting, only returns handle if lib is loaded.
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};
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//-----------------------------------------------------------------------------
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// Load & Unload should be called in exactly one place for each module
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// The factory for that module should be passed on to dependent components for
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// proper versioning.
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//-----------------------------------------------------------------------------
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extern CSysModule *Sys_LoadModule( const char *pModuleName, Sys_Flags flags = SYS_NOFLAGS );
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extern void Sys_UnloadModule( CSysModule *pModule );
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// This is a helper function to load a module, get its factory, and get a specific interface.
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// You are expected to free all of these things.
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// Returns false and cleans up if any of the steps fail.
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bool Sys_LoadInterface(
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const char *pModuleName,
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const char *pInterfaceVersionName,
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CSysModule **pOutModule,
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void **pOutInterface );
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bool Sys_IsDebuggerPresent();
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//-----------------------------------------------------------------------------
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// Purpose: Place this as a singleton at module scope (e.g.) and use it to get the factory from the specified module name.
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//
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// When the singleton goes out of scope (.dll unload if at module scope),
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// then it'll call Sys_UnloadModule on the module so that the refcount is decremented
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// and the .dll actually can unload from memory.
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//-----------------------------------------------------------------------------
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class CDllDemandLoader
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{
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public:
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CDllDemandLoader( char const *pchModuleName );
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virtual ~CDllDemandLoader();
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CreateInterfaceFn GetFactory();
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void Unload();
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private:
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char const *m_pchModuleName;
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CSysModule *m_hModule;
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bool m_bLoadAttempted;
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};
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#endif
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