ExtensionRegistration.hpp

//
//  ExtensionRegistration.hpp
//  SwitchboardSDK
//
 
#pragma once
 
// This header is intentionally free of any other switchboard_core includes beyond what the
// macro's expansion needs to compile; extensions already include ExtensionManager.hpp (or a
// header that does) wherever they define their `load()` method.
 
#if defined(_WIN32)
#define SWITCHBOARD_EXTENSION_ANCHOR_EXPORT __declspec(dllexport)
#else
#define SWITCHBOARD_EXTENSION_ANCHOR_EXPORT
#endif
 
#define SWITCHBOARD_EXTENSION_CONCAT_IMPL(a, b) a##b
#define SWITCHBOARD_EXTENSION_CONCAT(a, b) SWITCHBOARD_EXTENSION_CONCAT_IMPL(a, b)
 
// Defined by switchboard_add_extension() as a compile definition equal to the extension's own
// CMake target name (e.g. SwitchboardSileroVAD). Falls back to a placeholder so this header
// still compiles (with a non-unique anchor symbol) if included outside that build path.
#ifndef SWITCHBOARD_EXTENSION_TARGET_NAME
#define SWITCHBOARD_EXTENSION_TARGET_NAME UnknownSwitchboardExtension
#endif

#define SWITCHBOARD_REGISTER_EXTENSION(ClassName) \
    namespace { \
    struct SWITCHBOARD_EXTENSION_CONCAT(ClassName, AutoRegistrar) { \
        SWITCHBOARD_EXTENSION_CONCAT(ClassName, AutoRegistrar)() { \
            ClassName::load(); \
        } \
    }; \
    static const SWITCHBOARD_EXTENSION_CONCAT(ClassName, AutoRegistrar) SWITCHBOARD_EXTENSION_CONCAT( \
        ClassName, \
        AutoRegistrarInstance \
    ); \
    } \
    SWITCHBOARD_REGISTER_EXTENSION_PLATFORM_HOOKS()
 
#if !defined(SWITCHBOARD_WEB)
// `sb_extension_load` is kept exported (now an intentional no-op — the registrar above already
// ran registration) purely so ExtensionLoader::loadExtensionLibrary's dlopen/dlsym contract, and
// its "is this a valid Switchboard extension" check, keep working unmodified for extensions that
// are dlopen'd at runtime instead of linked at build time.
//
// `sb_extension_anchor_<TargetName>` exists only to be referenced by switchboard_link_extensions()
// via MSVC's `/INCLUDE` linker switch, forcing this extension's DLL into the consumer's import
// table on Windows even though nothing in the consumer's C++ source calls anything from it.
#define SWITCHBOARD_REGISTER_EXTENSION_PLATFORM_HOOKS() \
    extern "C" void sb_extension_load() {} \
    extern "C" SWITCHBOARD_EXTENSION_ANCHOR_EXPORT void \
        SWITCHBOARD_EXTENSION_CONCAT(sb_extension_anchor_, SWITCHBOARD_EXTENSION_TARGET_NAME)() {}
#else
#define SWITCHBOARD_REGISTER_EXTENSION_PLATFORM_HOOKS()
#endif