XrDispatchTable.h

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// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.
 
#pragma once
 
#include <XrUtility/XrPlatformDependencies.h>
#include <openxr/openxr.h>
#include <openxr/openxr_platform.h>
#include <openxr/openxr_reflection.h>
 
#include "XrListFunctions.h"
 
 
namespace xr {
 
    struct DispatchTable {
#define XR_DISPATCH_TABLE_MEMBER(name) PFN_##name name{nullptr};
#define XR_DISPATCH_TABLE_MEMBER_VOID(name) PFN_xrVoidFunction name{nullptr};
 
        XR_LIST_FUNCTIONS_OPENXR_FUNCTIONS(XR_DISPATCH_TABLE_MEMBER);
        XR_LIST_FUNCTIONS_OPENXR_EXTENSIONS(XR_DISPATCH_TABLE_MEMBER, XR_DISPATCH_TABLE_MEMBER_VOID);
#undef XR_DISPATCH_TABLE_DEFINE_MEMBER
#undef XR_DISPATCH_TABLE_MEMBER_VOID
 
        void Initialize(XrInstance instance, PFN_xrGetInstanceProcAddr getInstanceProcAddr) {
            auto getFunctionPointer = [&](const char* name) -> PFN_xrVoidFunction {
                PFN_xrVoidFunction function = nullptr;
                (void)getInstanceProcAddr(instance, name, &function);
                return function;
            };
 
#define XR_DISPATCH_TABLE_GET_PROC_ADDRESS(name) name = reinterpret_cast<PFN_##name>(getFunctionPointer(#name));
#define XR_DISPATCH_TABLE_SET_NO_OP(name)
 
            XR_LIST_FUNCTIONS_OPENXR_FUNCTIONS(XR_DISPATCH_TABLE_GET_PROC_ADDRESS);
            XR_LIST_FUNCTIONS_OPENXR_EXTENSIONS(XR_DISPATCH_TABLE_GET_PROC_ADDRESS, XR_DISPATCH_TABLE_SET_NO_OP);
#undef XR_DISPATCH_TABLE_GET_PROC_ADDRESS
#undef XR_DISPATCH_TABLE_SET_NO_OP
        }
    };
} // namespace xr
 
// Add all xrFunctions, including extension functions, to the global namespace so they can be used as C functions.
#ifdef ENABLE_GLOBAL_XR_DISPATCH_TABLE
// clang-format off
    namespace xr {
        inline DispatchTable g_dispatchTable{};
    }
 
    #define XR_DISPATCH_TABLE_GLOBAL(name) inline const PFN_##name& name = xr::g_dispatchTable. name;
    #define XR_DISPATCH_TABLE_NO_OP(name)
 
    #if !defined(XR_NO_PROTOTYPES)
        // If openxr.h already defined function prototypes
        // avoid adding duplicated PFN aliases in global namespace
    #else
        XR_LIST_FUNCTIONS_OPENXR_FUNCTIONS(XR_DISPATCH_TABLE_GLOBAL);
    #endif
 
    #if !defined(XR_NO_PROTOTYPES) && defined(XR_EXTENSION_PROTOTYPES)
        // If openxr.h already defined extension function prototypes
        // avoid adding duplicated PFN aliases in global namespace
    #else
        XR_LIST_FUNCTIONS_OPENXR_EXTENSIONS(XR_DISPATCH_TABLE_GLOBAL, XR_DISPATCH_TABLE_NO_OP);
    #endif
 
    #undef XR_DISPATCH_TABLE_GLOBAL
    #undef XR_DISPATCH_TABLE_NO_OP
// clang-format on
#endif // ENABLE_GLOBAL_XR_DISPATCH_TABLE