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/*
* Copyright © 2021 Michael Smith <mikesmiffy128@gmail.com>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
#ifndef INC_VCALL_H
#define INC_VCALL_H
/*
* Convenient facilities for calling simple (single-table) virtual functions on
* possibly-opaque pointers to C++ objects.
*/
#ifdef _WIN32
#if defined(__GNUC__) || defined(__clang__)
#define VCALLCONV __thiscall
#else
// XXX: could support MSVC via __fastcall and dummy param, but is there a point?
#error C __thiscall support requires Clang or GCC
#endif
#else
#define VCALLCONV
#endif
#define DECL_VFUNC0(ret, name, idx) \
enum { _VTIDX_##name = (idx) }; \
typedef ret (*VCALLCONV _VFUNC_##name)(void *this);
#define DECL_VFUNC(ret, name, idx, ...) \
enum { _VTIDX_##name = (idx) }; \
typedef ret (*VCALLCONV _VFUNC_##name)(void *this, __VA_ARGS__);
// not bothering to provide a zero-argument version because the main use of
// this is vararg functions, which error if __thiscall
#define DECL_VFUNC_CDECL(ret, name, idx, ...) \
enum { _VTIDX_##name = (idx) }; \
typedef ret (*_VFUNC_##name)(void *this, __VA_ARGS__);
#define VFUNC(x, name) ((*(_VFUNC_##name **)(x))[_VTIDX_##name])
#define VCALL0(x, name) (VFUNC(x, name)(x))
#define VCALL(x, name, ...) VFUNC(x, name)(x, __VA_ARGS__)
#endif
// vi: sw=4 ts=4 noet tw=80 cc=80
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