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/*
* Copyright © 2022 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
#include "gamedata.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_VFUNC_DYN(ret, conv, name, ...) \
/* XXX: GCC extension, seems worthwhile vs having two macros for one thing.
Replace with __VA_OPT__(,) whenever that gets fully standardised. */ \
typedef ret (*conv name##_func)(void *this, ##__VA_ARGS__);
#define _DECL_VFUNC(ret, conv, name, idx, ...) \
enum { vtidx_##name = (idx) }; \
_DECL_VFUNC_DYN(ret, conv, name, ##__VA_ARGS__)
/* Define a virtual function with a known index */
#define DECL_VFUNC(ret, name, idx, ...) \
_DECL_VFUNC(ret, VCALLCONV, name, idx, ##__VA_ARGS__)
/* Define a virtual function with a known index, without thiscall convention */
#define DECL_VFUNC_CDECL(ret, name, idx, ...) \
_DECL_VFUNC(ret, , name, idx, ##__VA_ARGS__)
/* Define a virtual function with an index defined elsewhere */
#define DECL_VFUNC_DYN(ret, name, ...) \
_DECL_VFUNC_DYN(ret, VCALLCONV, name, ##__VA_ARGS__)
/* Define a virtual function with an index defined elsewhere, without thiscall */
#define DECL_VFUNC_CDECLDYN(ret, name, ...) \
_DECL_VFUNC_DYN(ret, , name, ##__VA_ARGS__)
#define VFUNC(x, name) ((*(name##_func **)(x))[vtidx_##name])
#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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