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/* libmisc/private.h - Utilities to hide struct fields
*
* Copyright (C) 2024 Luke T. Shumaker <lukeshu@lukeshu.com>
* SPDX-License-Identifier: AGPL-3.0-or-later
*/
#ifndef _LIBMISC_CPPUTIL_H_
#define _LIBMISC_CPPUTIL_H_
/* primitive utilities */
#define _SECOND(a, b, ...) b
#define _CAT(a, b) a ## b
#define _CAT2(a, b) _CAT(a, b)
#define _EAT(...)
#define _EXPAND(...) __VA_ARGS__
/* conditionals */
#define _T xxTxx
#define _F xxFxx
#define _SENTINEL() bogus, _T /* a magic sentinel value */
#define _IS_SENTINEL(...) _SECOND(__VA_ARGS__, _F)
#define _IF(cond) _CAT(_IF__, cond) /* _IF(cond)(then)(else) */
#define _IF__xxTxx(...) __VA_ARGS__ _EAT
#define _IF__xxFxx(...) _EXPAND
/* high-level functionality */
#define YES _SENTINEL()
#define BEGIN_PRIVATE(name) _IF(_IS_SENTINEL(IMPLEMENTATION_FOR_##name))()(struct {)
#define END_PRIVATE(name) _IF(_IS_SENTINEL(IMPLEMENTATION_FOR_##name))()(} _CAT2(_HIDDEN_, __COUNTER__);)
#endif /* _LIBMISC_CPPUTIL_H_ */
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