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// Copyright (c) Meta Platforms, Inc. and affiliates.
// SPDX-License-Identifier: LGPL-2.1-or-later
/**
* @file
*
* Helpers for generic programming.
*/
#ifndef DRGN_GENERICS_H
#define DRGN_GENERICS_H
/**
* Choose a type based on a condition.
*
* @param[in] condition Controlling integer constant expression.
* @param[in] if_true Type if @p condition is non-zero.
* @param[in] if_false Type if @p condition is zero.
*/
#define type_if(condition, if_true, if_false) \
__typeof__( \
/* + 1 avoids a non-standard zero-length array. */ \
*_Generic((int (*)[!(condition) + 1])0, \
int (*)[1]: (__typeof__(if_true) *)0, \
int (*)[2]: (__typeof__(if_false) *)0) \
)
/**
* Define a typedef based on a condition.
*
* @param[in] name Name of type.
* @param[in] condition Controlling integer constant expression.
* @param[in] if_true Type if @p condition is non-zero.
* @param[in] if_false Type if @p condition is zero.
*/
#define typedef_if(name, condition, if_true, if_false) \
typedef type_if(condition, if_true, if_false) name
#endif /* DRGN_GENERICS_H */
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