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