/
constify.h
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/
constify.h
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/*
* Copyright (c) 2016, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
#ifndef FATAL_INCLUDE_fatal_type_constify_h
#define FATAL_INCLUDE_fatal_type_constify_h
#include <fatal/type/add_reference_from.h>
#include <type_traits>
namespace fatal {
/**
* Adds the const qualifier to a type.
*
* If the type is a reference, to some other type `U`,
* make it the same kind of reference to `U const`.
*
* Example:
*
* // yields `int const`
* using result1 = constify<int>::type;
*
* // yields `int const &`
* using result2 = constify<int &>::type;
*
* // yields `int const &&`
* using result3 = constify<int &&>::type;
*
* // yields `int const &`
* using result4 = constify<int const &>::type;
*
* // yields `int *const`
* using result4 = constify<int *>::type;
*
* @author: Marcelo Juchem <marcelo@fb.com>
*/
template <typename T>
struct constify {
using type = typename add_reference_from<
typename std::decay<T>::type const,
T
>::type;
};
} // namespace fatal
#endif // FATAL_INCLUDE_fatal_type_constify_h