/
constify_from.h
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/
constify_from.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_from_h
#define FATAL_INCLUDE_fatal_type_constify_from_h
#include <fatal/type/constify.h>
namespace fatal {
///////////////////
// constify_from //
///////////////////
/**
* Applies `constify` to a type iff some other type is const.
*
* Example:
*
* struct foo {};
*
* // yields `foo const`
* using result1 = constify_from<foo, int const>::type;
*
* // yields `foo const &`
* using result2 = constify_from<foo &, int const>::type;
*
* // yields `foo &&`
* using result3 = constify_from<foo &&, int>::type;
*
* // yields `foo const &`
* using result4 = constify_from<foo const &, int const>::type;
*
* // yields `foo const &`
* using result5 = constify_from<foo const &, int>::type;
*
* @author: Marcelo Juchem <marcelo@fb.com>
*/
template <typename T, typename>
struct constify_from {
using type = T;
};
template <typename T, typename TFrom>
struct constify_from<T, TFrom const> {
using type = typename constify<T>::type;
};
} // namespace fatal
#endif // FATAL_INCLUDE_fatal_type_constify_from_h