chromium/third_party/libc++/src/include/__functional/identity.h

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___FUNCTIONAL_IDENTITY_H
#define _LIBCPP___FUNCTIONAL_IDENTITY_H

#include <__config>
#include <__fwd/functional.h>
#include <__type_traits/integral_constant.h>
#include <__utility/forward.h>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

template <class _Tp>
struct __is_identity : false_type { … };

struct __identity { … };

template <>
struct __is_identity<__identity> : true_type { … };
template <>
struct __is_identity<reference_wrapper<__identity> > : true_type { … };
template <>
struct __is_identity<reference_wrapper<const __identity> > : true_type { … };

#if _LIBCPP_STD_VER >= 20

struct identity { … };

template <>
struct __is_identity<identity> : true_type { … };
template <>
struct __is_identity<reference_wrapper<identity> > : true_type { … };
template <>
struct __is_identity<reference_wrapper<const identity> > : true_type { … };

#endif // _LIBCPP_STD_VER >= 20

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___FUNCTIONAL_IDENTITY_H