Edit: /usr/include/boost/hof/identity.hpp (1884B)
/*=============================================================================
Copyright (c) 2012 Paul Fultz II
identity.h
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
==============================================================================*/
#ifndef BOOST_HOF_GUARD_FUNCTION_IDENTITY_H
#define BOOST_HOF_GUARD_FUNCTION_IDENTITY_H
/// identity
/// ========
///
/// Description
/// -----------
///
/// The `identity` function is an unary function object that returns whats given to it.
///
/// Semantics
/// ---------
///
/// assert(identity(x) == x);
///
/// Synopsis
/// --------
///
/// template
/// constexpr T identity(T&& x);
///
#include
#include
#include
#include
namespace boost { namespace hof { namespace identity_detail {
struct identity_base
{
template
constexpr T operator()(T&& x) const
noexcept(std::is_reference::value || BOOST_HOF_IS_NOTHROW_MOVE_CONSTRUCTIBLE(T))
{
return BOOST_HOF_FORWARD(T)(x);
}
template
constexpr std::initializer_list& operator()(std::initializer_list& x) const noexcept
{
return x;
}
template
constexpr const std::initializer_list& operator()(const std::initializer_list& x) const noexcept
{
return x;
}
template
constexpr std::initializer_list operator()(std::initializer_list&& x) const noexcept(noexcept(std::initializer_list(std::move(x))))
{
return BOOST_HOF_FORWARD(std::initializer_list)(x);
}
};
}
BOOST_HOF_DECLARE_STATIC_VAR(identity, identity_detail::identity_base);
}} // namespace boost::hof
#endif