62 lines
1.2 KiB
C++
62 lines
1.2 KiB
C++
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/*
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Copyright 2021 Glen Joseph Fernandes
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(glenjofe@gmail.com)
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Distributed under the Boost Software License, Version 1.0.
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(http://www.boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_FUNCTIONAL_IDENTITY_HPP
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#define BOOST_FUNCTIONAL_IDENTITY_HPP
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#include <boost/config.hpp>
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#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
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#include <utility>
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#endif
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namespace boost {
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struct identity {
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typedef void is_transparent;
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#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
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template<class T>
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BOOST_CONSTEXPR T&& operator()(T&& value) const BOOST_NOEXCEPT {
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return std::forward<T>(value);
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}
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#else
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template<class T>
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BOOST_CONSTEXPR const T& operator()(const T& value) const BOOST_NOEXCEPT {
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return value;
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}
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template<class T>
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BOOST_CONSTEXPR T& operator()(T& value) const BOOST_NOEXCEPT {
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return value;
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}
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#endif
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template<class>
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struct result { };
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template<class T>
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struct result<identity(T&)> {
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typedef T& type;
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};
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#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
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template<class T>
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struct result<identity(T)> {
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typedef T&& type;
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};
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template<class T>
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struct result<identity(T&&)> {
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typedef T&& type;
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};
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#endif
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};
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} // boost
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#endif
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